the effects of acute sodium ingestion on food and water ......research project in my final...

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The Effects of Acute Sodium Ingestion on Food and Water Intakes, Subjective Appetite, Thirst and Glycemic

Response in Healthy Young Men

by

Maria Fernanda Nunez

A thesis submitted in conformity with the requirements for the degree of Masters of Science

Graduate Department of Nutritional Sciences University of Toronto

© Copyright by Maria Fernanda Nunez 2011

ii

The Effects of Acute Sodium Ingestion on Food and Water Intakes, Subjective Appetite, Thirst and Glycemic Response in

Healthy Young Men

Maria Fernanda Nunez

Masters of Science

Graduate Department of Nutritional Sciences

University of Toronto

2011

Abstract

High dietary sodium intake is hypothesized to increase food intake (FI), fluid intake and

glycemic response. Two short-term randomized repeated-measures studies measured the effects

of acute sodium intake on FI, water intake (WI), subjective appetite (SA), thirst, and blood

glucose (BG) in young men. Sodium additions were 740 and 1480 mg to a solid food (beans) in

Experiment 1; and 500, 1000, 1500 and 2000 mg to a beverage (tomato juice) in Experiment 2.

FI and WI were measured at ad libitum pizza meals 120 and 30 min later, respectively. SA, thirst

and BG were measured at intervals before and after pizza. Compared with controls, treatments

with added-sodium had no effect on dependent measures. In conclusion, acute intake of sodium

in a solid or liquid matrix does not increase subjective ratings of appetite or thirst, ad libitum

food or water intakes, or blood glucose in healthy young adults.

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ACKNOWLEDGMENTS

To say the least, my M.Sc. journey was colorful and often unpredictable. Many events occurred

related to my research and personal life that made this degree look almost impossible to finish.

However, Dr. Anderson, my family and friends (all my past and current lab mates included) gave

me the courage and determination I needed to see everything through.

Dr. Anderson, this degree would not have happened had it not been for you remarking “I can see

that you‟re enthusiastic about completing a fourth-year project” one sunny afternoon in

September 2008. I had tried without success to find a supervisor to complete an independent

research project in my final undergraduate year. After emailing you for advice on how I could go

about gaining research experience, we met and you brainstormed the first study of my thesis. I

have recounted this story many times (with more panache), particularly to our volunteers and

summer students, with the hope of conveying that it is a blessing to be taken under your wings.

Your tough-love style of mentoring was challenging at times but I know that without it, I would

not have achieved as much as I did. I cannot thank you enough, Dr. Anderson, for believing in

me when no one else did. Thank you, Dr. Greenwood and Dr. Mendelson, for your time and

advice during these three years and above all, your incredible support and positive energy during

my defence. Thank you, Dr. Darling for taking your time to be my external examiner and Dr.

Bazinet for being my chair. Finally, to Louisa, Emelia, Vijay and Lucille for always being so

kind to me and supportive!

To my lab mates: There are so many of you I need to thank including my incredible academic

and life mentors, Bohdan, Becky and Sandra; and my awesome friends, Michelle, Ati,

Shokoufeh, Shirin, Szeto, Tina, Pedro, Nick, Ali, Diana, Abby, Barkha, Christina, Ting Ting,

Abe, Chris, Clara, Shlomi, Svitlana and Nandini. To keep things short and sweet, I dedicate the

following sentences to everyone past and present. I never expressed how much your support has

meant to me, especially within the last year, for fear of sounding too sentimental. You helped me

see the light whenever things got too dark, gave me hope when I thought everything was lost,

and believed in me when I felt like a major flop. THANK YOU for your mentorship, kind words,

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patience, affection, and the hundreds of beautiful memories we shared that I will cherish forever.

Love you always.

Above all, thank you to my family. Querida mamá y abuelita, nada de esto hubiera sido posible

sin su amor, paciencia, fe en mí y fuerza. Cuantas veces dude en mi capacidad de cumplir este

paso en mi vida profesional pero nunca me dejaron caer en mis inseguridades. Me dieron apoyo

incondicional en medio de la oscuridad que pasamos estos últimos años y esto no tiene precio.

Ustedes son todo para mí; Dios sabe cuánto las quiero y que no sería ni un decimo de la mujer

que soy si no fuera por ustedes. Nos queda mucho más para recorrer juntas y que Dios me las

bendiga siempre.

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TABLE OF CONTENTS

Abstract ........................................................................................................................................... ii

Acknowledgments .......................................................................................................................... iii

Table of Contents ............................................................................................................................ v

List of Tables ............................................................................................................................... xiv

List of Figures .............................................................................................................................. xxi

List of Abbreviations .................................................................................................................. xxii

Chapter 1 INTRODUCTION .......................................................................................................... 1

1.1 Introduction ...................................................................................................................... 1

Chapter 2 LITERATURE REVIEW ............................................................................................... 3

2.1 Introduction ...................................................................................................................... 3

2.2 History of Sodium in the Human Diet ............................................................................. 3

2.3 Current and Recommended Sodium Intakes .................................................................... 4

2.4 Dietary Sodium Sources ................................................................................................... 5

2.5 Food Uses of Salt and Other Sodium Compounds ........................................................... 5

2.5.1 Sodium Chloride and Prevention of Food Spoilage ................................................. 5

2.5.2 Salt Taste Perception and Food Palatability ............................................................. 6

2.5.3 Additional Sodium Compounds and Associated Health Risks ................................. 7

vi

2.5.3.1 Sodium Nitrite ................................................................................................... 7

2.5.3.2 Monosodium Glutamate (MSG) ........................................................................ 8

2.6 Sodium: From Vital Nutrient to Health Risk Factor ........................................................ 8

2.7 Sodium, Increased Fluid Intake and Energy Balance .................................................... 10

2.7.1 Sodium, Intracellular Thirst and Fluid Regulation ................................................. 11

2.7.2 The Relationship between Fluid and Energy Intake ............................................... 14

2.8 Sodium and Energy Intake Regulation ........................................................................... 15

2.8.1 Obesity and Energy Balance Overview .................................................................. 16

2.8.2 Savoury Foods and Weight Status .......................................................................... 16

2.8.3 Sodium Absorption and Delayed Gastric Emptying ............................................... 17

2.8.4 Sodium, Subjective Appetite and Food Intake ....................................................... 18

2.9 Sodium Intake and Glycemic Control ............................................................................ 20

2.9.1 Carbohydrates and Sodium Absorption .................................................................. 21

2.9.2 Food Matrix Form, Sodium and Gastric Emptying ................................................ 21

2.9.3 Acute Sodium Ingestion and Glycaemia ................................................................. 22

2.9.4 Chronic Sodium Ingestion and Glycaemia ............................................................. 23

2.9.5 Insulin Resistance, Obesity and Sodium Balance Dysregulation ........................... 24

2.10 Summary ..................................................................................................................... 25

Chapter 3 RATIONALE, HYPOTHESIS AND OBJECTIVES .................................................. 26

3.1 Rationale ......................................................................................................................... 26

vii

3.2 Overall Hypothesis ......................................................................................................... 26

3.3 Overall Objective ........................................................................................................... 26

3.3.1 Specific Objectives ................................................................................................. 26

Chapter 4 MATERIALS AND METHODS ................................................................................. 27

4.1 Subjects .......................................................................................................................... 27

4.2 Study Design .................................................................................................................. 28

4.2.1 Experiment 1 Treatments ........................................................................................ 29

4.2.2 Experiment 2 Treatments ........................................................................................ 30

4.3 Experimental Protocol .................................................................................................... 33

4.3.1 Screening and Baseline ........................................................................................... 33

4.3.2 Experimental Protocol ............................................................................................ 34

4.4 Dependent Measures ...................................................................................................... 34

4.4.1 Visual Analogue Scale (VAS) Questionnaires ....................................................... 34

4.4.1.1 Subjective Appetite (SA) ................................................................................. 35

4.4.1.2 Subjective Thirst .............................................................................................. 35

4.4.1.3 Physical Comfort ............................................................................................. 35

4.4.1.4 Subjective Palatability ..................................................................................... 36

4.4.2 Blood Glucose Concentrations ............................................................................... 36

4.4.3 Test Meal ................................................................................................................ 37

4.5 Data Analysis ................................................................................................................. 37

viii

Chapter 5 RESULTS ..................................................................................................................... 40

5.1 Subject Characteristics ................................................................................................... 40

5.2 Treatment and Test Meal Palatability ............................................................................ 43

5.2.1 Treatment Palatability Ratings ................................................................................ 43

5.2.2 Test Meal Palatability Ratings ................................................................................ 43

5.3 Food, Sodium and Water Intakes ................................................................................... 45

5.3.1 Food Intake ............................................................................................................. 45

5.3.2 Sodium Intake ......................................................................................................... 45

5.3.3 Water Intake ............................................................................................................ 45

5.4 Subjective Average Appetite .......................................................................................... 47

5.4.1 Absolute Average Appetite Scores ......................................................................... 47

5.4.2 Change from Baseline Average Appetite Scores .................................................... 48

5.4.3 Average Appetite AUC ........................................................................................... 48

5.5 Subjective Thirst ............................................................................................................ 52

5.5.1 Absolute Thirst Ratings .......................................................................................... 52

5.5.2 Change from Baseline Thirst Ratings ..................................................................... 53

5.5.3 Thirst Net AUC ....................................................................................................... 53

5.6 Blood Glucose Response ................................................................................................ 57

5.6.1 Absolute Blood Glucose Concentrations ................................................................ 57

5.6.2 Change from Baseline Blood Glucose Concentrations ........................................... 57

ix

5.6.3 Blood Glucose Net AUC ........................................................................................ 58

5.7 Physical Comfort ............................................................................................................ 62

5.7.1 Absolute Average Physical Comfort Scores ........................................................... 62

5.7.2 Change from Baseline Average Physical Comfort Scores ..................................... 62

5.7.3 Average Physical Comfort net AUC ....................................................................... 62

Chapter 6 DISCUSSION, CONCLUSION AND FUTURE DIRECTIONS................................ 66

6.1 Discussion ...................................................................................................................... 66

6.2 Conclusion ...................................................................................................................... 72

6.3 Future Directions ............................................................................................................ 72

Chapter 7 REFERENCES ............................................................................................................. 74

Chapter 8 APPENDICES .............................................................................................................. 83

8.1 Appendix I: The Effects of Pre-meal Water Intake on Acute Food and Water Intakes

(Experiment 1b) ........................................................................................................................ 83

8.1.1 Background and Rationale ...................................................................................... 83

8.1.2 Hypothesis ............................................................................................................... 84

8.1.3 Objectives ............................................................................................................... 84

8.1.4 Materials and Methods ............................................................................................ 85

8.1.5 Statistical Analysis .................................................................................................. 85

8.1.6 Results ..................................................................................................................... 85

8.1.6.1 Treatment and Test Meal Palatability .............................................................. 86

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8.1.6.2 Food, Sodium and Water Intakes .................................................................... 86

8.1.6.3 Absolute Average Appetite Scores .................................................................. 86

8.1.6.4 Change from Baseline Average Appetite Scores............................................. 86

8.1.6.5 Average Appetite Net AUC ............................................................................. 87

8.1.6.6 Absolute Thirst Ratings ................................................................................... 87

8.1.6.7 Change from Baseline Thirst Ratings .............................................................. 87

8.1.6.8 Thirst Net AUC ............................................................................................... 87

8.1.6.9 Absolute Blood Glucose Concentrations ......................................................... 88

8.1.6.10 Change from Baseline Blood Glucose Concentrations ................................... 88

8.1.6.11 Blood Glucose Net AUC ................................................................................. 88

8.1.6.12 Absolute Average Physical Comfort Scores ................................................... 88

8.1.6.13 Change from Baseline Average Physical Comfort Scores .............................. 88

8.1.6.14 Average Physical Comfort Net AUC .............................................................. 88

8.1.7 Discussion ............................................................................................................... 89

8.1.8 Conclusion .............................................................................................................. 91

8.2 Appendix II: Supplementary Results for Experiment 1 ............................................... 102

8.2.1 Screening Food Frequency Questionnaire Data ................................................... 102

8.2.2 Past 24-hour Food Intake, Physical Activity and Stress Levels ........................... 102

8.2.3 Food, Sodium and Water Intakes with Covariates ................................................ 103

8.2.4 Desire to Eat .......................................................................................................... 104

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8.2.5 Hunger ................................................................................................................... 106

8.2.6 Fullness ................................................................................................................. 108

8.2.7 Prospective Food Consumption ............................................................................ 110

8.2.8 Nausea ................................................................................................................... 112

8.2.9 Stomach Pain ........................................................................................................ 114

8.2.10 Wellness ................................................................................................................ 116

8.2.11 Flatulence .............................................................................................................. 118

8.2.12 Diarrhoea ............................................................................................................... 120

8.3 Appendix III: Supplementary Results for Experiment 2 .............................................. 122

8.3.1 Screening Food Frequency Questionnaire Data ................................................... 122

8.3.2 Past 24-hour Food Intake, Physical Activity and Stress Levels ........................... 122

8.3.3 Food, Sodium and Water Intakes with Covariates ................................................ 123

8.3.4 Desire to Eat .......................................................................................................... 124

8.3.5 Hunger ................................................................................................................... 126

8.3.6 Fullness ................................................................................................................. 128

8.3.7 Prospective Food Consumption ............................................................................ 130

8.3.8 Nausea ................................................................................................................... 132

8.3.9 Stomach Pain ........................................................................................................ 134

8.3.10 Wellness ................................................................................................................ 136

8.3.11 Flatulence .............................................................................................................. 138

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8.3.12 Diarrhoea ............................................................................................................... 140

8.3.13 Correlations ........................................................................................................... 142

8.4 Appendix VI: Sample Size Calculations ..................................................................... 146

8.5 Appendix V: Treatment Randomization Order ............................................................ 147

8.5.1 Experiment 1 Randomization Table ..................................................................... 147

8.5.2 Experiment 2 Randomization Table ..................................................................... 147

8.6 Appendix VI: Experiment 2 Treatment Recipe ............................................................ 148

8.7 Appendix VII: Pizza Nutritional Composition............................................................. 149

8.8 Appendix VIII: Experiment 1 Consent Form ............................................................... 150

8.9 Appendix IX: Experiment 2 Consent Form ................................................................. 155

8.10 Appendix X: Screening Questionnaire ..................................................................... 161

8.10.1 Recruitment Screening Questionnaire .................................................................. 161

8.10.2 Sleep Habits Questionnaire ................................................................................... 162

8.10.3 Eating Habits Questionnaire ................................................................................. 163

8.10.4 Food Acceptability Questionnaire ........................................................................ 164

8.10.5 Recruitment Advertising ....................................................................................... 165

8.11 Appendix XI: Study Day Session Forms .................................................................. 166

8.11.1 Sleep Habits and Stress Questionnaire ................................................................. 166

8.11.2 Recent Food Intake and Activity Questionnaire ................................................... 167

8.11.3 Motivation to Eat VAS ......................................................................................... 168

xiii

8.11.4 Physical Comfort VAS ......................................................................................... 169

8.11.5 Energy and Fatigue VAS ...................................................................................... 170

8.11.6 Treatment/Test Meal Palatability .......................................................................... 171

8.11.7 Test Meal Record .................................................................................................. 172

8.11.8 Blood Glucose Record .......................................................................................... 173

xiv

LIST OF TABLES

TABLE 4.1. Exp 1: Composition of treatments consisting of white beans with tomato sauce. ... 32

TABLE 4.2. Exp 2: Composition of treatments consisting of a tomato-based beverage. ............ 32

TABLE 5.1. Exp 1: Subject characteristics. ................................................................................. 41

TABLE 5.2. Exp 2: Subject characteristics. ................................................................................. 42

TABLE 5.3. Exp 1: Effect of sodium content of a solid food (beans) on treatment and test meal

palatability1 ................................................................................................................................... 44

TABLE 5.4. Exp 2: Effect of sodium content of a beverage (tomato juice) on treatment and test

meal palatability1 .......................................................................................................................... 44

TABLE 5.5. Exp 1: Effect of sodium content of a solid food (beans) on food, sodium and water

intakes1 .......................................................................................................................................... 46

TABLE 5.6. Exp 2: Effect of sodium content of a beverage (tomato juice) on food, sodium and

water intakes1 ................................................................................................................................ 46

TABLE 5.7. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal average

appetite scores at each measurement time1 .................................................................................. 49

TABLE 5.8. Exp 2: Effect of sodium content of a beverage (tomato juice) on pre-and post-meal

average appetite scores1 ............................................................................................................... 50


appetite areas under the curve (AUC)1 ......................................................................................... 51

TABLE 5.10. Exp 2: Effect of sodium content of a beverage (tomato juice) on pre-meal, post-

meal and cumulative average appetite areas under the curve (AUC)1 ........................................ 51

xv

TABLE 5.11. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal thirst ratings1

....................................................................................................................................................... 54


thirst ratings1 ................................................................................................................................ 55

TABLE 5.13. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal thirst areas

under the curve (AUC)1 ................................................................................................................ 56


meal and cumulative thirst areas under the curve (AUC)1 ........................................................... 56

TABLE 5.15. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal blood glucose

concentrations1 ............................................................................................................................. 59


blood glucose concentrations1 ...................................................................................................... 60


areas under the curve (AUC)1 ....................................................................................................... 61


meal and cumulative blood glucose areas under the curve (AUC)1 ............................................. 61


physical comfort scores1 ............................................................................................................... 63


average physical comfort scores1 ................................................................................................. 64

TABLE 5.21.Exp 1: Effect of sodium content of a solid food (beans) on pre-meal average

physical comfort areas under the curve (AUC)1 ........................................................................... 65


meal and cumulative average physical comfort areas under the curve (AUC)1 ........................... 65

xvi

TABLE 8.1. Exp 1: Effect of pre-meal water intake on treatment and test meal palatability1 .... 93

TABLE 8.2. Exp 1: Effect of pre-meal water intake on food, sodium and water intakes1 ........... 93

TABLE 8.3. Exp 1: Effect of pre-meal water intake on pre-meal average appetite scores1 ........ 94

TABLE 8.4. Exp 1: Effect of pre-meal water intake on pre-meal average appetite areas under

the curve (AUC)1 ........................................................................................................................... 95

TABLE 8.5. Exp 1: Effect of pre-meal water intake on pre-meal thirst ratings1 ......................... 96

TABLE 8.6. Exp 1: Effect of pre-meal water intake on pre-meal thirst areas under the curve

(AUC)1 ........................................................................................................................................... 97

TABLE 8.7. Exp 1: Effect of pre-meal water intake on pre-meal blood glucose concentrations198

TABLE 8.8. Exp 1: Effect of pre-meal water intake on pre-meal blood glucose areas under the

curve (AUC)1 ................................................................................................................................. 99

TABLE 8.9. Exp 1: Effect of pre-meal water intake on pre-meal average physical comfort

scores1 ......................................................................................................................................... 100


areas under the curve (AUC)1 ..................................................................................................... 101

TABLE 8.11. Exp 1: Screening food frequency questionnaire data1 ......................................... 102

TABLE 8.12. Exp 1: Effect of sodium content of a solid food (beans) on past 24-hour food

intake, physical activity and stress levels1 .................................................................................. 102


intakes with treatment pleasantness as a covariate1................................................................... 103


intakes with baseline average appetite as a covariate1 .............................................................. 103

xvii

TABLE 8.15. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal desire-to-eat

scores at each measurement time1 .............................................................................................. 104



TABLE 8.17. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal hunger scores

at each measurement time1 ......................................................................................................... 106

TABLE 8.18. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal hunger areas

under the curve (AUC)1 .............................................................................................................. 107

TABLE 8.19. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal fullness scores

at each measurement time1 ......................................................................................................... 108

TABLE 8.20. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal fullness areas


TABLE 8.21. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal prospective

food intake scores at each measurement time1 ........................................................................... 110


food intake areas under the curve (AUC)1 .................................................................................. 111

TABLE 8.23. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal nausea scores1

..................................................................................................................................................... 112

TABLE 8.24. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal nausea areas


TABLE 8.25. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal stomach pain

scores1 ......................................................................................................................................... 114



xviii

TABLE 8.27. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal wellness

scores1 ......................................................................................................................................... 116

TABLE 8.28. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal wellness areas


TABLE 8.29. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal flatulence

scores1 ......................................................................................................................................... 118



TABLE 8.31. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal diarrhea

scores1 ......................................................................................................................................... 120

TABLE 8.32. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal diarrhea areas


TABLE 8.33. Exp 2: Screening food frequency questionnaire data1 ......................................... 122

TABLE 8.34. Exp 2: Effect of sodium content of a beverage (tomato juice) on past 24-hour food

intake, physical activity and stress levels1 .................................................................................. 122


water intakes with average treatment palatability as a covariate1 ............................................. 123


desire-to-eat ratings1 .................................................................................................................. 124


meal and cumulative desire-to-eat areas under the curve (AUC)1 ............................................. 125


hunger ratings1 ............................................................................................................................ 126

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meal and cumulative hunger areas under the curve (AUC)1 ...................................................... 127


fullness ratings1 ........................................................................................................................... 128


meal and cumulative fullness areas under the curve (AUC)1 ..................................................... 129


prospective food intake ratings1 .................................................................................................. 130


meal and cumulative prospective food intake areas under the curve (AUC)1 ............................ 131


nausea ratings1 ............................................................................................................................ 132


meal and cumulative nausea areas under the curve (AUC)1 ...................................................... 133


stomach pain ratings1 ................................................................................................................. 134


meal and cumulative stomach pain areas under the curve (AUC)1 ............................................ 135


wellness ratings1 ......................................................................................................................... 136


meal and cumulative wellness areas under the curve (AUC)1 .................................................... 137


flatulence ratings1 ....................................................................................................................... 138

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meal and cumulative flatulence areas under the curve (AUC)1 ................................................. 139


diarrhea ratings1 ......................................................................................................................... 140


meal and cumulative diarrhea areas under the curve (AUC)1 ................................................... 141

TABLE 8.54. Exp 2: Relationships between food intake and dependent measurements ........... 142

TABLE 8.55. Exp 2: Relationships between water intake and dependent measurements ......... 143

TABLE 8.56. Exp 2: Relationships between subjective average appetite and dependent

measurements .............................................................................................................................. 144

TABLE 8.57. Exp 2: Relationships between subjective thirst and dependent measurements ... 145

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LIST OF FIGURES

Figure 2.1.. .................................................................................................................................... 13

xxii

LIST OF ABBREVIATIONS

AI Adequate Intake

ANOVA Analysis of Variance

AUC Area under the Curve

BG Blood Glucose

BMI Body Mass Index

CCK Cholecystokinin

FDA Food and Drug Administration

FI Food Intake

GI Glycemic Index

GIP Gastrointestinal Peptide

GLP-1 Glucagon-Like Peptide

IOM Institute of Medicine

MIN Minutes

PYY Peptide YY (3-36)

SA Subjective Appetite

SEM Standard Error of the Mean

VAS Visual Analogue Scales

WI Water Intake

1

CHAPTER 1 INTRODUCTION

1.1 Introduction

Sodium, an essential electrolyte, is naturally present in foods and has been exploited by humans

for millennia as a natural food preservative and flavouring agent. Not surprisingly, continuous

regard for this mineral‟s applications encouraged drastic increases in dietary intakes around the

world. Current global sodium intake ranges between 2300 and 4900 mg daily [1], which

surpasses dietary recommendations for individuals across all age groups. Because approximately

77% of sodium intake originates from processed foods [2], governments and health institutions

worldwide are aggressively campaigning for sodium reduction in the food supply [1, 3-6].

Excess sodium intake is a dietary risk factor for hypertension [7, 8] and cardiovascular mortality

[5]. In addition to elevated blood pressure, nutritional surveys associate habitual savoury food

intake (FI) with higher energy intake in adults [9] and BMI in children [10]. Excess sodium may

also indirectly contribute to energy imbalance by stimulating thirst and consequent intake of

caloric beverages in lieu of water [11-14]. Thus, chronically high dietary sodium intake may

influence other features of the metabolic syndrome including obesity and insulin resistance.

However, the physiological origins of the association of sodium content of chronic diets with

excess energy intake have received little examination. A simple way to begin understanding this

relationship is by investigating the effects of acute sodium ingestion on FI and water intake (WI).

Some authors have found that sodium delays gastric emptying [15, 16], which increases satiety

[17], while others have paradoxically observed increased hunger in healthy adults independently

from taste [18]. In addition, sodium directly affects thirst and fluid intake regulation but it is not

yet known if sodium increases subsequent WI at a later meal, which may influence FI at the

same meal. Sodium and glucose are also absorbed together in the small intestine [19-21], which

has sparked the hypothesis that sodium increases glucose absorption [22-25]. However, acute

studies have reported that sodium leads to both postprandial hyperglycemia [22, 26] and null

effects [27, 28]. The lack of concordance may depend in part on whether sodium was

administered in a solid food or a beverage; and sodium‟s effects on gastric emptying [16].

2

The overall hypothesis for this thesis was that sodium content of a food or beverage increases

acute subjective appetite (SA), thirst, ad libitum FI and WI, and blood glucose (BG)

concentrations. Therefore, the objective of this thesis was to evaluate the acute effects of a range

of sodium added to either a solid food (Experiment 1) or beverage (Experiment 2) on subjective

measures (appetite and thirst) and quantitative intake of food and water intake and on

postprandial blood glucose (BG) in healthy young men.

3

CHAPTER 2 LITERATURE REVIEW

2 2.1 Introduction

The literature review begins with a brief history of sodium in the human diet (2.2) followed by

recommended sodium intakes (2.3) and top dietary sources (2.4). The fourth section summarises

food applications of salt and other sodium compounds (2.5). Next, an overview is presented on

sodium‟s biological functions and health risks (2.6). The final three sections address sodium‟s

effects on fluid regulation (2.7), energy intake (2.8) and glycemic control (2.9).

2.2 History of Sodium in the Human Diet

Sodium has played a significant socio-cultural, economic and epicurean role in the expansion of

civilizations [29]. During the Palaeolithic Era, nomadic hunters and gatherers consumed nearly

600 mg/d of sodium naturally present in fruits, vegetables, nuts, and lean game and fish [30, 31].

However, this dietary pattern changed with the onset of the Neolithic Revolution, which marked

the development of an agrarian, settled lifestyle due to the domestication of animals and plants.

Food surpluses resulted and encouraged nascent food technologies and preservation methods like

salting [29].

Historians traced the harvesting origins of sodium chloride to 6000 BCE China, an event trailed

by its discovery to cure meats in 3000 BCE Egypt [29, 32]. Sodium thus gained a steady

entryway into the human diet by allowing societies to expand their food stores. As demand for

this commodity increased, exploration and colonization took place. In turn, trade with the New

World between the 13th

and 19th

centuries sustained salt‟s function as a food preservative for

curing and fermenting meats and fish [29]. Indeed, high consumption of dried cod from the

Americas led to staggeringly high sodium intakes, up to 23000 mg per day for 16th

century

Swedes [31]. With the arrival of the Industrial Revolution, dietary and sodium intake patterns

once again changed because of the introduction of processes like canning and refrigeration that

prompted the development of pre-packaged foods [32]. At this point, sodium intake started to

decline [32] but again crept up as consumption of convenience foods spiked in the 20th

century.

4

2.3 Current and Recommended Sodium Intakes

As noted above, sodium is a dietary element that is being consumed above physiological

requirements. The Institute of Medicine (IOM) established adequate intakes (AI) between 1000

and 1500 mg, the higher end recommended for individuals 14 to 50 years old [33], although

people can thrive on as little as 200 mg daily [34]. The AIs can be achieved simply through a

diet of mixed animal- and plant-based foodstuffs [30]; and are sufficient to buffer against severe

sodium sweat losses. Given their lower energy requirements, older adults are recommended

slightly lower sodium intakes: 1300 mg/d for adults 50 to 70 years of age; and 1200 mg/d for

adults aged 71 and older. Since sodium is mostly consumed with chloride, it is set at a molar

equivalent basis with sodium. For instance, individuals 14 to 50 years old should attain an intake

of 2300 mg/d of chloride. Overall, the recommended intake for sodium chloride (salt) is 3800

mg/d [33].

Adults should not exceed 2300 mg of sodium daily, which is the tolerable upper intake level

(UL) for individuals 14 to 50 years old. Most individuals, however, consume above the

recommended intakes and ULs. One of the first studies that estimated global sodium intakes was

the large-scale epidemiological study INTERSALT (1985-87), which sampled 10079 men and

women aged 20-59 from 52 populations around the world. INTERSALT revealed that ruralised

groups like the Yanomamo aboriginal tribe of Brazil consumed 400 to 1200 mg sodium whereas

intake was greater than 3560 mg daily in urbanized, industrialized communities [7]. Similarly,

the study INTERMAP found that adults living in China, Japan, the United Kingdom and the

United States [35] consume on average 3934 mg; however, sodium intake for men is higher than

for women, perhaps due to higher intake of calories or sodium-dense foods [36]. Mean global

daily intakes have been estimated to range between 2300 to 4600 mg [1] while the 2004

Canadian Community Health Survey (CCHS) estimated average intake to be 3400 mg/d for

Canadians [37]. Furthermore, 45 to 99% of the population 9 years of age and older consumes

sodium in excess of their age-specific ULs, with males consuming more sodium than females.

5

2.4 Dietary Sodium Sources

Nearly 77% of sodium intake is derived from processed convenience foods whereas home-

cooked meals account for 5%. Only 6% of sodium is added at the table and 12% occurs naturally

in foods [2]. Processed foods span a wide range of sodium density and sources vary around the

world. For instance, grain products like cereals and breads along with processed meats are the

greatest sources of household sodium in the United Kingdom and United States. In Japan, dietary

sodium is mostly derived from processed foods like salted vegetables (9.8%), salted fish (9.5%)

and breads and noodles (4.6%); and the greatest sources are soy-based products like soy sauce

(20%) and miso soup (9.7%). Compared to Japan, fewer high-sodium foods are consumed in

China and most sodium is added to home-cooked meals or at the table (75.8%) [35]. In Canada,

the top three dietary sources are: breads (14%); processed meats (9%); and vegetables (canned,

pickled and fresh), tomatoes and vegetable juice (8%) [38].

2.5 Food Uses of Salt and Other Sodium Compounds

Sodium‟s two overarching functions are preservation and sensory enhancement. Its most well-

known compound is table salt, which contains 40% sodium and 60% chloride in its crystalline

form1. It is an inexpensive and multifunctional ingredient accounting for 90% of humans‟

sodium intake [2]. For instance, in bread, salt controls yeast growth and fermentation rate and

increases resistance to extension and extensibility to prevent poor texture [39]. Manufacturers

add salt to canned vegetables and pulses to increase their rate of softening [40, 41]; while in

cheese, salt controls ripening, modulates enzymatic activity and develops flavour [42].

2.5.1 Sodium Chloride and Prevention of Food Spoilage

Microorganisms are present in all foods but measures can be taken to hamper their growth and

prevent food-borne illnesses and spoilage. Salting in particular has played a vital role given its

1 The conversion factors for sodium, chloride and sodium chloride are their respective molecular weights 23, 35.5 and 58.5. For

instance, 100 mmol of salt is equivalent to 5850 mg and contains 2300 mg sodium and 3550 mg chloride. To convert milligrams

of sodium to milligrams of salt, the amount of sodium is multiplied by a factor of 2.54. For example, 200 mg of sodium equates

to 500 mg of 0.5 g of salt. Also, 1 mmol of sodium equals 1 mEq and nearly 2300 mg of sodium are present in 1 teaspoon.

6

ability to decrease water activity [43, 44]. A product stored in a humid environment will absorb

water from the air and undergo increased water activity, a measure of water content. Due to its

osmotic properties, sodium ions on the food surface draw intracellular water inwards. Reducing

water activity via salt causes microorganisms‟ cell membranes to detach from their cell walls

(plasmolysis) and halt growth. A hypertonic environment created by sodium causes

microorganisms like Clostridium botulinum in processed meats and cheeses to shrivel and

hinders their production of toxins because of reduced nutrient utilization and DNA replication.

2.5.2 Salt Taste Perception and Food Palatability

Salt is one of five taste modalities recognized, with the others being bitter, sweet, sour and

umami (“savoury” or “meaty”). Salt taste transduction involves projections localized at the tip

and sides of the tongue that are partly comprised of epithelium sodium channel (ENaC) subunits

[45]. After ingestion, sodium ions flood the tongue and create an electrochemical gradient

outside of taste cells. This gradient drives sodium ions to cross the apical membrane-bound

ENaC and enter cells, followed by active pumping of sodium outside of cells across the

basolateral membrane by Na+-K

+-ATPase transporters. Without exposure to sodium ions, salt

acuity and preference are affected. In one study, young adults given un-tasted high-salt tablets

for two weeks experienced reduced acuity for salt while preferring lower amounts as measured

by ad libitum salting of unsalted tomato juice and ratings of pre-salted tomato juice [46].

ENaC is also permeable to potassium and lithium ions [4]. However, an unadulterated salty taste

results from sodium whereas salt substitutes like potassium chloride generate bitterness and a

weaker salty taste [47]. For this reason, potassium chloride is not used alone but rather about

30% is blended with salt [4] and bitter-masking agents [48, 49] to maintain palatability in

sodium-reduced foods.

Salt taste is a decisive factor in consumer food selection and acceptance; hence, finding optimal

amounts of salt to add to foods is critical for eliciting consumer satisfaction [50]. Sodium not

only imparts its own distinctive taste but also intensifies and complements other flavours to

7

round out palatability [43, 50]. For instance, salt balances acidic and bitter qualities while also

enhancing meat flavours and decreasing sweetness of sugars [50].

Epitomizing its sensory application are savoury snacks like chips, popcorn and extruded

products. Savoury snacks are chiefly made from flour-, potato- or corn-based ingredients

naturally low in sodium and bland [50]. Thus, they require the addition of salt and other

seasonings to increase their palatability. In contrast to breads and cereals that have salt

incorporated into their matrix, manufacturers prefer adding salt to the surfaces of finished snacks

to elicit an intense salty taste. Also, salt is used as a carrier for seasonings to ensure that flavours

and colours are evenly distributed. However, the same amount of salt in cereals or bread is often

undetected because it is masked by the food matrix.

2.5.3 Additional Sodium Compounds and Associated Health Risks

Although sodium chloride is broadly used, sodium is also available in other well-known forms

including sodium nitrate and monosodium glutamate (MSG).

2.5.3.1 Sodium Nitrite

Sodium nitrite (NaNO2) is an essential ingredient used for flavour, colour maintenance of

preserved meats and inhibition of endospore- and neurotoxin-producing bacteria like Clostridium

botulinum [51]. Nitrite is naturally found in dark leafy greens and animal tissue, the latter

resulting from the metabolism of the neurotransmitter nitric oxide (NO).

NO combines with myoglobin to form nitrosomyoglobin, which imparts a deep red colour to

cured meats [52]. However, NaNO2 reacts with amines in cured meats to form nitrosamines,

which when exposed to gastric acid or high cooking temperatures, are converted to diazonium

ions that elicit cell damage [51, 53]. Consequently, alarm has been raised over its carcinogenic

potential and link to stomach cancer but research remains equivocal [54-56].

At present, the FDA legally permits 1 ounce of NaNO2 per 100 pounds of dry, cured meat; it is

fatal at a dose of 22 to 23 mg/kg of body weight in humans [51]. For perspective, a person

weighing 70 kg would need to eat 19 pounds of cured meats to derive enough NaNO2 to

8

experience toxicity. In reality, most nitrite intake comes from vegetables and other sources [53,

54] and should not pose a substantial health risk.

2.5.3.2 Monosodium Glutamate (MSG)

MSG (C5H8NNaO4) is the sodium salt of L-glutamic acid, a non-essential amino acid that

represents 10% to 25% of protein in animal and vegetable sources [57]. Glutamic acid itself has

several functions including: providing energy to gastrointestinal cells during digestion; and

acting as both an excitatory neurotransmitter and precursor for the inhibitory neurotransmitter γ-

aminobutyric acid (GABA) [58]. Above all, MSG is widely used as a flavour enhancer and salt

substitute given glutamate‟s ability to induce umami [59]. In fact, it contributes to daily sodium

intake for Japanese, Korean and Taiwanese populations consuming up to 3000 mg MSG daily

(408 mg sodium) from hydrolyzed vegetable protein products like soy sauce [35, 60].

To date, MSG is not considered a health hazard [57] but is known for inducing obesity in animal

models. Adult mice and rats treated with MSG soon after birth display a multitude of endocrine

and metabolic abnormalities arising from hypothalamic lesions afflicting FI and appetite

regulatory neurons [61]. These include: hyperinsulinemia; decreased insulin-sensitive glucose

mobilisation in adipocytes; adipocyte hypertrophy; and abnormal angiotensin II receptors with

low binding capacity [62]. The latter effect may impair sodium and water balance regulation.

In humans, epidemiological research hints at a positive relationship between high MSG intake

and higher BMI [60]. However, a relationship between MSG and obesity remains unproven for

humans because glutamate is metabolised rapidly in the intestine, thus failing to raise plasma

glutamate concentrations to levels known to cause hypothalamic damage in rats [63]. The

harmful effects attributed to MSG may arise from synergism between the sodium cation and

glutamate anion but this requires further investigation.

2.6 Sodium: From Vital Nutrient to Health Risk Factor

Beyond its sensory effects, sodium is a major extracellular cation and plays several vital

biological functions. Almost all ingested sodium is absorbed and freely transported in blood to

9

carry out its functions [64]. Sodium maintains electrical potential in excitable cells including

myocytes and neurons [65] and contributes to acid-base balance. Its active transport by Na+/K

+-

ATPases also creates a concentration gradient across the cell membrane that is needed for

nutrient uptake by intestinal and renal cells. At the crux of sodium‟s functions is its

interdependence with potassium and water in electrolyte and fluid balance.

Body water is distributed as intracellular fluid (ICF) and extracellular fluid (ECF), segregated by

a semi-permeable barrier of cell membranes that allows water to move freely across [66].

Sodium, potassium and other impermeable solutes are restricted from crossing cells without

active transport and thus predominantly remain on either side. This is accomplished by

ubiquitous Na+/K

+-ATPases that allocate sodium mostly to extracellular spaces while

concentrating potassium inside cells. Because of this distribution, sodium and potassium are

osmotically active solutes (effective osmolytes) and they contribute to the effective plasma

osmolality that exerts an osmotic drive (mOsm/kg). When ICF and ECF are unbalanced, the

osmotic drive forces water to flow from the milieu with lower to higher solute concentration

(osmosis) to equalise osmolality across cell membranes. As a result, cells lose water and shrink

when plasma osmolality rises but gain water and swell when plasma osmolality decreases.

Normal operation of bodily tissues depends on appropriate solute concentrations and fluid

volumes being established outside and inside cells [65]. Otherwise, dramatic changes in sodium

and fluid intake may induce cell damage and even death [64].

Excess sodium intake dysregulates fluid and blood pressure control. In the acute, a salty meal

increases plasma osmolality and causes water to exit cells. Integrated neural, cardiovascular and

renal mechanisms are then activated to reverse changes in water compartments and return plasma

osmolality to normal (280 to 295 mOsm/kg) [67]. Although a time frame is not well-documented

in humans, the homeostatic responses to a hyperosmotic condition occur rapidly in animals,

perhaps within 10 to 15 min in rats [68]; and also likely depend on the amount of sodium

ingested. One caveat is that the human kidney is designed to conserve sodium and has not

adapted to high sodium intake. Instead, sodium is poorly excreted and excess is stored in the

body. Over time, this leads to expansion of ECF volume and increased blood pressure. This

effect is initially countered by the pressure-natriuresis renal mechanism [69], a negative feedback

10

system that increases sodium and water excretion (natriuresis) to help lower blood pressure and

prevent acute sodium toxicity. However, sodium also leads to ineffective potassium conservation

by the kidneys and induces vasoconstrictive factors that increase peripheral resistance, which

further contribute to hypertension.

Chronically high sodium intake elevates blood pressure, especially in predisposed individuals.

Conditions like obesity, insulin resistance, and salt sensitivity enhance the hypertensive effects

of sodium. In this manner, sodium also poses a high risk for the development of cardiovascular

disease. It has been estimated that an increase in dietary sodium intake by 2300 mg increases

systolic and diastolic blood pressures by 3 to 6 mm Hg and 0 to 3 mm Hg, respectively [7]. As a

result, health organisations and governments worldwide are promoting sodium reduction

strategies to reduce cardiovascular morbidity and mortality [1, 5, 6]. An interim goal was

established by Canada‟s Sodium Working Group (SWG) to reduce dietary sodium intake to 2300

mg per day by 2016 and eventually between 1500 and 2300 mg [3].

Aside from contributing to hypertension, it has been suggested that high sodium intake affects

other parameters of the metabolic syndrome, obesity and insulin resistance. The following three

sections will discuss the available evidence linking sodium with relevant biomarkers: fluid intake

and thirst (2.7); energy intake regulation (2.8); and glycemic control (2.9).

2.7 Sodium, Increased Fluid Intake and Energy Balance

As described, plasma osmolality and volume fluctuations must be regulated to ensure normal

bodily functions. Elaborate regulatory mechanisms have thus evolved to respond to changes in

intra- and extracellular mediums. An essential component for survival is the stimulation of thirst

and fluid intake after sodium ingestion. Intake of a salty meal prompts water-seeking behaviours

to re-establish ICF and ECF isotonicity yet evidence from dietary studies suggest that individuals

drink caloric beverages in lieu of water to quench thirst [11-14]. It is also unclear if acute sodium

intake affects ad libitum fluid intake at a later meal. Through fluid intake, sodium may indirectly

contribute to energy imbalance and other metabolic derangements.

11

2.7.1 Sodium, Intracellular Thirst and Fluid Regulation

Thirst is often described as a “sensation of dryness in the mouth and throat” that motivates

beings to crave and imbibe fluids. Thirst also arises as a regulatory response to a deficit in body

fluids (dehydration) or high sodium intake. In this light, thirst is more appropriately defined as a

physiological state originating from extracellular or intracellular fluid losses that is behaviourally

manifested as increased fluid intake for rehydration (FIGURE 2.1). For instance, hypovolemia

from a severe loss of body fluids or decreased plasma osmolality from very low sodium intake

induces extracellular (volumetric) thirst [70, 71]. The renin-angiotensin-aldosterone hormonal

system is activated to increase blood volume and pressure through fluid intake and prevent renal

sodium chloride and water losses. In daily life, thirst also arises after ingestion of a salty meal.

In an acute setting, high sodium intake leads to systemic hypertonicity by elevating plasma

sodium concentration above intracellular solute concentration. An osmotic stimulus like sodium

then drives intracellular water into ECF to even out solute concentrations across their

membranes, which causes intracellular (osmometric) thirst [72]. Changes in osmolality or

tonicity can be small (as low as a 1% to 2% increase) yet still result in the most potent thirst

stimulus. Elevated plasma osmolality is sensed by osmoreceptors distributed throughout the

body. It appears that vagal nerve endings linked to the gut are the first to detect changes [73]

followed by central receptors in the fluid and electrolyte control nodes in the subfornical organ

and medial preoptic nucleus of the hypothalamus [74]. These areas of the brain prompt

individuals to search for water to drink. Ingestion of water is later perceived by specialized

receptors in the throat (oropharynx) that signal the brain to diminish the drive for fluid intake to

prevent plasma osmolality from decreasing below the physiological set point (280 to 300

mOsm/kg) [75].

When central osmoreceptors shrink, they also stimulate the release of antidiuretic hormone

(ADH) beginning at a plasma osmolality of 280 mOsm/kg [67]. ADH is a pre-pro-hormone

produced by the hypothalamus and released by the posterior pituitary. It causes moderate and

temporary vasoconstriction [70], which may become permanent and contribute to increased

blood pressure. Above all, ADH is released to conserve water by decreasing renal sodium and

water excretion [70]. To increase active water re-absorption, ADH mobilizes water channels in

12

the collecting tubule epithelium via binding to its G protein-coupled receptors. ADH also

increases salt re-absorption at the ascending limb of the loop of Henle, so that a higher sodium

concentration on the apical side drives osmosis through new water channels [70]. These steps

eventually increase urea concentration and decrease urinary output.

Water reabsorption cannot fully restore plasma osmolality. ADH also functions as a powerful

dipsogen [71] that stimulates the sensation of thirst to promote WI. In healthy adults, ADH is

released in direct proportion to increasing plasma osmolality (1% to 2% change above basal

levels) until it falls below the osmotic threshold (295 mOsm/kg) [67]. However, inappropriate

ADH secretion causes excessive fluid intake that can induce hyponatremia and extracellular

thirst [76]. This state is known as euvolemic hyponatremia, which is characterized by normal

total body sodium and normal ECF but increased total body water. Individuals may seek salty

foods to normalize their plasma levels and excrete excess ECF. The search for salty foods is also

known as “salt appetite” and is normally attributed to activation of the renin-angiotensin-

aldosterone system during times of sodium restriction [31, 77].

13

FIGURE 2.1. Normal thirst comprising both intra- and extracellular mechanisms. Ingestion of

sodium increases plasma osmolality, which is sensed by specialised cells that signal intracellular

thirst as outlined on the left-hand side. The right-hand side illustrates that a reduction in blood

volume or pressure stimulates extracellular thirst. These two different stimuli activate distinct

hormones that overlap in their regulation of: 1) renal reabsorption of sodium or water; 2)

vasoconstriction; and 3) stimulation of brain thirst centres to induce ingestion of water. This

figure is modified from Thornton [66].

14

2.7.2 The Relationship between Fluid and Energy Intake

Water is considered to be the fluid that best quenches thirst as soon as its ingestion is detected by

oropharyngeal osmoreceptors [75]. However, it appears that many people drink caloric

beverages in lieu of water. Americans have experienced parallel increases in sodium intake

(55%), soft drink consumption (45%) and overweight/obesity rates (61% for men and 52% for

women) since 1983 [30]. In children living in the United Kingdom, caloric soft drinks accounted

for 31% of total fluid intake whereas water only contributed to 9%. [12]. A strong positive link

was also found between high sodium and high sugar-sweetened soft drink intakes (r = 0.12, P <

0.001) after adjusting for body weight and sex. The authors then predicted that a daily reduction

of 390 mg sodium would reduce total fluids by 100 g and caloric soft drinks by 27 g, which may

impact weight status over time and reduce the risk of obesity. One concern is that liquid calories

ingested for hydration are not satiating [78], which can override appetite regulatory mechanisms

and prompt unrestrained intake of solid calories [79]. For example, BMI increased as soft drink

consumption increased (r = 0.07, P < 0.01) in obese Italian children [10]. Overweight individuals

generally tend to drink less water than lean individuals [13]. It follows that lower sodium

ingestion may reduce fluid intake [80] and perhaps liquid calories.

The above associations do not confirm that individuals drank fluids and were overweight

because sodium induced intracellular thirst. Fluid intake is associated with socio-cultural

customs and other non-physiological factors. Another possibility is that fluid intake led to

euvolemic hyponatremia, causing people to eat savoury foods to rebalance their plasma

osmolality. Beverage and food portion sizes have also increased over time, a trend that has been

associated with rising rates of obesity. Perhaps changes in the food supply promote a link

between sodium, fluid intakes and overweight status that is unrelated to physiological thirst.

Acute trials have shown that serving a larger portion of solid food leads to increased energy

intake [81]. Similarly, in a clinical setting, normal and overweight adults drink more fluids when

served beverages 50% greater in volume irrespective of their energy content [82]. It seems

natural that consumers exposed to large portion sizes on the marketplace are ingesting copious

amounts of sodium from salty foods and beverage intakes, which are both trends that encourage

a positive energy balance. A missing piece of this puzzle entails understanding why individuals

drink more caloric beverages and less water and if sodium plays a role.

15

Many studies have examined the relationship between fluids and energy balance to determine if

beverage type, volume and energy content affect FI at the same meal. However, epidemiological

observations did not assess patterns of fluid intake to determine if fluids were ingested randomly

or with a salty snack as would be expected. If sodium intake was the underlying factor for the

links between fluids and obesity, then fluid intake would be expected to increase in response to

sodium intake rather than at any time. It is estimated that 70 to 80% of fluid intake including

water occurs periprandially (consumed with a snack or meal) [13]. It is unclear, however, if this

association arises because thirst is stimulated by the salt content of the meal; the greater osmotic

pressure in the gut arising from food components and digestive products; or dietary habits. This

may be better understood if it was known how quickly sodium intake affects ad libitum WI. A

study investigating the acute effects of sodium loading (92 versus 2300 mg) in healthy adults

demonstrated that 2300 mg sodium significantly increased plasma sodium levels 30 min after

sodium ingestion [83]. In parallel, plasma osmolality increased from 287.9 to 293.2 mOsm/kg

(an approximate 2% increase) at 30 min after baseline, which was above the osmotic threshold

for ADH release. Plasma sodium and osmolality remained elevated until 90 min after baseline

and declined thereafter. Neither ADH nor ad libitum WI were measured but these findings

support the idea that sodium intake can prompt fluid intake within 30 min of ingestion as a result

of changes in plasma osmolality signalling intracellular thirst.

It remains to be investigated if people respond to sodium by drinking water or other fluids at a

subsequent meal within the above time frame (i.e. 30 to 90 min), and if this influences

simultaneous FI. Drinking water during a meal is thought to reduce FI due to gastric distention

but this has not been well-documented. Clinical trials are thus needed to understand the role of

sodium in the relationship between fluid intake and energy balance as well as the independent

effects of water and other fluids on energy balance (Appendix I).

2.8 Sodium and Energy Intake Regulation

Health experts advise individuals to limit their intake of salty foods as one dietary strategy to

lose weight and mitigate co-morbidities [84]. In addition to the relationship between fluid intake

and weight, foods high in sodium are usually processed, high in fat and consumed in large

16

portion sizes, leading to a parallel increase in sodium and energy intake. Nevertheless, several

lines of evidence suggest that high sodium intake directly affects satiety although it is not yet

confirmed in what direction. One limitation is that the effects of sodium on FI at a later meal

have not been assessed.

2.8.1 Obesity and Energy Balance Overview

Obesity is a serious global [85] and local health concern. According to the 2004 CCHS, nearly

two-thirds of Canadian adults are overweight or obese [86], which increases their risk for the

onset of impaired glucose tolerance, insulin resistance, dyslipidemia and hypertension [87]. This

is a multi-etiological medical condition but it is traditionally viewed as an outcome of chronic

energy imbalance resulting from excessive intake compared to expenditure. Complex peripheral

and central signals are involved in regulating FI. For instance, nutrient ingestion first stimulates

gastric stretch receptors that influence gastric emptying rate and triggers the release of

anorexigenic hormones like cholecystokinin (CCK), peptide tyrosine tyrosine (PYY), glucose-

dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1) by enteroendocrine

cells [88]. These pre-absorptive gut peptides have numerous targets including afferent nerve

terminals in the brain mostly stemming from the vagus nerve. By acting on central areas

regulating FI, these peripheral signals provide the brain with information that allows it to control

meal intake size, termination of the meal (satiation) and energy expenditure through neural

circuits projecting onto the gut, adipose and muscle [89].

2.8.2 Savoury Foods and Weight Status

There is a growing opinion that sodium is positively linked with obesity. On the one hand, the

association between sodium and energy intakes may arise from the food applications of salt. By

increasing palatability, sodium appears to increase energy intake and weight gain as a result of a

higher preference for saltier-tasting foods and their frequent consumption. In one observational

study [10], obese Italian children reported eating more savoury than sweet snacks per week

compared to normal weight children. Also, BMI increased as savoury snack intake increased (r =

17

0.06, P < 0.05) and logistic regression suggested that each weekly serving of savoury items

increased the likelihood of obesity by 2%.

In contrast, food preference for neither savoury or sweet items nor energy intakes were different

between free-living obese and normal weight adults in England [9]. Calories were also mostly

derived from savoury foods (~900 kcal) compared to sweet (~200 kcal), sour (~375 kcal) and

bitter (~675 kcal) foods. Thus, it is not clear that the sensory properties of salt or high salt

content of foods account for increased energy intake and obesity.

2.8.3 Sodium Absorption and Delayed Gastric Emptying

In order to understand sodium‟s potential physiological effects on energy balance, it is important

to understand its course in the gastrointestinal tract. Sodium absorption mostly occurs in the

jejunum and ileum of the small intestine. Jejunal sodium movement against a small

concentration gradient occurs in tandem with water flow [19]. Specifically, sodium and water are

absorbed when jejunal luminal sodium is at par with normal plasma sodium levels (290

mOsm/kg); below this value, sodium is secreted. In the ileum, however, sodium absorption

proceeds against a steep concentration gradient independently of water absorption or secretion.

Once sodium is absorbed, it is actively pumped out of intestinal cells and into circulation by

basolateral Na+/K

+-ATPases. In order to prevent too much sodium from entering blood, a highly

osmolar (hypertonic) food or beverage stimulates a reflex to delay gastric emptying and nutrient

absorption [15]. An early study [16] on gastric emptying in adult volunteers observed that

increasing the osmotic concentration of sodium chloride (NaCl) or sodium bicarbonate

(NaHCO3) (up to 250 mOsm or 2155 mg of sodium in 750 mL of distilled water) and sodium

sulphate (Na2SO4) (up to 50 mOsm in 750 mL of distilled water) increased the amount of fluid

emptied from the stomach over 20 min. However, concentrations above these values increased

the volume of fluid recovered from the stomach for all the sodium salts tested, reflecting slower

emptying with higher osmotic concentrations. Gastric emptying refers to the action of the

stomach contents emptying into the small intestine. Hypertonicity relative to the stomach causes

water to exit cells and enter the lumen. Specialised sodium-sensitive cells (osmoreceptors) are

18

located in hepatoportal vessels extending from the stomach to the liver, which also connect to the

hepatic branch of the vagus nerve. High sodium intake causes these cells to shrink as they lose

water and send signals to the nucleus of the solitary (NTS) located in the brainstem via vagal

neurons. Information sent to the NTS is then relayed to hypothalamic regions that regulate fluid

and electrolyte absorption in the small intestine [90]. Thus, a hypertonic food or beverage

stimulates vagal neurons to suppress sodium and water uptake.

This reflex arc stimulated by hypertonicity also suggests that, because of delayed gastric

emptying, higher sodium ingestion may reduce FI, induce satiety and lower postprandial BG

concentrations. In healthy normal weight adults, consumption of sourdough bread providing 50 g

of available starch and containing an organic salt (sodium proprionate) lowered both plasma BG

and insulin responses over 180 min compared to sourdough bread with an organic acid (lactic

acid) [17]. Moreover, sodium proprionate but not lactic acid reduced gastric emptying rate

compared to control bread, which was paralleled by higher satiety scores. It is well-known that a

slower rate of gastric emptying is linked with increased perception of satiety [91, 92]. This

response may be further enhanced if indigestible carbohydrates are present in the food matrix

given that they are well-known to reduce FI and improve insulin sensitivity [93-96].

2.8.4 Sodium, Subjective Appetite and Food Intake

Limited research has been published on the direct effects of sodium consumption on SA and FI

in humans. An early study [18] in healthy adults examined the effects of salt (0 or 9.4 mg sodium

per kg body weight) added to a dairy-based meal comprised of 200 mL of water along with skim

milk and lactose (0.29 g/kg body weight of both ingredients). For perspective, a 70 kg adult

would have consumed 661 mg of sodium. Added-sodium resulted in increased hunger at 1.5, 2

and 2.5 h after ingestion compared to control, indicating that salt reduces post-meal satiety. In

another study by the same author, when participants were blinded to the taste of salt by ingesting

a tablet containing 393 mg of sodium with the dairy meal, it also increased hunger when

compared to placebo at all measured times. The increased hunger due to added sodium contrasts

that expected by the reported effects of salt on stomach emptying [90]. Delayed gastric emptying

19

is one important factor associated with increased perceived satiety [91, 92]. However, FI was not

explored to confirm the findings on satiety.

Other experimental studies have also failed to provide consistent evidence that salt promotes

energy intake. One study found that obese adolescents with insulin resistance have higher salt

recognition thresholds compared to lean controls [111], suggesting that excess adiposity may

induce gustatory changes that encourage overconsumption of high-sodium foods to elicit a salty

taste. Also, individuals habituated to a high level of dietary sodium intake are likely to choose

high-sodium foods [97]. On the other hand, sodium restriction has failed to promote weight loss

[98] or decrease FI [99] even though preference for salty foods decreases over time [98]. It has

also been recently hypothesized that salted food acts like a neural opiate agonist by generating a

hedonic “delicious” reward [100, 101], eventually leading to excess caloric intake and weight

gain.

Stronger evidence for an association between salt intake and FI is provided by studies showing

that sodium ingestion affects mechanisms regulating FI including gut peptides. For example, GIP

and GLP-1 stimulate the release of insulin prior to increases in postprandial glycaemia [102,

103] and are associated with reduced appetite [104, 105]. Plasma GIP levels increase more after

ingestion of drinks providing both sodium (1062 mg) and glucose (87 g) compared to glucose-

mannitol drinks [22]. GLP-1 is also involved in sodium and water homeostasis in both rats [106]

and obese [107] and normal weight [73] humans. It is hypothesised that a high-salt preload

stimulates the release of GLP-1 as water is ingested to quench thirst, acting as a gastrointestinal

signal to the brain to terminate rehydration even before information on plasma osmolality is sent

directly to the hypothalamus [73]. If ad libitum water and food are offered together at a later

meal following a salty snack, it is possible that FI may be reduced as WI diminishes. Further

supporting a benefit to high intake of sodium on FI are observations on ghrelin, which is secreted

by the stomach and rises gradually before a meal to initiate consumption [108]. Lower plasma

levels of active acylated ghrelin were observed in Caucasian men and women as well as African-

American men after four days of a high-sodium diet (5060 mg) compared to a normal-sodium

diet (1150 mg) [109]. Diets were matched for potassium and micronutrient content. Taken

20

together, these observations suggest that high sodium intake reduces ad libitum FI due to its

effects on GIP, GLP-1 and ghrelin.

Consistent with suggestions that low sodium intake may increase FI are studies in rats. Brain

regions involved in the regulation of FI also respond to hormones controlling sodium

homeostasis, namely ANGII and aldosterone. It is interesting to note that these hormones

increase during long-term sodium restriction and heighten the desire to ingest salt, otherwise

known as salt appetite [31, 72, 77, 110, 111]. Salt appetite may drive individuals to consume

high-sodium foods, thereby deriving a higher caloric intake. However, intracerebral injections of

ANG II in rats suppress FI through binding to its receptor [112] and increase expression of

uncoupling protein-1 mRNA [113], which is produced in brown adipose tissue and responsible

for increased energy expenditure [114]. Moreover, adult rats reduced FI even if given access to

ad libitum WI [113], indicating that FI decreased independently of simultaneous fluid intake.

Unfortunately, while the above findings suggest that increasing sodium intake both acutely and

chronically may potentially affect satiety and possibly FI, the short- and long-term effects are

contradictory.

2.9 Sodium Intake and Glycemic Control

It is widely believed that BG and insulin are linked with acute FI and SA. According to the

glucostatic theory, a spike in BG levels in the acute increases subjective feelings of fullness

while a dip promotes hunger [115]. It is theorized that these fluctuations are detected by the

central nervous system and translated into appetite-suppressive effects on the hypothalamus.

Similarly, postprandial insulin is strongly linked with decreased hunger and increased satiety in

normal but not overweight individuals [116]. Hyperglycemia may also increase fluid intake by

upsetting ECF osmolality. Cells normally take up glucose via insulin-mediated transport but are

unable to absorb glucose properly if they become unresponsive to insulin [67]. Hyperglycemia

may then increase plasma osmolality and contribute to intracellular thirst. However, it is unclear

if acute ingestion of sodium improves or worsens postprandial BG control, especially in

21

normoglycemic adult populations. Factors that may help explain divergent results are food

matrix (solid versus liquid form) and the presence or absence of carbohydrates.

2.9.1 Carbohydrates and Sodium Absorption

Sodium and glucose are absorbed together in the small intestine via secondary active symport

proteins like sodium-glucose transport proteins (SGLT1) located along the intestinal epithelia

[19-21]. Moreover, sugars in the intestinal lumen stimulate sodium absorption in the jejunum but

not the ileum [19], which is then quickly followed by fluid absorption due to osmosis [21]. The

coupling between these two nutrients and glucose‟s effect on salt and water uptake explain the

addition of glucose to oral rehydration solutions [21].

Although debated [23-25, 28], sodium can also increase glucose absorption [21] especially for

available carbohydrates. A study [22] investigating the effects of acute sodium intake on BG

response observed that a glucose solution containing 1061 mg sodium increased postprandial BG

concentrations compared to a glucose-mannitol2 drink of equal osmolarity. On the other hand,

indigestible carbohydrates like dietary fibre decrease glucose and sodium uptake. One study

found that sodium and glucose absorption were independently reduced following intestinal

perfusion of pectin [117]. Pectin is an insoluble fibre that increases the viscosity of the jejunal

unstirred water layer and delays nutrient absorption. However, sodium-glucose co-absorption

itself was not impaired.

2.9.2 Food Matrix Form, Sodium and Gastric Emptying

Although not fully investigated, glucose absorption and gastric emptying rate in response to

sodium content are likely influenced by the physical state of the food matrix; that is, solid or

liquid. Like liquids, a hypertonic solid food containing available sugars should theoretically

decrease glucose absorption compared to the same item without sodium. Moreover, a solid food

2 Mannitol is a non-permeable sugar alcohol approved for medicinal use as an osmotic diuretic and a mild renal

vasodilator. It is filtered by the glomeruli of the kidneys but is not reabsorbed from the renal tubule, leading to a

decrease in water and sodium reabsorption because of its osmotic properties.

22

empties more slowly than liquids, thereby further reducing glucose absorption. One study [118]

comparing solid foods and liquids with and without sodium found that macaroni led to lower

postprandial BG concentrations compared to a glucose solution irrespective of sodium content. It

may be that other factors known to influence gastric emptying, like energy density [119] and

macronutrient type [120], impinge on sodium‟s intestinal effects. For instance, it is possible that

differences in blood glucose responses would be observed if a solid food is given consisting of a

higher proportion of complex carbohydrates than rapidly digestible starches.

2.9.3 Acute Sodium Ingestion and Glycaemia

Based on the available studies in healthy weight individuals, it is unclear if sodium increases or

has no effect on postprandial glycaemia even though study protocols and sodium amounts

administered were comparable.

In healthy weight individuals, salt added to a glucose solution (1062 mg sodium + 87 g glucose)

increased postprandial BG and insulin concentrations between 45 to 105 min following ingestion

compared to an isomolar glucose drink containing 87 mmol mannitol [22]. However, glucose

disposal rates over 3 hours were comparable for both drinks, indicating that intestinal absorption

of glucose increased in the presence of sodium. Similar to BG response, the hormone GIP, which

slows gastric motility and induces the secretion of insulin, increased in plasma. Thus, sodium

enhanced intestinal glucose absorption and stimulated the release of GIP, which augmented

plasma insulin concentrations. In another similar study in healthy adults, 1672 mg sodium added

to cooked lentils and white bread each providing 50 g available carbohydrates led to higher

incremental BG AUCs than their unsalted versions [26]. These results suggest that satiety and FI

may have also been decreased but these outcomes were not measured.

Other studies indicate no relation between sodium in foods or beverages and BG. No effect of

sodium on glycaemia was found with the addition of 2360 mg sodium to a beverage (20%

glucose solution) or a solid meal (boiled macaroni) when each provided 50 g available

carbohydrates [118]. As would be expected, glucose solutions with or without added-sodium led

to higher peak plasma BG concentrations than both macaroni meals in healthy adults. However,

BG AUCs were not affected by sodium whether it was consumed in a beverage or solid meal. In

23

another trial, three meals providing 50 g available carbohydrates of varying glycemic indices

(mashed potatoes, rice, and lima beans) without or with 1678 mg added-sodium were again

consumed by healthy and normal-weight individuals [27]. Regardless of sodium content, mashed

potatoes led to the highest BG and insulin peaks at around 45 min; while beans led to low and

stable postprandial BG and insulin responses given their lower glycemic index. BG and insulin

incremental AUCs were also comparable for the control and added-sodium version for each

meal. A third study also found no differences between the glycemic responses over 180 min to a

glucose solution, boiled yam and boiled black-eyed peas preloads each providing 75 g available

carbohydrates without or with 1668 mg added-sodium in young, healthy Nigerian men [28].

Beans contained the most dietary fibre (4.8 g per 100 g dry weight) whereas the yam treatment

provided 0.9 g per 100 g raw weight and the glucose solution had none. However, the presence

of dietary fibre did not lead to statistically different results between treatments without or with

added-sodium as seen by Gans [118] and Slyper [27]. Regardless of sodium, mean peak plasma

glucose concentrations and AUCs were lowest for black-eyed beans and highest for glucose

although not statistically different.

One caveat is that the above studies explored the effect of only a single amount of added-sodium

in healthy populations. Nevertheless, one trial carried out in children (15 years old or below)

with stable type I diabetes observed no differences in BG concentrations over 180 min following

ingestion of a 75 g oral glucose solution without or with 1967 mg added-sodium [121]. Acute

trials investigating the role of conditions like obesity, insulin resistance, salt sensitivity and

intestinal disorders like celiac disease are still lacking, especially in adults.

2.9.4 Chronic Sodium Ingestion and Glycaemia

Longer-term studies in humans indicate that high sodium intake may initially improve but later

dysregulate glycemic control. In healthy lean adults, a high-sodium diet (4600 mg) for six days

significantly increased insulin-mediated glucose-uptake compared to a low-sodium (460 mg),

reflecting improved insulin sensitivity in healthy men and women [122]. In contrast, salt-

sensitive elderly volunteers developed insulin resistance after high-sodium intake for 13 weeks

24

even though they initially experienced improved insulin sensitivity compared to a low-sodium

diet [123].

Studies in rats support the negative effects of long-term high-sodium intake in humans. A high-

sodium diet (3.12%) fed for six weeks to salt-resistant rats enhanced adipocyte insulin sensitivity

for glucose uptake but increased fasting insulin levels and contributed to adipocyte hypertrophy

and increased mass of subcutaneous and periepididymal fat depots [124]. In another study, salt-

sensitive rats fed a high-sodium (8%) diet for four weeks presented lower glucose infusion and

utilization rates along with reduced insulin-mediated skeletal muscle glucose uptake compared to

those fed the normal diet [125].

2.9.5 Insulin Resistance, Obesity and Sodium Balance Dysregulation

Another possibility is that impaired glucose tolerance results from dysregulation of sodium

balance hormones independently of dietary sodium intake. Elevated angiotensin expression has

been observed in isolated human abdominal adipocytes treated with increasing concentrations of

insulin [126] and angiotensin II has been shown to promote lipogenesis in human adipose cells

[127]. Aldosterone is also abnormally elevated in overweight individuals [128] and is associated

with higher fasting insulin, C-peptide and HOMA values [129]. Aldosterone downplays insulin

signalling by decreasing insulin-receptor substrates (IRS-1 and IRS-2) expression and decreasing

phosphorylation in isolated adipocytes [130] and smooth muscle cells [131]. Sodium balance

hormones may be disturbed by obesity and in that manner impair insulin-mediated glucose

uptake.

Altogether, the available findings suggest that salt intake, insulin and adipose may be linked with

BG control. A self-feeding cycle may arise in which hyperinsulinemia stimulates visceral

adiposity to upset sodium balance. These endocrine disruptions may then aggravate insulin

resistance by impairing glucose uptake and increasing the number and size of adipocytes non-

responsive to insulin.

25

2.10 Summary

Sodium intakes at current levels are believed to play a direct role in the development of

hypertension and cardiovascular disease. In addition, its use in the food supply has been

associated with obesity and insulin resistance. Sodium and fluid intakes also correlate. However,

there are limited reports on the effects of sodium on subsequent FI and WI at a later meal; as

well as BG concentrations before and after a meal. Therefore, the objective of this thesis was to

describe the effects of adding graded amounts of sodium to a solid food (pulses) or liquid form

(tomato drink) on FI, WI and BG and on subjective feelings of appetite and thirst.

26

CHAPTER 3 RATIONALE, HYPOTHESIS AND OBJECTIVES

3 3.1 Rationale

Experimental studies in humans and animal models suggest that sodium may be a factor directly

affecting the regulation of subjective appetite, FI, and WI independently of taste. However, none

have explored the acute effects of sodium on ad libitum FI and WI at a later meal. The available

research on the effects of acute sodium intake on BG is conflicting, which may be due to the

choice of treatment vehicle and the amount of sodium tested. Thus, the following reports the

results of two clinical trials designed to elucidate the acute effects of a range of sodium added to

a solid or beverage on ad libitum FI and WI, SA and thirst ratings, and BG.

3.2 Overall Hypothesis

Higher sodium content of a food or beverage increases acute ad libitum FI and WI at a later

meal, as well as SA, thirst and BG concentrations before and after a meal in healthy young men.

3.3 Overall Objective

The primary objective was to investigate the effects of sodium content of solids and liquids on

acute FI regulation, SA and thirst, and BG in healthy young men.

3.3.1 Specific Objectives

Experiment 1: To investigate the acute effects of sodium content of a solid food (beans) on:

1. Ad libitum FI and WI at a meal provided 120 min later;

2. BG, SA and thirst over 120 min before the meal.

Experiment 2: To determine the acute effects of sodium content of a liquid (tomato beverage) on:

1. Ad libitum FI and WI at a meal served 30 min later;

2. BG, SA and thirst before (0 to 30 min) and after (60 to 180 min) a meal.

27

CHAPTER 4 MATERIALS AND METHODS

4 4.1 Subjects

Healthy, non-smoking males were recruited through advertisements placed around the University

of Toronto St. George Campus meeting the following criteria: aged 20 to 30 years of age and

with a normal weight body mass index (BMI) between 20 and 24.9 kg/m2 to comply with the

World Health Organization‟s standards for healthy BMI [132]. At the initial contact over the

phone or by e-mail, eligibility requirements were described to potential participants and they

were asked for their age, body weight, height, if they smoked, if they had any metabolic diseases

and if they were taking any medications. Breakfast skippers, smokers, dieters and individuals

with hypertension (140/90 mmHg) [133], diabetes (fasting BG > 7.0 mmol/L) [134] or other

metabolic diseases along with those taking medications were excluded. Individuals who fulfilled

the eligibility requirements were asked to come to the Department for a second screening (in-

person) to confirm their weight and height and have them complete the Baseline Information

Questionnaire, the Eating Habits Questionnaire Form and the Food Acceptability Questionnaire.

Individuals who regularly skipped breakfast and followed restrictive diets (determined from

achieving a score of 11 or higher on the Eating Habits Questionnaire) were excluded from the

study [135]. After this second screening session, qualified participants were asked to read over

and sign the consent form. Participants received monetary compensation for completing all

required sessions.

Both experiments received approval from the University of Toronto Health Sciences Research

Ethics Board. Participants were recruited separately for each study; however, two individuals

participated in both experiments after following a minimum one-month washout period. Sample

sizes were determined based on power analyses calculated for within-subject designs from

previous FI regulation studies investigating the effect of pulses on subjective appetite and FI in

young men [136]. In these studies, a sample size of 16 was estimated to be required to show a

treatment response on FI of 150 kcal with a power of 0.80 and α < 0.05.

28

For Experiment 1, initial recruitment began December 2007 and terminated in October 2008. In

all, sixteen subjects were recruited, signed the consent form and completed all required sessions.

No subjects withdrew from this study nor were there any statistical outliers for FI. For

Experiment 2, initial recruitment began June 2008 and terminated in May 2010. In all, 26

subjects were recruited and signed the consent form. Five subjects withdrew from the study

while actively participating due to: undisclosed reasons (1 participant); scheduling conflicts (2

participants); inability to fast the night before scheduled visits and consume a standardized

breakfast 4 hours before arrival (1 participant); and dislike of tomato beverage temperature (1

participant). In total, twenty-one eligible male participants completed this study. Two

participants were determined to be outliers because their FI and WI were less than 2 standard

deviations of the sample mean on 2 visits and were further eliminated, resulting in a final sample

size of 19 for this study.

4.2 Study Design

Two experiments were conducted in healthy young men following a within-subject, repeated-

measures design involving five weekly visits each. Treatments were provided single-blinded and

randomly with the use of a random sequence generator program available at www.random.org

[136]. Subjects served as their own control while random distribution eliminated participant bias.

All treatments were isocaloric, isovolumetric and of equal weight; preloads only differed in their

sodium content. For both studies, sodium was added as iodized table salt because it is the major

form of sodium consumed [2]. After treatments, FI and WI were measured at ad libitum pizza

meals; and BG, SA and thirst were measured regularly before (pre-meal) and after (post-meal)

the meals.

In Experiment 1, the test meal was provided 120 min after treatment consumption (135 min after

baseline) based on a previous study linking sodium content of canned pulses with higher

subjective thirst ratings over 120 min [137]. Subjects received three treatments in random order

containing white pea beans and tomato sauce without added-sodium (0 mg; control) or with 740

mg or 1480 mg of added-sodium. The lower amount of added-sodium was chosen to represent

the average sodium content of canned pulses used in the aforementioned pulse study [137]. The

http://www.random.org/

29

sodium amounts for the 300-kcal treatments as estimated from the labels were approximately:

804 mg in yellow split peas; 754 mg in chickpeas; 850 mg in lentils; and 836 mg in white pea

beans. Since the control treatment had about 71 mg of naturally occurring sodium, approximately

740 mg was added to match the average content of the previous study. This amount was then

doubled to 1480 mg to formulate a high added-sodium treatment. Because a high-sodium tomato

sauce was added to pulses in the previous study [137], a no-added-sodium tomato puree was

used in this experiment to maintain consistency between treatment compositions of these two

studies. To address the separate question of the effect of water ingestion prior to a meal on FI

and satiety, 150 and 500 mL of water were given 10 min before the test meal. Because these

treatments addressed a question independent of bean sodium content, these results were analyzed

separately and were not compared to the two added-sodium bean preloads. This latter component

of Experiment 1 is reported separately in Appendix I (8.1). In Experiment 2, FI and WI were

measured at a test meal given 30 min after baseline. Subjects received five treatments including

the low-sodium control and treatments with 500, 1000, 1500 and 2000 mg of added-sodium. The

range of sodium from 0 to 2000 mg in increments of 500 mg was added to a tomato beverage to

reflect the amounts found in commercially-available foods.

4.2.1 Experiment 1 Treatments

White pea beans were selected as the treatment vehicle for this study to provide a solid matrix

for sodium ingestion and because they are widely consumed in North America [136]. Also,

beans were cooked from their dry form to control the amount of salt added; and no-added

sodium tomato puree was used as in previous studies [137].

The treatment vehicle consisted of 250 kcal unsalted white pea beans (73.5 g dry Thompson‟s

White Pea Beans, Thompsons, Toronto, ON) and 50 kcal no-added-sodium tomato sauce (180

mL Hunt‟s Tomato Sauce No-Salt Added, Conagra Foods Canada Inc., Mississauga, ON).

Treatments differed in their sodium contents, with sodium having been added as iodized salt

(Sifto table salt; Sifto, Mississauga, Canada) as follows: 1) beans with tomato sauce (control; C);

2) control with 740 mg added-sodium (low-sodium; LS); and 3) control with 1480 mg added-

sodium (high-sodium; HS). The pre-meal water treatments were: 4) 150 mL (low pre-meal

30

water; LW); and 5) 500 mL (high pre-meal water; HW). Participants drank water 10 min before

consuming the control beans at baseline.

Nutrient composition of the pulse treatments is depicted in TABLE 4.1. The beans were cooked

using distilled water up to 2 days in advance in the experimental kitchen following Pulse

Canada‟s Guide to Cooking Pulses quick soak method [138]. First, beans were rinsed and

brought to a boil in a saucepan for 2 min (750 mL water for every 250 mL beans). They were

then removed from heat, covered and let sit for 1 hour. After, the soaking water was discarded

and beans were again brought to a boil with fresh water and covered tightly. Heat was reduced

and the beans were simmered until tender (45 to 60 min). After weighing out the individual

servings, the beans were refrigerated and micro-waved for 1 min 30 sec with tomato sauce on the

afternoon of the session. Beans were then prepared according to the assigned treatment (control,

low-sodium, or high-sodium). Subjects were given 150 mL of room-temperature bottled water to

drink immediately after they finished eating to minimize treatment aftertaste.

4.2.2 Experiment 2 Treatments

Participants received 5 tomato-based beverages with added-sodium (0 mg, 500 mg, 1000 mg,

1500 mg and 2000 mg). Nutrient composition of the beverages is depicted in TABLE 4.2.

Tomato juice was selected because it is a familiar food to Canadians and ranked third amongst

major grouped-food sources that contribute to total sodium intake (~8%) [38]. Higher sodium

amounts are also more hedonically acceptable when provided in a beverage with complex

flavours instead of water alone [36]. The incremental amounts of sodium chosen reflect the

amounts of sodium found in the top 20 foods that contribute to Canadians‟ daily sodium intake

[38]. The highest amount of sodium chosen (2000 mg) fell below the daily UL.

All tomato beverages (73 kcal) were prepared on-site 60 min before subjects‟ arrival and

consisted of 122.5 g no-sodium-added tomato paste (Hunt‟s Original Tomato Paste; ConAgra

Foods, Mississauga, Canada) and 238 mL bottled water (Canadian Springs; Mississauga,

Canada). Limited amounts of low-calorie flavouring ingredients were added to mimic

commercially-available tomato juice. These ingredients were: 2.5 mL lemon juice (ReaLemon

31

Lemon Juice; Cadbury Beverages Delaware Inc., Mississauga, Canada); 1.9 mL garlic herbs

(McCormick No Salt Added Garlic & Herb Seasoning; McCormick Canada, London, Canada);

0.6 mL Worcestershire sauce (Lea & Perrins Worcestershire Sauce; HJ Heinz Company of

Canada Ltd., North York, Canada); and 0.3 mL Tabasco sauce (McIlhenny Co. Tabasco Brand

Pepper Sauce; Avery Island, USA). Finally, sodium was added to treatments as iodized salt

(Sifto table salt; Sifto, Mississauga, Canada).

Beverages were served isovolumetric (340 ml) to be similar to the serving size of commercially-

available tomato or vegetable juice in North America. Also, beverages were isocaloric (73 kcal)

and contained sufficient tomato paste to provide the average caloric content of commercially-

available tomato or vegetable juice (68 kcal for 340 mL of V8®; 82 kcal for 340 mL of

Clamato®). However, total carbohydrate, sugar and fibre contents were higher than in brand-

name tomato-based beverages in order to match for calories. Beverages were served chilled at a

standard refrigeration temperature (5ºC) and provided with 100 ml bottled water (Canadian

Springs; Mississauga, Canada) to reduce aftertaste.

32

TABLE 4.1. Exp 1: Composition of treatments consisting of white beans with tomato sauce.

Per serving

Control Low-sodium High-sodium Low-

water1

High-

water1

Weight (g) 443 443 443 443 443

Total energy (kcal) 300 300 300 300 300

Fat (g) 0.7 0.7 0.7 0.7 0.7

Saturated fat (g) 0 0 0 0 0

Trans fat (g) 0 0 0 0 0

Cholesterol (mg) 0 0 0 0 0

Sodium (mg) 71 811 1551 71 71

Carbohydrates (g) 55 55 55 55 55

Sugars (g) 12 12 12 12 12

Fibre (g) 22 22 22 22 22

Protein (g)

20 20 20 20 20

Water served with

treatment (mL)2

150 150 150 150 150

Pre-meal water (mL)1

0 0 0 150 500

1 Participants ate control beans at baseline and drank water 10 min before the pizza test meal (pre-meal water).

These treatments were part of a second arm of this experiment to independently assess the effects of WI before a

meal (Appendix 8) from added-sodium content of a solid food (beans).

2 Beans (control; low-sodium; high-sodium) were served with 150 mL room-temperature bottled water.

TABLE 4.2. Exp 2: Composition of treatments consisting of a tomato-based beverage.

Per serving

Control

500 mg 1000 mg 1500 mg 2000 mg

Volume (mL) 340 340 340 340 340

Total energy (kcal) 73 73 73 73 73

Fat (g) 0 0 0 0 0

Saturated fat (g) 0 0 0 0 0

Trans fat (g) 0 0 0 0 0

Cholesterol (mg) 0 0 0 0 0

Sodium (mg) 62 562 1062 1562 2062

Carbohydrates (g) 14.5 14.5 14.5 14.5 14.5

Sugars (g) 11 11 11 11 11

Fibre (g) 3.5 3.5 3.5 3.5 3.5

Protein (g)

3.7 3.7 3.7 3.7 3.7

Water served with

treatment (mL)

100 100 100 100 100

33

4.3 Experimental Protocol

4.3.1 Screening and Baseline

During screening, each subject was given an outline of the study and instructed on taking finger

prick blood samples. They selected a convenient start time and day to commit to in order to keep

their visits consistent on a weekly basis for the study duration. The day before each visit,

subjects were instructed to refrain from alcohol and caffeine intake as well as any unusual

exercise and activity. They were also to keep to their typical exercise routine and consume a

similar dinner each evening before their sessions followed by a 10-12 h overnight fast.

The morning of their visits, subjects consumed a standardized breakfast (300 kcal) and arrived at

the laboratory 4 h later to start their sessions. Subjects chose a start time between 1200 and 1430

h for Experiment 1 and 1000 and1300 h for Experiment 2. The breakfast consisted of ready-to-

eat cereal (Honey Nut Cheerios; General Mills, Mississauga, Canada), 250 mL of 2% milk

(Sealtest; Markham, Canada), 238 mL of orange juice (Tropicana; Bradenton, Florida) and 500

mL bottled water (Canadian Springs; Mississauga, Ontario). Subjects were asked to immediately

consume breakfast upon waking up and to refrain from eating between breakfast and the start of

study sessions. However, they were allowed to drink the water provided to them up to 1 h before

arriving. Lastly, they were asked to use the same mode of transportation for each visit if feasible.

Upon arrival, subjects were seated in the examination room. To assess compliance and determine

changes over the preceding 24-hours that could have disturbed their present state, they were

asked to complete a “Sleep Habits and Stress Factors Questionnaire” (Appendix 8.11.1) and a

“Recent Food Intake and Activity Questionnaire” (Appendix 8.11.2). Visual Analogue Scales

(VAS) questionnaires measured their baseline (time 0 min) “Motivation to Eat” (Appendix

8.11.3) and “Physical Comfort” (Appendix 8.11.4) [139]. If they indicated major departures from

their daily routine such as illness or unusual stress, they were asked to reschedule.

Following completion of the VAS questionnaires, a baseline blood sample was taken. If initial

BG was > 5.6 mmol/L, a second reading was taken 5 min later; if BG remained elevated,

suggesting recent food or drink consumption, the participant was asked to reschedule [139].

Subjects remained seated throughout all experimental sessions and were allowed to read or listen

34

to music. FI testing and blood collection took place at the Department of Nutritional Sciences in

the Fitzgerald Building. Treatments and pizza were prepared in the laboratory kitchen.

4.3.2 Experimental Protocol

After baseline subjective information and BG were assessed, subjects proceeded to the feeding

room to consume the treatment. Subjects were asked to consume the solid food (beans) in 10 min

in Experiment 1 and drink the beverage (tomato juice) in 5 min in Experiment 2 at a constant

pace. Upon finishing, they completed a VAS palatability questionnaire at 15 min in Experiment

1 and 5 min in Experiment 2.

Additional VAS questionnaires were completed and BG measured in Experiment 1 at 30, 45, 60,

75, 105, and 135 minute after baseline except for physical comfort, which was only measured at

15, 75, and 135 min. In Experiment 2, BG was measured and VAS filled out at 15 and 30 min

after baseline (pre-meal) and again at 60, 75, 90, 105, 120, 150, and 180 min after baseline (post-

meal).

Subjects were given 20 min to consume an ad libitum pizza meal. The pizza meal was provided

135 min following the start of consumption of the treatments in Experiment 1 and at 30 min after

the start of drinking the treatments in Experiment 2. During the meal they were provided with

unlimited bottled spring water. After the pizza meal, subjects returned to the examination room

to complete the pizza palatability VAS followed by further post-meal VAS and BG

measurements.

4.4 Dependent Measures

4.4.1 Visual Analogue Scale (VAS) Questionnaires

VAS are 100 mm lines affixed with opposing descriptions at either end [96, 139, 140]. Subjects

mark an “X” on the line to depict their feelings at each time point. Scores are determined by

measuring the distance (mm) from the left starting point to the intersection of the “X.” In

Experiments 1 and 2, SA, thirst and physical comfort were measured whereas energy and fatigue

35

(tiredness) were assessed only in Experiment 2. Following the consumption of the treatments and

test meal in both studies, palatability was measured using VAS.

4.4.1.1 Subjective Appetite (SA)

The Motivation to Eat VAS questionnaire was used to measure SA [96, 139, 140] and consisted

of 4 standardized scales:

1. How strong is your desire to eat? (“Very weak” to “Very strong”);

2. How hungry do you feel? (“Not hungry at all” to “As hungry as I‟ve ever felt”);

3. How full do you feel? (“Not full at all” to “Very full”); and

4. How much food do you think you could eat? (“Nothing at all” to “A large amount”).

To assess treatment effects, the summary measure of average appetite was calculated for each

measurement time by averaging the 4 questions presented for statistical analysis as follows:

appetite score = [desire to eat + hunger + (100 – fullness) + prospective consumption]/4 [96,

139-141]. In addition, each individual question was analyzed for treatment effects.

4.4.1.2 Subjective Thirst

Subjective thirst was assessed after SA using the following question:

5. How thirsty do you feel? (“Not thirsty at all” to “As thirsty as I have ever felt”).

4.4.1.3 Physical Comfort

The Physical Comfort VAS was used to assess each participant‟s well-being during sessions and

included questions to survey for side-effects associated with high-fibre foods [142]:

1. Do you feel nauseous? (“Not at all” to “Very much”);

2. Does your stomach hurt? (“Not at all” to “Very much”);

3. How well do you feel? (“Not well at all” to “Very well”);

4. Do you feel like you have gas? (“Not at all” to “Very much”); and

36

5. Do you feel like you have diarrhoea? (“Not at all” to “Very much”)

As with SA, the summary measure of average physical comfort was calculated to assess the

treatment effects on well-being. The questions were averaged for each time point and statistically

analyzed as follows: physical comfort score = [(100 – nausea) + (100 – stomach pain) + well-

being + (100 – flatulence) + (100 – diarrhoea)]/5. In addition, each individual question was

analyzed for treatment effects.

4.4.1.4 Subjective Palatability

For Experiment 1, treatment and test meal palatability were rated by the following [143]:

1. How pleasant have you found the beverage/food? (“Not at all pleasant” to “Very

pleasant”).

For Experiment 2, treatment and test meal palatability were rated by the following [143]:

1. How pleasant have you found the beverage/food? (“Not at all pleasant” to “Very

pleasant”);

2. How tasty have you found the beverage/food? (“Not at all tasty” to “Very tasty”); and

3. How did you like the texture of the beverage/food? (“Not at all” to “Very much”).

Average palatability was calculated by averaging ratings for pleasantness, tastiness and texture.

4.4.2 Blood Glucose Concentrations

Capillary blood glucose concentrations were measured as previously described [96, 136, 139,

140]. Subjects first swabbed their finger with an antiseptic isopropyl alcohol pad and pricked

themselves using a sterilized monojector lancet device (Sherwood Medical; St. Louis, USA).

Subjects were instructed to puncture their fingers or thumbs on the sides of the digit parallel to

the side edges of the nail and to not use the tip or pad of the finger to minimize pain. The first

drop of blood was wiped off because of contamination with interstitial fluid and alcohol. A

second drop flowing freely from the clean, dry puncture site was placed on an Accu-Chek test

37

strip for immediate reading with a glucose monitor (Accu-Chek Compact and Compact-Plus;

Roche Diagnostics Canada, Laval, Canada). Each subject was assigned the same glucometer for

each visit to reduce within-subject variation. The monitors and test strips were standardized

against commercial human serum at 2 glucose concentrations of 6.3 and 10.0 mmol/L (Assayed

Human Multi-sera; Randox Laboratories LTD, Mississauga, Canada).

4.4.3 Test Meal

Subjects were allowed up to 20 min to eat pizza and instructed to eat until comfortably full. The

meal consisted of three 5” diameter pizza varieties given in excess (McCain Deep „N Delicious;

McCain Foods Canada, Florenceville, Canada) with unlimited bottled water (Canadian Springs;

Mississauga, Canada). During screening, subjects ranked the pizza varieties (Deluxe, Pepperoni,

and Three-Cheese) in order of their preference in order to provide them with four pizzas per tray

at all sessions, two pizzas of their first choice and one pizza of their second and third choices.

On average, the pizzas provided 10.0 g protein, 7.6 g fat, 26.6 g carbohydrates, 500 mg sodium

and 226 kcal/100 g. These pizzas lack an outer crust resulting in uniform energy content and

eliminated the chance that subjects would eat only the energy-dense filling and leave the outside

crust. The pizzas were stored frozen, cooked according to the manufacturer‟s directions (baked

for 8 min at 430°C and cut into quarters), weighed before serving and placed on a tray. Bottled

water was also weighed before serving and kept refrigerated at 5ºC. Subjects were served a fresh

tray of pizzas every 6 to 7 min until they announced they were full and declined further trays.

After termination of the test meal, leftover food and bottled water were weighed in order to

calculate the weight (in grams) of pizza and water consumed based on the compositional

information provided by the manufacturer.

4.5 Data Analysis

SAS version 9.2 (Statistical Analysis Systems, SAS Institute, Carey, NC) was used for statistical

analysis.

38

PROC mixed two-way repeated measures analysis of variance (ANOVA) was applied to

determine the effects of treatments, time and time-by-treatment interactions on outcome

variables measured over the study period, including absolute and change from baseline values

for appetite and thirst ratings and BG concentrations. When a treatment-by-time interaction was

statistically significant, a PROC MIXED one-factor ANOVA was followed by Tukey-Kramer

post hoc test to investigate the effect of treatment on absolute and changes from baseline for BG,

appetite and thirst at each time of measurement. Pre-meal changes from baseline were calculated

from 0 min (immediately before treatment consumption) in both studies and post-meal changes

from 30 min (immediately before test meal consumption) for Experiment 2.

The effect of treatment on FI, sodium intake and WI at the meal and net incremental area under

the curves (AUC) for appetite, thirst and BG were also determined by one-way ANOVA

followed by Tukey-Kramer post hoc test to declare mean differences. Net AUCs for BG and

VAS subjective measures were calculated from 0 to 135 min (cumulative) for Experiment 1; and

0 to 30 min (pre-meal), 30 to 180 min (post-meal) and 0 to 180 min (cumulative) for Experiment

2. Net AUCs were determined by applying the trapezoid rule, which is calculated by subtracting

the area below baseline levels (negative increment) from the area above (positive increment) [35,

136, 139, 140].

For Experiment 1, comparisons between added-sodium treatments to control and pre-meal water

treatments to control were planned in advance (i.e. a priori comparisons) [144]. Although

subjects received the five treatments in random order, the effects of sodium addition and water

consumption prior to the meal were examined independently. For the purpose of the primary

objective of this thesis, only the results of the sodium treatments are included in the body of this

thesis. The effects of the pre-meal WI are reported in Appendix I. Thus, orthogonal contrasts

were used to determine the independent effects of added-sodium and pre-meal WI to no-added

sodium bean preloads on all dependent measures. The contrasts between added-sodium beans

and control were: 1) 0 mg vs. 740 mg; 2) 0 mg vs. 1480 mg; and 3) 740 mg vs. 1480 mg. Data

for all five preload conditions were used to estimate the pooled variance for determining

significance of treatments.

39

All results are presented as mean ± standard error of the mean (SEM). The statistical significance

was concluded with the P-value less than 0.05.

40

CHAPTER 5 RESULTS

Results for both studies are presented together. In Experiment 1, beans with 740 mg and 1480

mg of added-sodium are referred to as low-sodium (LS) and high-sodium (HS) beans,

respectively.

5 5.1 Subject Characteristics

In Experiment 1, men (n = 16) had a mean (± SEM) body weight of 71.6 ± 1.3 kg, height of 1.80

± 0.01 m, BMI of 22.2 ± 0.4 kg/m2 and average age of 21.5 ± 0.4 y (TABLE 5.1). Similarly in

Experiment 2, men (n = 19) who were 22.9 ± 0.6 y on average participated with a mean body

weight of 73.6 ± 1.5 kg, height of 1.79 ± 0.01 m and BMI of 23.2 ± 0.3 kg/m2 (TABLE 5.2).

41

TABLE 5.1. Exp 1: Subject characteristics.

Subject No.

Age (y) Weight (kg) Height (m) BMI1 (kg/m²)

1 20 64.7 1.78 20.4

2 20 69.6 1.83 20.8

3 21 70.9 1.81 21.6

4 25 70.0 1.82 21.1

5 22 72.9 1.74 24.1

6 23 72.7 1.74 24.0

7 21 58.8 1.71 20.1

8 21 79.7 1.91 21.8

9 23 77.5 1.77 24.7

10 20 75.5 1.87 21.6

11 22 72.5 1.80 22.4

12 22 77.5 1.79 24.2

13 21 75.1 1.81 22.9

14 21 67.1 1.77 21.4

15 23 71.0 1.84 21.0

16 19 70.5 1.78 22.3

Mean 21.5 71.6 1.80 22.2

SEM2

0.4 1.3 0.01 0.4

1 BMI = Body Mass Index (kg/m

2)

2 SEM = Standard Error of the Mean, n = 16

42

TABLE 5.2. Exp 2: Subject characteristics.

Subject No.

Age (y) Weight (kg) Height (m) BMI1 (kg/m²)

1 20 75.0 1.83 22.4

2 21 58.0 1.71 19.8

3 23 79.0 1.88 22.4

4 20 77.8 1.79 24.3

5 28 79.3 1.78 25.0

6 21 69.9 1.81 21.3

7 27 76.9 1.85 22.5

8 20 68.9 1.67 24.7

9 30 71.7 1.76 23.1

10 25 75.2 1.79 23.5

11 23 89.2 1.93 23.9

12 21 66.0 1.72 22.3

13 21 76.0 1.75 24.8

14 21 77.2 1.76 24.9

15 23 72.1 1.82 21.8

16 22 75.1 1.77 24.0

17 23 71.4 1.83 21.3

18 23 72.5 1.79 22.6

19 23 68.0 1.84 20.1

Mean 22.9 73.6 1.79 23.2

SEM2

0.6 1.5 0.01 0.3

1 BMI = Body Mass Index (kg/m

2)

2 SEM = Standard Error of the Mean, n = 19

43

5.2 Treatment and Test Meal Palatability

5.2.1 Treatment Palatability Ratings

For Experiment 1, participants tended to rate control beans less pleasant to eat than high-sodium

beans (P = 0.06) (TABLE 5.3).

For Experiment 2, tomato beverage pleasantness and texture enjoyment were comparable for all

treatments (P = 0.16 and P = 0.36, respectively) (TABLE 5.4). However, tastiness ratings were

lower for 0 mg added-sodium than 500 and 1000 mg added-sodium (P = 0.02). After averaging

pleasantness, tastiness and texture ratings, palatability was not significantly affected by sodium

content (P = 0.07) although the trend was to lower ratings for control.

5.2.2 Test Meal Palatability Ratings

The ad libitum pizza meal was rated pleasant regardless of treatment sodium content in both

Experiment 1 (P = 0.48) and Experiment 2 (P = 0.36) (TABLE 5.3 and TABLE 5.4,

respectively).

44

TABLE 5.3. Exp 1: Effect of sodium content of a solid food (beans) on treatment and test meal

palatability1

Treatment added-sodium content Treatment pleasantness Test meal pleasantness

mm mm

C (0 mg) 38.0 ± 5.9 64.0 ± 6.2

LS (740 mg) 48.0 ± 6.0 66.1 ± 4.6

HS (1480 mg) 50.6 ± 6.5 64.6 ± 5.0

P2 0.29 0.48

1 All values are means ± SEM; n = 16. Values in the same column with different superscript letters are significantly

different, P < 0.05 (one-factor ANOVA for treatment effect followed by orthogonal contrasts).

2 Overall P value reflects data for all five preload conditions. Orthogonal contrasts were applied to compare control

and added-sodium treatments only. Treatment pleasantness: C vs. LS (P = 0.16); C vs. HS (P = 0.06); LS vs. HS (P

= 0.62). Test meal pleasantness: C vs. LS (P = 0.57); C vs. HS (P = 0.92); LS vs. HS (P = 0.63).

TABLE 5.4. Exp 2: Effect of sodium content of a beverage (tomato juice) on treatment and test

meal palatability1

Treatment palatability

Test meal

Pleasantness

Treatment

added-sodium

content

Pleasantness

Tastiness Texture

Average

palatability

mm mm mm mm mm

0 mg 41.9 ± 5.2 36.6 ± 5.1b 45.3 ± 5.3 41.3 ± 4.9 77.3 ± 3.7

500 mg 51.6 ± 5.7 53.1 ± 5.2a 51.7 ± 4.9 52.1 ± 5.0 77.5 ± 3.5

1000 mg 54.6 ± 5.1 55.7 ± 6.1a 53.6 ± 5.8 54.6 ± 5.3 74.2 ± 3.7

1500 mg 45.6 ± 6.1 49.9 ± 6.5ab

48.9 ± 5.3 48.2 ± 5.5 76.7 ± 3.4

2000 mg 46.9 ± 5.7 48.8 ± 6.1ab

52.6 ± 5.1 49.5 ± 5.1 74.3 ± 3.5

P 0.16 0.02 0.36 0.07 0.36


different, P < 0.05 (one-factor ANOVA for treatment effect followed by Tukey‟s post-hoc test).

45

5.3 Food, Sodium and Water Intakes

5.3.1 Food Intake

In Experiment 1, FI was approximately 116 kcal higher 120 min following consumption of low-

sodium beans compared with high-sodium beans (P = 0.05) (TABLE 5.5). FI consumed after

control beans was intermediate.

In Experiment 2, FI at the test meal given at 30 min after baseline was not affected by treatment

sodium content (P = 0.92) (TABLE 5.6).

5.3.2 Sodium Intake

In Experiment 1, sodium intake at the pizza meal paralleled energy intake and tended to be

approximately 263 mg higher after consumption of low-sodium beans compared with high-

sodium beans (P = 0.06) (TABLE 5.5). Sodium intake for control beans was intermediate.

Cumulative sodium intake increased as treatment sodium content increased (P < 0.0001).

In Experiment 2, sodium intake at the test meal was not affected by treatment sodium content (P

= 0.88) (TABLE 5.6). However, cumulative sodium intake increased with higher treatment

sodium content (P < 0.0001).

5.3.3 Water Intake

In Experiment 1, subjects drank similar amounts of water at the pizza meal (TABLE 5.5).

In Experiment 2, individuals drank more water following the beverage with 2000 mg added-

sodium compared with 500 mg added-sodium (P = 0.03) (TABLE 5.6). WI amounts for 0, 1000

and 1500 mg added-sodium were intermediate.

46

TABLE 5.5. Exp 1: Effect of sodium content of a solid food (beans) on food, sodium and water intakes1

Treatment added-sodium content Energy intake at test meal Sodium intake

Water intake at test meal Test meal Cumulative

2

kcal mg mg g

C (0 mg) 1337 ± 106ab

3072 ± 258 3143 ± 258c 352 ± 33

LS (740 mg) 1420 ± 114a 3257 ± 275 4068 ± 274

b 338 ± 36

HS (1480 mg) 1304 ± 81b 2994 ± 200 4545 ± 200

a 343 ± 34

P3 0.01 0.009 < 0.0001 0.0002

1 All values are means ± SEM; n = 16. Values in the same column with different superscript letters are significantly different, P < 0.05 (one-factor ANOVA for

treatment effect followed by orthogonal contrasts).

2 Sum of total treatment and test meal sodium contents.

3 Overall P value reflects data for all five preload conditions. Orthogonal contrasts were applied to compare control and added-sodium treatments only. Energy intake:

C vs. LS (P = 0.17); C vs. HS (P = 0.55); LS vs. HS (P = 0.05). Sodium intake: C vs. LS (P = 0.17); C vs. HS (P = 0.57); LS vs. HS (P = 0.06). Cumulative sodium

intake: C vs. LS (P < 0.0001); C vs. HS (P < 0.0001); LS vs. HS (P = 0.0007). Water intake: C vs. LS (P = 0.75); C vs. HS (P = 0.91); LS vs. HS (P = 0.67).

TABLE 5.6. Exp 2: Effect of sodium content of a beverage (tomato juice) on food, sodium and water intakes1

Treatment added-sodium content Energy intake at test meal Sodium intake

Water intake at test meal Test meal Cumulative

2

kcal mg mg g

0 mg 1313 ± 69 3012 ± 165 3074 ± 165e 337 ± 34

ab

500 mg 1265 ± 83 2893 ± 188 3455 ± 188d 320 ± 39

b

1000 mg 1231 ± 74 2820 ± 167 3882 ± 167c 389 ± 34

ab

1500 mg 1257 ± 75 2871 ± 172 4433 ± 172b 387 ± 31

ab

2000 mg 1249 ± 76 2857 ± 176 4919 ± 176a 397 ± 31

a

P 0.92 0.88 < 0.0001 0.03

1 All values are means ± SEM; n = 19. Values in the same column with different superscript letters are significantly different, P < 0.05 (one-factor ANOVA for

treatment effect followed by Tukey‟s post-hoc test).


47

5.4 Subjective Average Appetite

5.4.1 Absolute Average Appetite Scores

In Experiment 1, average appetite (0 – 135 min) was affected by time (P < 0.0001) and treatment

(P = 0.01) but no time-by-treatment interaction was observed (P = 0.11) (TABLE 5.7).

Explaining the effect of time, average appetite scores were highest at baseline (68.7 ± 1.8 mm) but

were reduced the most at 15 min (42.5 ± 2.2 mm) after treatment consumption, and gradually

increased near baseline levels by 135 min (65.1 ± 2.0 mm). Low-sodium beans led to a higher

average appetite marginal mean over time (58.9 ± 1.6 mm), indicating less appetite suppression,

compared with either control (54.2 ± 1.8 mm) or high-sodium beans (52.6 ± 1.8 mm) (P = 0.01

and P = 0.001, respectively). Of special note is that on average, subjects arrived at baseline (0

min) with lower average appetite scores prior to receiving high-sodium versus control (P = 0.02)

and low-sodium beans (P = 0.0006) despite treatment randomization. These differences were

likely due to the large range and variance in responses before consumption of high-sodium beans

(68.5 mm range and 18.1 mm standard deviation) in contrast to control (56.5 mm range and 15.1

mm standard deviation) and low-sodium beans (48.3 mm range and 14.3 mm standard deviation).

There were some extreme observations for two subjects that were two standard deviations or more

from the group mean for average appetite at 0 min (35.8 mm before control; and 26.5 mm before

high-sodium beans). Upon analysing the individual motivation-to-eat VAS (Appendix 8.2) and

graphing box plots (data not shown), these two subjects reported baseline ratings for desire to eat,

hunger and prospective food intake that were lower than the group means for high-sodium beans.

When the analysis was repeated excluding the average appetite data of these two outliers, the

differences at baseline remained between control and high-sodium beans (P = 0.05) and low- and

high-sodium beans (P = 0.003). Furthermore, mean average appetite across all time points was

still higher for low- versus high-sodium beans (P = 0.003) but not control (P = 0.19).

In Experiment 2, pre-meal appetite (0 – 30 min) was affected by time (P < 0.0001) but not

treatment (P = 0.89); no time-by-treatment interaction was observed (P = 0.89) (TABLE 5.8).

Average appetite scores were reduced from baseline (73.3 ± 1.9 mm) at 15 min after consumption

of the treatments (65.5 ± 1.8 mm), increasing thereafter at 30 min (71.4 ± 1.7 mm). Similarly,

post-meal appetite (60 – 180 min) was affected by time (P < 0.0001) but not treatment (P = 0.10)

48

nor was there a time-by-treatment interaction (P = 0.72). Post-meal average appetite scores were

the lowest immediately after the meal at 60 min (15.5 ± 1.3 mm), and gradually increased by 180

min by an average of 18.6 mm for all treatments.

5.4.2 Change from Baseline Average Appetite Scores

In Experiment 1, change from baseline appetite scores were affected by time (P < 0.0001) and

treatment (P = 0.0006) but no time-by-treatment was detected (P = 0.48) (TABLE 5.7). When

analyzed as the difference from baseline, average appetite was suppressed the most at 15 min by

an average of -26.1 ± 2.5 mm for all treatments; and gradually recovered near baseline levels by

135 min (-3.6 ± 1.8 mm). Average appetite marginal means for control, low-sodium and high-

sodium beans were similar; the treatment effect resulted from differences between control and the

pre-meal water treatments (8.1.6.3 Absolute Average Appetite Scores).

In Experiment 2, pre-meal change from baseline average appetite scores were affected by time (P

< 0.0001) but not treatment (P = 0.86) and time-by-treatment (P = 0.55). Over the 30-min period

before the test meal, average appetite scores were suppressed from baseline more at 15 min (-7.7

± 1.5 mm) than at 30 min (-1.9 ± 1.4 mm) for all treatments. Following the test meal, average

appetite changed over time (P < 0.0001) and was affected by treatment (P = 0.01) (TABLE 5.8).

However, no significant time-by-treatment interaction was observed (P = 1.00). Immediately after

the meal (60 min), subjects experienced an average reduction in appetite scores of 55.8 ± 2.5 mm

from right before they consumed the meal at 30 min. This was followed by an average increase of

13.7 mm at 180 min (-37.3 ± 2.7 mm) for all treatments. Over the post-meal period, 500 mg of

added-sodium resulted in a greater reduction in average appetite than control (-48.9 ± 2.2 mm

versus -42.9 ± 2.5 mm, respectively). Scores were intermediate for 1000 mg (-44.7 ± 2.2 mm),

1500 mg (-45.9 ± 2.2 mm) and 2000 mg (-45.2 ± 2.1 mm) of added-sodium.

5.4.3 Average Appetite AUC

Average appetite net AUC was not affected by treatment added-sodium content in either

Experiment 1 (TABLE 5.9) or Experiment 2 (TABLE 5.10).

49

TABLE 5.7. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal average appetite

scores at each measurement time1

Treatment added-sodium content Time marginal mean

Time C (0 mg) LS (740 mg) HS (1480 mg)

mm

Absolute ratings2

0 min 67.7 ± 3.8 69.3 ± 3.6 63.5 ± 4.5 68.7 ± 1.8a

15 min 38.9 ± 4.8 50.3 ± 4.2 41.9 ± 4.9 42.5 ± 2.2d

30 min 44.1 ± 4.6 51.2 ± 5.2 43.4 ± 5.1 45.3 ± 2.3d

45 min 48.4 ± 4.8 51.9 ± 4.6 46.5 ± 4.7 48.8 ± 2.1cd

60 min 51.8 ± 4.6 57.2 ± 4.7 48.2 ± 4.8 51.3 ± 2.1cd

75 min 56.0 ± 4.6 58.8 ± 3.6 53.6 ± 4.8 55.3 ± 2.0bc

105 min 61.2 ± 4.9 62.6 ± 2.9 59.7 ± 4.7 60.4 ± 2.0b

135 min 65.3 ± 5.4 69.8 ± 3.7 64.3 ± 4.5 65.1 ± 2.0ab

Treatment marginal mean 54.2 ± 1.8b 58.9 ± 1.6

a 52.6 ± 1.8

b --

Change from 0 min ratings3

15 min -29.3 ± 5.5 -19.0 ± 5.1 -21.6 ± 5.3 -26.1 ± 2.5e

30 min -23.6 ± 4.7 -18.0 ± 5.2 -20.1 ± 4.7 -23.4 ± 2.2de

45 min -19.2 ± 4.6 -17.4 ± 4.1 -17.0 ± 4.3 -19.9 ± 1.9cde

60 min -15.9 ± 4.8 -12.1 ± 3.7 -15.3 ± 4.2 -17.3 ± 1.9bcd

75 min -11.7 ± 4.3 -10.5 ± 2.7 -9.9 ± 4.1 -13.4 ± 1.8bc

105 min -6.5 ± 4.0 -6.7 ± 2.7 -3.8 ± 4.0 -8.3 ± 1.7ab

135 min -2.3 ± 5.2 0.5 ± 2.8 0.8 ± 4.0 -3.6 ± 1.8a

Treatment marginal mean -15.4 ± 1.9 -11.9 ± 1.6 -12.4 ± 1.8 --

1 All values are means ± SEM; n = 16. Values with different superscript letters are significantly different, P < 0.05

(one-factor ANOVA for treatment effect followed by orthogonal contrasts).

2 Absolute two-factor ANOVA. Time (P < 0.0001), treatment (P = 0.01) and time x treatment (P = 0.11). Treatment

effect: C vs. LS (P = 0.01); C vs. HS (P = 0.53); LS vs. HS (P = 0.001).

3 Change from baseline two-factor ANOVA. Time (P < 0.0001), treatment (P = 0.0006) and time x treatment (P =

0.48). Treatment effect: C vs. LS (P = 0.19); C vs. HS (P = 0.35); LS vs. HS (P = 0.70).

50


average appetite scores1

Treatment added-sodium content

Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm

Absolute pre-meal ratings2

0 min 73.1 ± 4.5 73.8 ± 4.2 72.1 ± 4.5 72.5 ± 4.9 74.8 ± 3.7 73.3 ± 1.9a

15 min 63.4 ± 4.7 66.8 ± 4.3 66.1 ± 3.3 66.0 ± 3.8 65.3 ± 3.9 65.5 ± 1.8b

30 min 69.0 ± 4.9 74.2 ± 3.7 69.1 ± 3.7 72.7 ± 3.8 71.9 ± 3.2 71.4 ± 1.7a

Treatment

marginal mean 68.5 ± 2.7 71.6 ± 2.3 69.1 ± 2.2 70.4 ± 2.4 70.7 ± 2.1 --

Absolute post-meal ratings2

60 min 15.1 ± 2.5 14.4 ± 2.8 17.1 ± 3.6 15.8 ± 2.9 15.3 ± 2.7 15.5 ± 1.3e

75 min 19.9 ± 3.9 18.1 ± 2.8 19.6 ± 3.6 22.1 ± 3.8 21.9 ± 3.1 20.3 ± 1.5de

90 min 24.8 ± 4.1 25.2 ± 4.3 22.9 ± 3.8 27.9 ± 4.5 24.9 ± 3.5 25.1 ± 1.8bc

105 min 26.6 ± 4.2 24.4 ± 3.8 24.1 ± 3.6 26.5 ± 3.8 27.5 ± 3.8 25.8 ± 1.7cd

120 min 29.1 ± 4.2 26.8 ± 3.7 25.8 ± 3.4 28.0 ± 4.2 29.8 ± 4.2 27.9 ± 1.7bc

150 min 32.1 ± 4.5 33.8 ± 4.6 29.4 ± 3.8 32.9 ± 4.6 32.3 ± 4.1 32.1 ± 1.9ab

180 min 34.8 ± 4.7 34.5 ± 5.0 31.2 ± 4.0 34.6 ± 4.5 35.2 ± 4.6 34.1 ± 2.0a

Treatment

marginal mean 26.1 ± 1.6 25.3 ± 1.6 24.3 ± 1.4 26.8 ± 1.6 26.7 ± 1.5 --

Change from 0 min pre-meal ratings3

15 min -9.7 ± 3.7 -7.0 ± 3.6 -6.1 ± 3.0 -6.5 ± 3.2 -9.5 ± 3.6 -7.7 ± 1.5b

30 min -4.1 ± 3.7 0.4 ± 3.4 -3.1 ± 2.8 0.2 ± 3.0 -3.0 ± 2.4 -1.9 ± 1.4a

Treatment

marginal mean -6.9 ± 2.6 -3.3 ± 2.5 -4.6 ± 2.0 -3.1 ± 2.2 -6.2 ± 2.2 --

Change from 30 min post-meal ratings3

60 min -53.9 ± 6.0 -59.8 ± 5.5 -52.0 ± 6.1 -56.9 ± 5.4 -56.5 ± 5.0 -55.8 ± 2.5e

75 min -49.1 ± 6.6 -56.1 ± 5.2 -49.4 ± 6.2 -50.6 ± 6.3 -50.0 ± 5.1 -51.0 ± 2.6de

90 min -44.2 ± 7.0 -49.0 ± 6.1 -46.2 ± 6.0 -44.8 ± 6.3 -46.9 ± 5.3 -46.2 ± 2.7cd

105 min -42.4 ± 6.5 -49.8 ± 5.7 -44.9 ± 5.9 -46.3 ± 5.6 -44.3 ± 5.4 -45.5 ± 2.6cd

120 min -39.9 ± 6.8 -47.4 ± 5.4 -43.3 ± 5.6 -44.8 ± 6.0 -42.1 ± 5.9 -43.5 ± 2.6bc

150 min -36.9 ± 6.7 -40.4 ± 5.9 -39.6 ± 5.6 -39.8 ± 5.9 -39.6 ± 5.7 -39.3 ± 2.6ab

180 min -34.2 ± 6.8 -39.7 ± 6.0 -37.8 ± 5.7 -38.1 ± 5.8 -36.6 ± 6.1 -37.3 ± 2.7a

Treatment

marginal mean -42.9 ± 2.5a -48.9 ± 2.2b -44.7 ± 2.2ab -45.9 ± 2.2ab -45.2 ± 2.1ab --

1All values are means ± SEM; n = 19. Values with different superscript letters are significantly different, P < 0.05

(one-factor ANOVA for treatment effect and Tukey‟s post-hoc test).

2 Absolute two-factor ANOVA. Pre-meal: time (P < 0.0001), treatment (P = 0.89) and time x treatment (P = 0.89).

Post-meal: time (P < 0.0001), treatment (P = 0.10) and time x treatment (P = 0.72).

3 Change from baseline two-factor ANOVA. Pre-meal: time (P < 0.0001), treatment (P = 0.86) and time x treatment

(P = 0.55). Post-meal: time (P < 0.0001), treatment (P = 0.01) and time x treatment (P = 1.00).

51


appetite areas under the curve (AUC)1

Added-sodium treatment content Pre-meal average appetite AUC2

mmmin

C (0 mg) -1803.1 ± 512.6

LS (740 mg) -1425.2 ± 388.0

HS (1480 mg) -1434.4 ± 478.0

P3 0.04



2 Pre-meal: 0-135 min.


and added-sodium treatments only. Average appetite AUC: C vs. LS (P = 0.48); C vs. HS (P = 0.73); LS vs. HS (P =

0.71).


meal and cumulative average appetite areas under the curve (AUC)1

Added-sodium

treatment content

Average appetite AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg -176.3 ± 80.1 -5691.7 ± 868.2 -6444.1 ± 871.8

500 mg -101.3 ± 75.0 -6505.0 ± 722.0 -6540.4 ± 920.9

1000 mg -113.7 ± 64.6 -5870.4 ± 768.5 -6336.6 ± 764.6

1500 mg -95.1 ± 64.8 -6130.5 ± 751.1 -6196.6 ± 944.3

2000 mg -165.0 ± 68.0 -6002.2 ± 711.3 -6592.3 ± 755.7

P 0.94 0.59 0.99



2 Pre-meal: 0-30 min; post-meal: 30-180 min; cumulative: 0-180 min.

52

5.5 Subjective Thirst

5.5.1 Absolute Thirst Ratings

In Experiment 1, absolute thirst ratings from 0 to 135 min changed over time (P = 0.006) but

were not affected by treatment (P = 0.45) (TABLE 5.11). Explaining the effect of time, thirst

was higher at 0 min (50.6 ± 2.3 mm) and 105 min (50.0 ± 2.3 mm) than at 15 min (42.2 ± 2.7

mm); and higher at 105 min than at 135 min (44.1 ± 2.6 mm). Also, subjects arrived at baseline

(0 min) with higher thirst ratings prior to receiving control versus high-sodium beans (P = 0.04).

As with average appetite at 0 min, there was a large range and variance in responses before

consumption of control (74.0 mm range and 21.1 mm standard deviation), low-sodium beans

(71.0 mm range and 19.9 mm standard deviation) and high-sodium beans (69.0 mm range and

22.9 mm standard deviation). There was a total of three extremely low observations from three

different subjects that were two standard deviations or more from the group mean prior to

consumption of control (10 and 14 mm) and low-sodium beans (11 mm). When the analysis was

repeated excluding the data for these three subjects, differences at baseline were present between

control and low-sodium beans (P = 0.01) and control and high-sodium beans (P = 0.01).

Furthermore, mean average appetite across all time points were not different (C vs. Ls, P = 0.95;

C vs. HS, P = 0.12; LS vs. HS, P = 0.10).

In Experiment 2, time (P = 0.03) but not treatment (P = 0.87) affected pre-meal thirst ratings and

no time-by-treatment interaction was observed (P = 0.80) (TABLE 5.12). Before the test meal,

participants felt thirstier at 0 min (58.8 ± 2.3 mm) than at 15 min (49.8 ± 2.2 mm); ratings at 30

min were intermediate (52.0 ± 2.2 mm). Similarly, post-meal thirst ratings changed over time (P

< 0.0001) but were not affected by treatment (P = 0.69) nor the time-by- treatment interaction (P

= 0.60). Following the test meal, thirst was immediately suppressed at 60 min (28.7 ± 2.2 mm)

from right before the test meal but steadily increased over time by 180 min (51.1 ± 2.7 mm) for

all treatments.

53

5.5.2 Change from Baseline Thirst Ratings

Change from baseline thirst ratings for Experiment 1 were affected by time (P = 0.01) but not

treatment (P = 0.80) (TABLE 5.11). Thirst was suppressed from baseline to a greater extent at

15 min following treatment consumption (-8.3 ± 2.4 mm) and 30 min (-7.5 ± 1.9 mm) than at 105

min (-0.6 ± 1.8 mm). The time-by-treatment interaction was significant (P < 0.0001); however,

mean change from baseline was similar for all treatments. This interaction was explained by the

inclusion of pre-meal water data in the analysis. A one-way ANOVA followed by Tukey-

Kramer‟s post-hoc test did not reveal any differences between control, low-, and high-sodium

beans at individual time points.

In Experiment 2, pre-meal thirst changed from baseline over time (P = 0.03) but no time-by-

treatment interaction was observed (P = 0.20) (TABLE 5.12). Thirst was suppressed more at 15

min than at 30 min from baseline for all treatments. Also, treatment did not affect thirst ratings

(P = 0.19). Following the test meal, the effect of time (P < 0.0001) was significant but not

treatment (P = 0.44) nor time-by-treatment (P = 0.76). Thirst was sharply reduced right before

the test meal (30 min) to immediately following its consumption (60 min) by 23.3 ± 2.9 mm.

Thirst ratings then steadily climbed near baseline levels by 180 min by an average increase of

22.4 mm for all treatments.

5.5.3 Thirst Net AUC

Thirst net AUC was not affected by treatment added-sodium content in either Experiment 1

(TABLE 5.13) or Experiment 2 (TABLE 5.14).

54

TABLE 5.11. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal thirst ratings1

Added-sodium content Time marginal mean


mm

Absolute ratings2

0 min 56.3 ± 5.3 55.6 ± 5.0 46.3 ± 5.7 50.6 ± 2.3ab

15 min 46.2 ± 5.6 46.8 ± 5.6 36.3 ± 6.1 42.2 ± 2.7c

30 min 45.4 ± 4.9 48.3 ± 5.1 39.3 ± 6.0 43.1 ± 2.4ab

45 min 48.6 ± 4.9 47.9 ± 5.0 41.5 ± 5.3 44.3 ± 2.3ab

60 min 50.8 ± 4.2 50.6 ± 5.1 38.5 ± 5.2 45.3 ± 2.3ab

75 min 50.1 ± 4.6 50.9 ± 3.9 43.2 ± 5.7 46.7 ± 2.2ab

105 min 54.1 ± 4.4 53.6 ± 4.3 47.2 ± 5.5 50.0 ± 2.3a

135 min 53.4 ± 5.4 53.0 ± 4.9 50.8 ± 5.4 44.1 ± 2.6bc

Treatment marginal mean 50.6 ± 1.7 50.8 ± 1.7 42.9 ± 2.0 --


15 min -10.1 ± 5.9 -8.8 ± 4.3 -9.9 ± 5.1 -8.3 ± 2.4a

30 min -10.9 ± 5.1 -7.3 ± 3.7 -6.9 ± 4.2 -7.5 ± 1.9a

45 min -7.8 ± 5.2 -7.7 ± 4.0 -4.8 ± 4.0 -6.3 ± 1.9ab

60 min -5.5 ± 4.9 -4.9 ± 3.3 -7.8 ± 4.4 -5.2 ± 1.7ab

75 min -6.2 ± 5.0 -4.7 ± 2.8 -3.1 ± 3.8 -3.8 ± 1.7ab

105 min -2.3 ± 4.2 -2.0 ± 3.6 0.9 ± 4.8 -0.6 ± 1.8b

135 min -2.9 ± 2.6 -2.6 ± 3.5 4.5 ± 4.5 -6.5 ± 1.9ab




2 Absolute two-factor ANOVA. Time (P = 0.006), treatment (P = 0.45) and time x treatment (P = 0.26). Treatment


3 Change from baseline two-factor ANOVA. Time (P = 0.01), treatment (P = 0.80) and time x treatment (P <


55


thirst ratings1

Added-sodium content

Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 63.6 ± 4.7 57.5 ± 5.0 59.8 ± 5.3 61.0 ± 6.4 52.0 ± 4.2 58.8 ± 2.3a

15 min 49.7 ± 5.0 51.8 ± 5.3 48.8 ± 4.0 50.4 ± 5.3 48.3 ± 5.6 49.8 ± 2.2b

30 min 52.1 ± 5.3 54.4 ± 5.2 50.4 ± 4.2 52.9 ± 5.2 50.3 ± 5.6 52.0 ± 2.2ab

Treatment

marginal mean 55.2 ± 3.0 54.5 ± 2.9 53.0 ± 2.6 54.8 ± 3.2 50.2 ± 2.9 --


60 min 27.1 ± 5.2 25.1 ± 4.7 32.3 ± 5.1 30.4 ± 5.1 28.8 ± 5.0 28.7 ± 2.2d

75 min 35.3 ± 5.5 33.9 ± 5.7 34.4 ± 5.2 36.5 ± 5.6 30.8 ± 4.3 34.2 ± 2.3cd

90 min 38.5 ± 5.1 36.9 ± 5.3 39.6 ± 4.7 42.1 ± 5.9 37.6 ± 4.5 38.9 ± 2.2bc

105 min 41.9 ± 5.4 42.5 ± 5.8 46.2 ± 4.4 39.6 ± 5.6 35.5 ± 5.4 41.1 ± 2.4abc

120 min 44.4 ± 6.1 43.1 ± 5.5 45.3 ± 5.1 41.6 ± 5.9 39.9 ± 5.3 42.9 ± 2.5abc

150 min 48.2 ± 5.5 47.8 ± 6.3 52.3 ± 4.6 46.1 ± 6.1 49.0 ± 5.7 48.7 ± 2.5ab

180 min 48.9 ± 6.7 45.6 ± 6.4 54.9 ± 5.2 52.5 ± 6.3 53.3 ± 5.8 51.1 ± 2.7a

Treatment

marginal mean 40.6 ± 2.2 39.3 ± 2.2 43.6 ± 1.9 41.3 ± 2.2 39.3 ± 2.0 --


15 min -13.9 ± 5.6 -5.7 ± 3.2 -10.9 ± 5.6 -10.6 ± 3.6 -3.7 ± 4.4 -9.0 ± 2.0b

30 min -11.5 ± 5.1 -3.1 ± 2.7 -9.4 ± 4.0 -8.1 ± 3.4 -1.7 ± 3.2 -6.8 ± 1.7a

Treatment

marginal mean -12.7 ± 3.8 -4.4 ± 2.1 -10.2 ± 3.4 -9.3 ± 2.5 -2.7 ± 2.7 --


60 min -25.0 ± 5.2 -29.3 ± 7.8 -18.1 ± 6.3 -22.5 ± 6.4 -21.4 ± 7.0 -23.3 ± 2.9d

75 min -16.8 ± 5.0 -20.4 ± 7.8 -16.0 ± 6.7 -16.4 ± 6.4 -19.4 ± 6.6 -17.8 ± 2.9cd

90 min -13.6 ± 4.6 -17.5 ± 7.1 -10.8 ± 5.7 -10.8 ± 6.1 -12.7 ± 7.3 -13.1 ± 2.7bc

105 min -10.2 ± 4.6 -11.8 ± 7.0 -4.2 ± 4.9 -13.3 ± 6.2 -14.7 ± 7.5 -10.9 ± 2.7abc

120 min -7.7 ± 5.1 -11.2 ± 7.2 -5.1 ± 5.8 -11.3 ± 5.9 -10.4 ± 7.1 -9.1 ± 2.8abc

150 min -3.9 ± 5.3 -6.6 ± 7.7 1.9 ± 5.3 -6.8 ± 5.9 -1.3 ± 7.8 -3.3 ± 2.9ab

180 min -3.2 ± 5.9 -8.7 ± 8.3 4.5 ± 5.6 -0.4 ± 5.8 3.1 ± 8.0 -0.9 ± 3.0a

Treatment

marginal mean -11.5 ± 2.0 -15.1 ± 2.9 -6.8 ± 2.2 -11.6 ± 2.3 -11.0 ± 2.8 --



2 Absolute two-factor ANOVA. Pre-meal: time (P = 0.03), treatment (P = 0.87) and time x treatment (P = 0.80).


3 Change from baseline two-factor ANOVA. Pre-meal: time (P = 0.03), treatment (P = 0.19) and time x treatment (P

= 0.20). Post-meal: time (P < 0.0001), treatment (P = 0.44) and time x treatment (P = 0.76).

56

TABLE 5.13. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal thirst areas

under the curve (AUC)1

Added-sodium treatment content Pre-meal thirst AUC2

mmmin

C (0 mg) -765.5 ± 555.5

LS (740 mg) -629.1 ± 358.8

HS (1480 mg) -393.3 ± 486.7

P3 0.96





and added-sodium treatments only. Thirst AUC: C vs. LS (P = 0.77); C vs. HS (P = 0.43); LS vs. HS (P = 0.62).


meal and cumulative thirst areas under the curve (AUC)1

Added-sodium

treatment content

Thirst AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg -294.9 ± 119.6 -1449.5 ± 607.4 -3264.1 ± 934.2

500 mg -108.6 ± 64.7 -1895.1 ± 916.6 -2315.5 ± 869.4

1000 mg -234.5 ± 110.7 -795.4 ± 694.9 -2312.0 ± 816.7

1500 mg -219.5 ± 75.8 -1451.8 ± 694.2 -2739.5 ± 867.2

2000 mg -68.3 ± 80.8 -1354.7 ± 889.0 -1584.9 ± 751.0

P 0.17 0.41 0.27




57

5.6 Blood Glucose Response

5.6.1 Absolute Blood Glucose Concentrations

In Experiment 1, absolute BG concentrations changed over time (P < 0.0001) but were not

affected by treatment (P = 0.28) nor was a time-by-treatment interaction observed (P = 0.52)

(TABLE 5.15). For all treatments, subjects arrived at baseline with similar fasting BG levels

(4.92 ± 0.04 mmol/L), which peaked between 45 min (5.92 ± 0.05 mmol/L) and 60 min (5.91 ±

0.06 mmol/L). Between 105 and 135 min, BG returned to fasting levels (5.27 ± 0.07 and 5.16 ±

0.05 mmol/L, respectively).

In Experiment 2, there was an effect of time (P < 0.0001) but not treatment (P = 0.71) nor time-

by-treatment interaction (P = 0.31) on pre-meal BG concentrations (TABLE 5.16). For all

treatments, baseline BG concentrations started at fasting levels (4.74 ± 0.04 mmol/L) and

significantly increased afterwards at 15 min (5.34 ± 0.05 mmol/L) and 30 min (5.88 ± 0.05

mmol/L). Similarly for post-meal BG response, only time (P < 0.0001) was significant but

neither treatment (P = 0.67) nor the time-by- treatment interaction (P = 0.45). Following the test

meal, BG concentrations peaked at 75 min (6.44 ± 0.09 mmol/L) but stabilized between 105 min

(5.99 ± 0.07 mmol/L) and 180 min (5.86 ± 0.05 mmol/L).

5.6.2 Change from Baseline Blood Glucose Concentrations

In Experiment 1, change from baseline BG concentrations were affected by time (P < 0.0001)

but not treatment (P = 0.87) or time-by-treatment interaction (P = 0.64) (TABLE 5.15).

Explaining the effect of time, subjects experienced the greatest increase in BG response to all

bean preloads between 45 min (0.98 ± 0.07 mmol/L) and 60 min (0.99 ± 0.07 mmol/L) from

baseline. BG concentrations steadily decreased by 135 min (0.23 ± 0.06 mmol/L).

In Experiment 2, pre-meal BG concentrations changed from baseline over time (P < 0.0001) but

was not affected by treatment (P = 0.24) nor time-by-treatment interaction (P = 0.25) (TABLE

5.16). For all treatments, subjects experienced a greater increase in BG concentrations at 30 min

58

(1.13 ± 0.06 mmol/L) than at 15 min (0.59 ± 0.05 mmol/L) from baseline. Following the test

meal, BG concentrations changed from baseline over time (P < 0.0001) but were unaffected by

treatment (P = 0.99) nor was the time-by-treatment interaction significant (P = 0.47). From

immediately before the test meal (30 min), all treatments resulted in the greatest increase in BG

concentrations at 75 min (0.57 ± 0.09 mmol/L). Afterwards, BG steadily decreased until falling

below 30-min baseline values between 150 min (-0.07 ± 0.05 mmol/L) and 180 min (-0.02 ±

0.05 mmol/L).

5.6.3 Blood Glucose Net AUC

BG net AUC was not affected by added-sodium content of the treatment in Experiment 1

(TABLE 5.17). However, in Experiment 2, cumulative BG net AUC (0 – 180 min) was affected

by treatment (P = 0.05) and tended to be highest after the 500 mg treatment (TABLE 5.18).

59


concentrations1



mmol/L

Absolute concentrations2

0 min 4.8 ± 0.1 4.9 ± 0.1 4.9 ± 0.1 4.9 ± 0.0d

30 min 5.7 ± 0.1 5.8 ± 0.1 5.7 ± 0.1 5.8 ± 0.1ab

45 min 5.9 ± 0.1 5.9 ± 0.2 5.9 ± 0.2 5.9 ± 0.1a

60 min 6.0 ± 0.2 5.9 ± 0.1 5.9 ± 0.2 5.9 ± 0.1a

75 min 5.7 ± 0.2 5.5 ± 0.1 5.7 ± 0.2 5.6 ± 0.1b

105 min 5.2 ± 0.2 5.2 ± 0.1 5.5 ± 0.2 5.3 ± 0.1bc

135 min 5.1 ± 0.1 5.0 ± 0.1 5.2 ± 0.1 5.2 ± 0.1cd


Change from 0 min concentrations3

30 min 0.8 ± 0.1 0.9 ± 0.1 0.8 ± 0.1 0.8 ± 0.1ab

45 min 1.0 ± 0.2 1.0 ± 0.2 1.0 ± 0.2 1.0 ± 0.1a

60 min 1.1 ± 0.2 1.0 ± 0.1 1.0 ± 0.2 1.0 ± 0.1a

75 min 0.9 ± 0.2 0.6 ± 0.1 0.8 ± 0.2 0.7 ± 0.1bc

105 min 0.4 ± 0.2 0.2 ± 0.1 0.6 ± 0.2 0.4 ± 0.1cd

135 min 0.2 ± 0.2 0.1 ± 0.1 0.3 ± 0.1 0.2 ± 0.1d








60


blood glucose concentrations1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mmol/L

Absolute pre-meal concentrations2

0 min 4.8 ± 0.1 4.6 ± 0.1 4.8 ± 0.1 4.8 ± 0.1 4.7 ± 0.1 4.7 ± 0.0c

15 min 5.2 ± 0.1 5.3 ± 0.1 5.4 ± 0.1 5.4 ± 0.1 5.3 ± 0.1 5.3 ± 0.0b

30 min 5.8 ± 0.1 5.9 ± 0.1 5.8 ± 0.1 5.9 ± 0.1 5.9 ± 0.1 5.9 ± 0.1a

Treatment

marginal mean 5.3 ± 0.1 5.3 ± 0.1 5.3 ± 0.1 5.4 ± 0.1 5.3 ± 0.1 --

Absolute post-meal concentrations2

60 min 6.2 ± 0.2 6.1 ± 0.2 5.9 ± 0.2 6.2 ± 0.2 6.1 ± 0.2 6.1 ± 0.1bc

75 min 6.6 ± 0.2 6.5 ± 0.2 6.5 ± 0.2 6.5 ± 0.2 6.2 ± 0.2 6.4 ± 0.1a

90 min 6.2 ± 0.2 6.4 ± 0.1 6.3 ± 0.2 6.4 ± 0.2 6.6 ± 0.3 6.4 ± 0.1ab

105 min 5.9 ± 0.2 6.1 ± 0.2 6.0 ± 0.2 5.9 ± 0.1 6.1 ± 0.2 6.0 ± 0.1c

120 min 5.9 ± 0.1 6.0 ± 0.2 5.8 ± 0.1 5.7 ± 0.1 6.0 ± 0.2 5.9 ± 0.1c

150 min 5.8 ± 0.1 6.0 ± 0.1 5.8 ± 0.1 5.7 ± 0.1 5.8 ± 0.1 5.8 ± 0.1c

180 min 5.9 ± 0.1 5.8 ± 0.1 5.8 ± 0.1 5.9 ± 0.1 5.9 ± 0.1 5.9 ± 0.0c

Treatment

marginal mean 6.0 ± 0.1 6.1 ± 0.1 6.0 ± 0.1 6.0 ± 0.1 6.1 ± 0.1 --

Change from 0 min pre-meal concentrations3

15 min 0.4 ± 0.1 0.7 ± 0.1 0.6 ± 0.1 0.6 ± 0.1 0.6 ± 0.1 0.6 ± 0.0b

30 min 1.0 ± 0.1 1.3 ± 0.1 1.0 ± 0.1 1.1 ± 0.1 1.2 ± 0.1 1.1 ± 0.1a

Treatment

marginal mean 0.7 ± 0.1 1.0 ± 0.1 0.8 ± 0.1 0.9 ± 0.1 0.9 ± 0.1 --

Change from 30 min post-meal concentrations3

60 min 0.4 ± 0.2 0.2 ± 0.2 0.1 ± 0.1 0.3 ± 0.2 0.2 ± 0.2 0.2 ± 0.1bc

75 min 0.7 ± 0.2 0.5 ± 0.2 0.7 ± 0.2 0.6 ± 0.1 0.3 ± 0.2 0.6 ± 0.1a

90 min 0.3 ± 0.2 0.5 ± 0.1 0.5 ± 0.2 0.5 ± 0.2 0.7 ± 0.4 0.5 ± 0.1ab

105 min 0.0 ± 0.2 0.2 ± 0.2 0.2 ± 0.2 -0.0 ± 0.2 0.2 ± 0.2 0.1 ± 0.1c

120 min 0.0 ± 0.1 0.1 ± 0.2 -0.0 ± 0.1 -0.2 ± 0.2 0.1 ± 0.2 0.0 ± 0.1c

150 min -0.1 ± 0.1 0.0 ± 0.1 -0.0 ± 0.1 -0.2 ± 0.1 -0.1 ± 0.1 -0.1 ± 0.1c

180 min 0.1 ± 0.1 -0.1 ± 0.1 0.0 ± 0.1 -0.1 ± 0.1 -0.0 ± 0.1 -0.0 ± 0.1c

Treatment

marginal mean 0.2 ± 0.1 0.2 ± 0.1 0.2 ± 0.1 0.1 ± 0.1 0.2 ± 0.1 --







61


areas under the curve (AUC)1

Added-sodium treatment content Pre-meal blood glucose AUC2

mmolmin/L

C (0 mg) 85.4 ± 20.3

LS (740 mg) 69.9 ± 12.1

HS (1480 mg) 87.4 ± 18.5

P3 0.57





and added-sodium treatments only. Blood glucose AUC: C vs. LS (P = 0.26); C vs. HS (P = 0.86); LS vs. HS (P =

0.58).


meal and cumulative blood glucose areas under the curve (AUC)1

Added-sodium

treatment content

Blood glucose AUC2

Pre-meal

Post-meal

Cumulative

mmolmin/L

0 mg 14.5 ± 2.4 25.2 ± 17.2 195.0 ± 15.6

500 mg 20.5 ± 2.5 23.7 ± 16.5 239.2 ± 23.5

1000 mg 16.5 ± 2.2 19.7 ± 15.4 190.0 ± 17.0

1500 mg 17.8 ± 1.9 10.9 ± 13.2 196.9 ± 14.4

2000 mg 17.6 ± 2.6 21.4 ± 17.6 216.7 ± 22.4

P 0.19 0.94 0.05




62

5.7 Physical Comfort

5.7.1 Absolute Average Physical Comfort Scores

In Experiment 1, absolute average physical comfort scores were not affected by time (P = 0.23),

treatment (P = 0.93), and time-by-treatment interaction (P = 0.27) (TABLE 5.19).

In Experiment 2, pre- and post-meal absolute physical comfort scores were not affected by time

(P = 0.08 and P = 0.65, respectively), treatment (P = 0.56 and P = 0.95, respectively) and time-

by-treatment interaction (P = 0.51 and P = 0.19, respectively) (TABLE 5.20).

5.7.2 Change from Baseline Average Physical Comfort Scores

In Experiment 1, change from baseline average physical comfort scores were not affected by

time (P = 0.11), treatment (P = 0.10) and time-by-treatment interaction (P = 0.23) (TABLE

5.19). However, low-sodium beans resulted in a decrease in physical comfort over time (-2.2 ±

1.2 mm) compared to control (1.9 ± 1.2 mm) and high-sodium beans (2.8 ± 1.4 mm) (P = 0.03

and P = 0.02, respectively).

In Experiment 2, pre- and post-meal physical comfort scores did not change from baseline over

time (P = 0.96 and P = 0.08, respectively) and were not affected by treatment (P = 0.67 and P =

0.06, respectively) and time-by-treatment (P = 0.15 and P = 0.55, respectively) (TABLE 5.20).

5.7.3 Average Physical Comfort net AUC

In Experiment 1, physical comfort AUC (0 – 135 min) was most reduced after consumption of

low-sodium beans (-276.5 ± 258.7 mmmin) compared with high-sodium beans (388.9 ± 282.1

mmmin) (P = 0.02) (). Control beans led to an intermediate response (232.9 ± 232.8 mmmin)

(TABLE 5.21).

In Experiment 2, physical comfort AUC was not affected by treatment added-sodium content

(TABLE 5.22).

63


physical comfort scores1



mm

Absolute ratings2

0 min 82.6 ± 4.4 86.0 ± 2.9 82.3 ± 3.5 83.0 ± 1.7

15 min 83.8 ± 4.0 81.9 ± 4.2 84.2 ± 3.8 82.7 ± 1.9

75 min 84.5 ± 4.1 84.3 ± 3.7 86.5 ± 3.4 84.5 ± 1.7

135 min 85.2 ± 2.9 85.2 ± 3.5 84.7 ± 3.9 85.0 ± 1.6



15 min 1.2 ± 1.2 -4.1 ± 2.1 1.9 ± 2.4 -0.3 ± 1.0

75 min 1.9 ± 2.2 -1.7 ± 2.2 4.2 ± 2.1 1.5 ± 0.9

135 min 2.6 ± 2.5 -0.7 ± 2.0 2.4 ± 2.7 1.9 ± 1.1

Treatment marginal mean 1.9 ± 1.2a -2.2 ± 1.2

b 2.8 ± 1.4

a --





3 Change from baseline two-factor ANOVA. Time (P = 0.11), treatment (P = 0.10) and time x treatment (P = 0.23).

Treatment effect: C vs. LS (P = 0.03); C vs. HS (P = 0.79); LS vs. HS (P = 0.02).

64


average physical comfort scores1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 87.3 ± 3.0 88.8 ± 2.6 86.5 ± 2.7 88.0 ± 2.8 89.5 ± 2.0 88.0 ± 1.2

15 min 85.9 ± 2.9 87.0 ± 2.7 86.4 ± 2.9 85.1 ± 3.2 86.8 ± 2.6 86.2 ± 1.3

30 min 86.7 ± 2.9 85.2 ± 2.9 87.5 ± 2.2 84.6 ± 3.5 87.2 ± 2.4 86.2 ± 1.2

Treatment

marginal mean 86.6 ± 1.7 87.0 ± 1.6 86.8 ± 1.5 85.9 ± 1.8 87.9 ± 1.3 --


60 min 86.4 ± 3.2 87.0 ± 2.5 85.7 ± 3.0 85.6 ± 3.7 86.5 ± 2.8 86.3 ± 1.3

75 min 84.3 ± 3.4 86.4 ± 2.6 86.2 ± 2.8 86.7 ± 3.0 84.8 ± 3.1 85.7 ± 1.3

90 min 87.1 ± 3.1 88.5 ± 2.3 88.1 ± 2.3 86.7 ± 3.5 86.1 ± 2.8 87.3 ± 1.2

105 min 85.7 ± 3.1 88.1 ± 2.4 88.2 ± 2.1 87.3 ± 2.9 85.4 ± 3.2 86.9 ± 1.2

120 min 86.2 ± 3.3 87.9 ± 2.1 87.9 ± 2.2 86.9 ± 3.0 85.4 ± 3.4 86.9 ± 1.2

150 min 87.3 ± 2.9 88.5 ± 2.2 88.8 ± 1.9 88.5 ± 2.8 86.7 ± 2.4 88.0 ± 1.1

180 min 88.8 ± 2.2 89.1 ± 2.1 88.1 ± 2.2 86.4 ± 3.0 88.8 ± 1.9 88.3 ± 1.0

Treatment

marginal mean 86.6 ± 1.1 87.9 ± 0.9 87.6 ± 0.9 86.9 ± 1.2 86.3 ± 1.1 --


15 min -1.4 ± 1.6 -1.8 ± 1.2 -0.1 ± 1.6 -2.9 ± 2.1 -2.5 ± 1.4 -1.7 ± 0.7

30 min -0.7 ± 2.4 -3.6 ± 1.6 1.0 ± 1.5 -3.4 ± 1.8 -2.4 ± 1.4 -1.8 ± 0.8

Treatment

marginal mean -1.1 ± 1.4 -2.7 ± 1.0 0.4 ± 1.1 -3.2 ± 1.4 -2.4 ± 1.0 --


60 min -0.2 ± 1.7 1.8 ± 1.2 -1.8 ± 1.8 1.1 ± 1.9 -0.6 ± 1.8 0.0 ± 0.8

75 min -2.4 ± 1.8 1.2 ± 1.4 -1.3 ± 1.8 2.2 ± 1.4 -2.3 ± 1.9 -0.5 ± 0.8

90 min 0.5 ± 2.0 3.4 ± 1.2 0.6 ± 1.4 2.1 ± 2.0 -1.1 ± 2.3 1.1 ± 0.8

105 min -0.9 ± 2.2 2.9 ± 1.5 0.7 ± 1.1 2.8 ± 1.5 -1.7 ± 2.7 0.7 ± 0.8

120 min -0.4 ± 1.8 2.7 ± 1.4 0.4 ± 0.9 2.3 ± 1.7 -1.7 ± 2.6 0.6 ± 0.8

150 min 0.6 ± 2.1 3.4 ± 1.7 1.3 ± 0.9 3.9 ± 1.9 -0.4 ± 1.5 1.8 ± 0.7

180 min 2.2 ± 1.8 3.9 ± 1.7 0.6 ± 1.1 1.8 ± 2.9 1.7 ± 1.4 2.0 ± 0.8

Treatment

marginal mean -0.1 ± 0.7 2.8 ± 0.5 0.1 ± 0.5 2.3 ± 0.7 -0.9 ± 0.8 --




Post-meal: time (P = 0.65), treatment (P = 0.96) and time x treatment (P = 0.19).


= 0.15). Post-meal: time (P = 0.08), treatment (P = 0.06) and time x treatment (P = 0.55).

65

TABLE 5.21.Exp 1: Effect of sodium content of a solid food (beans) on pre-meal average

physical comfort areas under the curve (AUC)1

Added-sodium treatment content Pre-meal average physical comfort AUC2

mmmin

C (0 mg) 232.9 ± 232.8ab

LS (740 mg) -276.5 ± 258.7b

HS (1480 mg) 388.9 ± 282.1a

P3 0.12





and added-sodium treatments only. Physical comfort AUC: C vs. LS (P = 0.12); C vs. HS (P = 0.60); LS vs. HS (P =

0.04).


meal and cumulative average physical comfort areas under the curve (AUC)1

Added-sodium

treatment content

Average physical comfort AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg -26.6 ± 38.0 -6.7 ± 231.4 -132.8 ± 275.8

500 mg -53.8 ± 28.1 373.7 ± 174.5 -221.6 ± 221.9

1000 mg 5.7 ± 31.2 13.5 ± 136.4 167.6 ± 212.6

1500 mg -70.0 ± 43.4 327.8 ± 213.4 -258.6 ± 221.0

2000 mg -56.8 ± 27.9 -117.7 ± 242.2 -586.3 ± 259.2

P 0.41 0.34 0.21




66

CHAPTER 6 DISCUSSION, CONCLUSION AND FUTURE DIRECTIONS

6

6.1 Discussion

The results of these studies do not support the hypothesis that sodium content of a food or

beverage increases acute ad libitum food and water intakes, subjective appetite and thirst, and

blood glucose concentrations. Some statistically significant effects were observed between

treatments but these are difficult to interpret because no treatment effect differed from controls.

The two studies presented in this thesis are the first to report the simultaneous effects of a range

of sodium content of a solid food or beverage on acute subjective appetite and thirst, ad libitum

food and water intakes at a later meal, and postprandial glycemic responses in healthy young

men. Furthermore, both studies provided treatments covering a wide range of sodium doses

differing in food matrix form; and tested different timeframes between treatment consumption

and measurement of dependent outcomes that spanned the possible period during which acute

effects of sodium intake can be observed [16, 18, 83]. An added strength to Experiment 2 was

the measurement of post-meal subjective ratings of appetite and thirst as well as blood glucose

for 120 minutes, allowing both pre- and post-meal assessments of the effect of treatment sodium

content.

Although the range of sodium was different between the two studies, the wide range of sodium

content of the treatments strengthens the conclusion that adding sodium either to a solid food or

beverage has little significant short-term effect on food and water intake regulation as well as

glycemic response. The maximum amount of sodium provided in the treatments approached the

recommended daily UL of 2300 mg [33] in one single serving, which was as high as 2000 mg in

Experiment 2. Furthermore, cumulative sodium intake (treatment and test meal) was as high as

4919 mg (12.5 g salt) for the 2000 mg tomato beverage. Some treatment effects of statistical

significance were observed but they were inconsistent between the two experiments, with some

indication that high- and low-sodium content of the treatments differed from each other in some

effects while none differed from their controls. Specifically, the higher dose of sodium added to

beans (1480 mg) led to lower caloric intake 120 min later and reduced appetite compared with

67

the low-sodium treatment (740 mg) but not compared with the no-added-sodium control. Of note

is that baseline average appetite was different between control and added-sodium beans and the

difference in average appetite means between low- and high-sodium beans did not emerge when

values were calculated as change from baseline. However, after adjusting for baseline average

appetite scores, food intake still tended to be lower following intake of high- versus low-sodium

beans (P = 0.09) (Appendix 8.2 TABLE 8.14). In Experiment 2, when 2000 mg of sodium was

added to a tomato beverage, water intake was higher at the meal served at 30 min compared with

the 500 mg treatment while food intake and appetite were similar across all treatments. Although

these findings are difficult to integrate, they suggest that there may be a U-shaped response to

added-sodium content, which merits further exploration [145]. One early study reported that

gastric emptying after sodium intake followed a curve, which is slow at the start when sodium

content is low (i.e. 0 mg) but increases as sodium content increases up to 250 mOsm

(approximately 2200 mg) after which gastric emptying again slows down and later plateaus [16].

This pattern in gastric emptying may therefore be echoed in subjective and quantitative

responses related to food and water intakes.

Because of the different food matrices (i.e. solid versus liquid), different times were chosen to

give the test meal, which may have contributed to the divergent food and water intake results for

these two experiments yet also added strength to the conclusion. Food intake was measured at

120 min after treatment consumption in Experiment 1 because of prior research that showed that

healthy young males had higher thirst ratings over 120 min associated with higher sodium

content in canned pulse treatments [137]. Also, one study [18] reported that normal and

overweight Caucasian adults (19-50 years old, 19-31 kg/m2) who consumed sodium (9.4 mg/kg

body) added to a dairy based-beverage experienced increased appetite between 90 and 150 min

after consumption compared to the same beverage given with calcium carbonate instead;

however, ad libitum food intake at a later meal was not tested. For perspective, approximately

676 mg would have been administered based on the average body weight of subjects in

Experiment 1 (71.6 ± 1.3 kg). In contrast, in Experiment 1, higher subjective appetite ratings

along with food intake followed the bean treatment with 740 mg added-sodium but only in

comparison to the high-sodium treatment of 1480 mg. On the other hand, Experiment 2 assessed

food intake 30 min after treatments because a previous study [83] showed that intake of 2300 mg

68

sodium added to water versus water alone increased plasma sodium concentrations and

osmolality above normal levels as well stimulated the release of sodium balance hormones

within 30 min. Moreover, decreased rate of gastric emptying was observed over 20 min

following intake of 2200 mg or more of sodium chloride or sodium bicarbonate added to 750 mL

of distilled water [16]. Therefore, Experiment 2 was based on the hypothesis that if sodium

absorption and plasma concentrations stimulate satiety-related mechanisms, sodium would have

been expected to do so during the 30 min inter-meal interval in this study. It is possible that the

tomato paste beverage, which contained a small amount of dietary fibre (3.5 g), may have

slowed down sodium absorption and thereby occluded potential effects on satiety-related

mechanisms and differences between control and added-sodium treatments up to the time of the

meal at 30 min. However, if this had occurred, it would be expected that an effect would have

emerged post-meal in Experiment 2. Cumulative average sodium intake ranging between 3000 to

5000 mg up to meal completion (60 min after baseline) in fact had no effect on subjective

appetite scores for the 120 min period following the test meal.

It is perhaps surprising that the added-sodium content of the treatments had little effect on water

intake at the test meal in either study. No statistical differences between control and added-

sodium beans were observed in Experiment 1. In Experiment 2, water intake was higher only

after the highest sodium treatment (2000 mg) compared with the 500 mg treatment but not

compared with the control, similar to the pattern observed for food intake in Experiment 1

between low- and high-sodium beans. It should be noted that it is not known if subjects drank

water immediately when they were presented the pizza meal, which would have likely been a

direct response to treatment sodium content; or if they alternated between eating and drinking,

which would have allowed the pizza sodium content to influence water intake. In either case, the

largest difference in water intake was only 77 g even though added-sodium content of the

beverages was as high as 2000 mg and cumulative (treatment and test meal) sodium intake

increased with increasing treatment sodium content, reaching as high as 4919 mg (12.5 g salt) for

the 2000 mg added-sodium beverage. These findings also suggest that drinking water during a

meal does not reduce simultaneous food intake given that food intake was similar across all

treatments in spite of water intake differences. This agrees with previous findings indicating that

69

neither caloric and non-caloric beverages nor liquid volume affect energy intake at the same

meal [146].

Subjective thirst ratings prior to the test meal also remained unaffected by sodium content in

both trials. This suggests that even if plasma sodium concentrations and osmolality increased

above normal physiological concentrations within 30 min [76] in Experiment 2, as with post-

meal subjective appetite, there was no effect of cumulative sodium intake between 3000 and

5000 mg on post-meal thirst ratings. While this may seem surprising, this observation is

consistent with the lack of associations found by others between subjective thirst ratings and

fluid intake when assessed over 24 hours daily for 7 days [13, 147]. Ingestive events occurred

inappropriately on about 62% of occasions, such as subjects eating and drinking when they

responded “not thirsty” or “not hungry.” Moreover, participants reported drinking water in

response to thirst in the absence of hunger on 2% of occasions but ate in response to hunger

when not thirsty 68% of the time, reflecting a tighter relationship between appetite-eating than

thirst-drinking. This supports the present findings in that appetite and food intake changed in

sync in Experiment 1 but water intake was not associated with thirst ratings in Experiment 2. It

should be highlighted that fluid intake and hydration status were partly controlled for at baseline

in both studies by providing each subject with a fixed amount of bottled water (500 mL) to

consume during breakfast before arriving to the laboratory before each session.

Finally, sodium did not affect postprandial blood glucose concentrations in normoglycemic

individuals. A marginal statistically significant effect of treatment (P = 0.05) on cumulative (pre-

and post-meal) blood glucose AUC was found in Experiment 2 but no differences among

treatments were identified by Tukey‟s post hoc test. This finding requires further investigation

because it suggests that sodium may have an effect on post-meal blood glucose given that food

intake was statistically similar across all treatments and does not significantly account for this

treatment difference. However, no effects of treatment were observed either pre-meal

(Experiment 1 and 2) or post-meal in Experiment 2. Because absorption of glucose and sodium

are intimately linked [21, 22, 24, 25], it was expected that higher sodium content would increase

glucose absorption. However, the higher sodium concentrations in the stomach may have

delayed gastric emptying and nutrient absorption, which would slow down glucose entry to the

70

small intestine, thus diminishing the effect of sodium on increasing glucose absorption. Also,

both treatment vehicles had fibre (22 g in beans and 3.5 g in tomato juice) and contained tomato-

based ingredients. Fresh tomatoes and tomato products are also rich in pectin [148], which

reduces both sodium and glucose absorption [117]. Therefore, the fibre content of the beans and

tomato juice may have blunted glycemic responses similar to other acute studies that tested high-

fibre foods. However even if this occurred, the high cumulative sodium intake of treatment plus

test meal failed to affect post-meal blood glucose concentrations measured over two hours in

Experiment 2. Thus, it can be concluded that sodium intake over the ranges tested does not elicit

acute effects on blood glucose concentrations.

Together with the available literature, the present studies support the idea that carbohydrate

content is a much stronger influence on glycemic response than sodium content. Although the

available carbohydrate intake was relatively low in these studies (33 g in Experiment 1 and 11 g

in Experiment 2), the results are similar to other reports. A previous study in healthy adults [27]

observed that lima beans led to low and stable postprandial blood glucose and insulin responses

over 180 min compared to higher glycemic foods (mashed potatoes and rice) whether the three

foods providing 50 g of available carbohydrates were consumed without or with 1678 mg of

added-sodium. Similarly, mean peak plasma glucose concentrations and AUCs were lowest for

black-eyed beans yet highest for a glucose solution whether each treatment providing 75 g of

available carbohydrates was consumed without or with 1668 mg added-sodium [28]. In

hindsight, negative controls (i.e. white bread; glucose solution) should have been provided to

firmly conclude that sodium had no glycemic effects. It should also be noted that all of these

studies including the two presented here were carried out in a young, healthy population that had

normal glucose tolerance and body weight and results may be different in subjects with insulin

resistance and diabetes. Research is limited on other populations but one trial carried out in

children (15 years old or below) with stable type I diabetes similarly observed no differences in

blood glucose concentrations over 180 min following ingestion of a 75 g oral glucose solution

without or with 1967 mg added-sodium [121].

Sensory factors including food palatability play an early role in the termination of a meal

(satiation) [149] but was an unlikely factor in these studies for several reasons. First, only weak

71

effects of salt content on palatability were observed in both studies. (P = 0.06 for high-sodium

versus control in Experiment 1; P = 0.07 in Experiment 2). Second, within each experiment,

factors that influence food intake regulation and satiety such as energy density [150] and nutrient

composition [89] were controlled for by using the same treatment vehicle across all preloads.

Third, when treatment palatability was included as a covariate in statistical analyses for food

intake and average appetite, the significance remained the same (Appendix 8.2 TABLE 8.13).

Although the present studies do not support the hypothesis that acute salt intake affects blood

glucose, high salt intake may indeed affect glycemic control over time according to salt

sensitivity, age, obesity and race. Longer-term studies indicate that high sodium intake may

initially improve but later dysregulate glycemic control. In healthy lean adults, a high-sodium

(4600 mg) diet for six days significantly increased insulin-mediated glucose-uptake compared to

a low-sodium (460 mg) diet, reflecting improved insulin sensitivity in healthy men and women

[122]. In contrast, salt-sensitive elderly volunteers developed insulin resistance after high-

sodium intake for 13 weeks even though they initially experienced improved insulin sensitivity

compared to a low-sodium diet [123].

Similarly, the lack of acute effects of added-sodium content in solid foods or beverages on short-

term subjective appetite and thirst and on ad libitum food and water intakes cannot be

extrapolated to its effects on these parameters under chronic conditions, and thus chronic disease.

However, at the present time the role of sodium in chronic disease remains a matter of debate,

suggesting that more research is required to understand short-term physiological effects of salt

intake to more fully inform public health policy. A recent Cochrane review of the effect of

sodium intakes on cardiovascular disease has concluded that there is insufficient evidence to

support that lowering population average intakes below 2300 mg/day will lead to benefits [145]

and may have adverse effects as shown by a J-shaped curve between intakes and cardiovascular

disease [145].

72

6.2 Conclusion

In summary, the addition of sodium to a solid food (beans) or beverage (tomato juice) does not

increase ad libitum food or water intakes, subjective ratings of appetite or thirst, or blood glucose

in healthy young adults.

6.3 Future Directions

As noted earlier, these studies are the first designed to examine the effects of acute sodium

chloride intake on ad libitum food and water intakes, subjective ratings of appetite and thirst, and

blood glucose in healthy young adults. As such, the results are novel and highlight the need for

additional randomized control trials examining a range of acute and long-term sodium intake.

This is necessary because current sodium reduction strategies are heavily influenced by

observational evidence linking sodium to cardiovascular health. However, it is concerning some

experts that curtailing sodium intakes, especially in a drastic manner, may lead to health

complications [145], which can be revealed by appropriately designed clinical studies.

Based on the present findings, additional studies are needed to clarify if the differences between

low- and high- added-sodium treatments on food intake, appetite and water intake are directly

due to sodium. If sodium content of foods and beverages does affect acute subjective and

quantitative measures of energy and fluid intakes, it would be necessary to test a range of sodium

in both solids and liquids within the same study as well as assess biomarkers related to food and

fluid intake regulation like GLP-1 and ADH. Future treatment vehicles can also include a mix of

low- and high-glycemic foods and beverages to better assess the links between sodium and

available carbohydrate content.

Because of the high cumulative sodium intakes in both studies, it would be interesting to

determine if subjects alter their food choices at a later meal provided as a buffet rather than a

fixed one-choice meal in order to control their sodium intake. Although it cannot be concluded

from the present studies, it may be that food intake was weakly affected as a result of subjects

eating more or less sodium at the pizza meal depending on the sodium content of their

treatments. Similarly for fluid intake regulation, a variety of caloric and non-caloric beverages

73

could be presented at a later meal to see if treatment sodium content affects subsequent beverage

choice and volume consumed.

Another relevant direction is to understand if changes in chronic dietary sodium intake affect

energy intake patterns. Abrupt reductions in daily sodium intake have been found to elevate

plasma levels of aldosterone and angiotensin within a couple of weeks [151, 152] , two

hormones that stimulate salt appetite [72, 110]. Over time, a low-sodium diet also leads to lower

salt preferences [98] but it is not yet proven if these sensory changes reduce ad libitum ingestion

of salty foods, significantly alter food intake and/or promote weight loss.

Sodium may not strongly affect acute blood glucose responses in healthy adults but given the

available literature, a future direction would be to elucidate the chronic effects of low-, normal-,

and high-sodium intake on glucose control and insulin sensitivity in populations varying in age,

weight and ethnicity. This will help policy makers understand if universal sodium reduction

strategies will be beneficial for everyone or instead harm those who already adhere to

recommended intakes by leading to conditions indirectly related to cardiovascular health [145].

Finally, variables that are relevant to sodium‟s biological effects should be taken into account of

in future studies. Subjects‟ salt sensitivity and their salt taste acuity and threshold should be

estimated because the manner in which their taste and blood pressure change in response to

dietary sodium intake may be related to potential effects on other physiological parameters.

Similarly, background diet can be surveyed via dietary food intake records or questionnaires to

determine their habitual sodium intakes, which is known to affect food selection [97]. Two

additional variables that should be controlled for are hydration and sodium excretion since acute

fluctuations in sodium and plasma volume can influence hormonal responses [109]. The present

studies did provide each subject with a fixed amount of bottled water (500 mL) to be consumed

during the 4-hour period before arriving to the laboratory for each session. However, water

drinking can instead be controlled for at the test site in order to ensure subject compliance. Urine

samples can also be collected to account for recent sodium intake and excretion.

74

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CHAPTER 8 APPENDICES

8

8.1 Appendix I: The Effects of Pre-meal Water Intake on Acute Food and Water Intakes (Experiment 1b)

8.1.1 Background and Rationale

It is estimated that nearly two-thirds of Canadians (14.1 million) are overweight or obese [86].

Obesity is a major risk factor for the metabolic syndrome, which is linked to conditions such as

type II diabetes. Dietary interventions that increase satiety (to promote weight loss) and maintain

normal blood glucose levels are noninvasive and inexpensive compared to pharmacological

strategies. Thus, it is important to identify strategies that contribute to healthy body weight by

increasing satiety and thereby reducing food intake.

One purported weight-loss tactic is drinking water. It is thought that individuals confuse thirst

and hunger signals by eating when they feel thirsty. However, this is unclear given that

dehydration has been found to reduce food intake because of circulating anti-diuretic hormone

[153] released in response to intracellular thirst (Section 2.7.1). More recent findings have linked

WI with a lower BMI [147] and long-term maintenance of body weight [154], which could be

due to the replacement of sugary drinks with water [14, 155]. It is thought that liquid calories are

not satiating [78], which can override appetite regulatory mechanisms and prompt unrestrained

intake of solid calories [79]. Overweight individuals also generally tend to drink less water than

lean individuals [13] although reasons for this trend are not yet clear. In addition to replacing

caloric drinks, WI may affect energy balance through stimulation of thermogenesis. In the acute,

overweight/obese adults who were otherwise healthy expended 24% more energy over 60 min

following intake of 500 mL of regular tap water compared to 500 mL of salted water and 50 mL

of regular tap water [156, 157].

Meanwhile, drinking water before a meal may lead to negative energy balance in the acute by

distending the stomach. The principle reason underlying this hypothesis is that gastric distention

activates satiety circuitry in the brain that increases feelings of fullness [158]. This implies that

84

drinking water is satiating compared to no water intake. Paradoxically, large volumes of water

and other liquids low in nutrients have been reported to empty at a faster rate than smaller

volumes [159]. Consumption of a fixed amount of water (375 to 600 mL) 30 min before an ad

libitum meal reduces ad libitum FI in normal weight [160] and obese [161] older adults but not in

younger adults. Rolls and colleagues [162] also found that young normal weight adult men

consumed the same amount of energy whether they drank 250 mL or 500 mL of either water or

non-caloric lemonade sweetened with aspartame 30 min before a buffet meal. Similarly, a

separate study by Anderson and colleagues [163] found that 560 mL of an aspartame-sweetened

soft drink reduced hunger ratings for 30 min after ingestion compared to 280 mL of the same soft

drink or 280 mL of mineral water. However, FI at a meal served 60 min after beverage intake did

not differ amongst conditions. A limitation of this study is that a no-beverage preload condition

was not provided for comparison.

Differences in age and physiology between participants may explain the benefits of WI in older

individuals; and perhaps pre-meal WI has no effects whatsoever in younger populations.

However, the available literature may be constrained by previous study protocols. If pre-meal WI

influences FI regulation, it is possible that the administration of water and other non-caloric

beverages 30 to 60 min before the test meal in younger individuals left ample time for satiating

effects like gastric distention to wear off. No study has reported the effect of a range of WI

ingested at a time closer to the meal in healthy young adults.

8.1.2 Hypothesis

Drinking water 10 min before a meal decreases ad libitum FI and WI as volume of water

increases.

8.1.3 Objectives

The objective was to investigate the effects of pre-meal water intake on (1) FI and WI at a meal

provided 10 min later; and (2) BG, SA and thirst immediately before the meal.

85

8.1.4 Materials and Methods

The investigation of pre-meal water intake was a secondary objective of Experiment 1.

Therefore, subjects (Section 4.1), treatment composition (Section 4.2.1), experimental protocol

(Section 4.3) and dependent measures (Section 4.4) were identical to those for the investigation

of sodium content of a solid food as previously described. The two objectives of Experiment 1

differed with respect to the study design. To understand the effects of pre-meal water intake,

subjects drank 0 mL (control; C), 150 mL (low-water; LW) or 500 mL (high-water; HW) of

distilled water 10 min before the pizza meal served at 135 min after baseline. Prior to that, they

consumed control beans at 0 min (0 mg added-sodium) to maintain consistency between the

added-sodium conditions. LW and HW volumes were chosen to reflect the amounts of pre-meal

water consumed by young adults in previous pulse [137] and beverage [160] studies,

respectively.

8.1.5 Statistical Analysis

For Experiment 1, a priori comparisons were made to compare added-sodium treatments to

control and pre-meal water treatments to control. Although subjects received the five treatments

in random order, the effects of sodium addition and water consumption prior to the meal were

examined independently. Thus, orthogonal contrasts were used to determine the independent

effects of added-sodium and pre-meal water intake to no-added sodium bean preloads on all

dependent measures. The contrasts between pre-meal water intake and the no beverage preload

control were: 1) 0 mL vs. 150 mL; 2) 0 mL vs. 500 mL; and 3) 150 mL vs. 500 mL. Data for all

five preload conditions were included to estimate the pooled variance for determining

significance of treatments.

8.1.6 Results

In Experiment 1, 150 mL and 500 mL of water consumed 10 min before the pizza meal as pre-

meal water are referred to as low-water (LW) and high-water (HW) treatments. Subject

characteristics were previously described (Section 5.1).

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8.1.6.1 Treatment and Test Meal Palatability

Control beans were consumed at baseline for both pre-meal water conditions, and drinking water

before the ad libitum test meal did not affect treatment palatability (TABLE 8.1.). The ad

libitum pizza meal was rated pleasant regardless of pre-meal water intake (TABLE 8.1.).

8.1.6.2 Food, Sodium and Water Intakes

FI was 131 and 178 kcal higher following intake of low-water compared with both control (P =

0.03) and high-water (P = 0.004), respectively (TABLE 8.2). FI for control and high-water were

comparable (P = 0.40). As a result, sodium intake at the pizza meal paralleled energy intake and

was 289 and 446 mg higher after intake of low-water before the pizza meal compared to control

(P = 0.04) and high-water (P = 0.002), respectively (TABLE 8.2). Sodium intake for control and

high-water were comparable (P = 0.25). Approximately 125 and 106 mL less water was ingested

at the pizza meal following 500 mL pre-meal water intake compared to both control (P = 0.0001)

and 150 mL (P = 0.0003), respectively; however, cumulative water intake increased as pre-meal

water intake increased (TABLE 8.2).

8.1.6.3 Absolute Average Appetite Scores

Time (P < 0.0001) and treatment (P = 0.01) affected absolute average appetite but no time-by-

treatment interaction was observed (P = 0.11) from 0 to 135 min (TABLE 8.3). Irrespective of

treatment sodium content, average appetite was highest at baseline (68.7 ± 1.8 mm) but

immediately decreased following consumption of bean preloads (42.5 ± 2.2 mm) and gradually

returned to baseline levels by 135 min (65.1 ± 2.0 mm). Appetite ratings for control (54.2 mm),

low-water (53.0 mm) and high-water (54.8 mm) from 0 to 135 min were comparable. Moreover,

drinking water 10 min before the pizza meal did not affect average appetite immediately before

the meal at 135 min.

8.1.6.4 Change from Baseline Average Appetite Scores

Change from baseline appetite ratings were affected by time (P < 0.0001) and treatment (P =

0.0006) but no time-by-treatment was detected (P = 0.48) over 135 min (TABLE 8.3). Average

87

appetite was suppressed at 15 min after baseline (-23.4 ± 2.2 mm) and ratings gradually

increased to near baseline levels by 135 min (-3.6 ± 1.8 mm) for all treatments. Although water

was ingested 10 min before the pizza meal, participants reported a larger decrease in average

appetite ratings over 135 min when they received high-water (-22.1 ± 1.7 mm) compared with

control (-15.4 ± 1.9 mm) (P = 0.008). Mean average appetite for control and low-water were

similar (P = 0.10).

8.1.6.5 Average Appetite Net AUC

Subjects felt less appetite from 0 to 135 min when they received high-water before the pizza

meal compared to control (P = 0.03) (TABLE 8.4). Appetite AUCs were comparable between

low-water and control (P = 0.27) and low-water and high-water (P = 0.26).

8.1.6.6 Absolute Thirst Ratings

Absolute thirst ratings were affected by time (P = 0.006) but not treatment (P = 0.45) nor time-

by-treatment (P = 0.26) (TABLE 8.5). Explaining the effect of time, thirst was higher at 0 min

(50.6 ± 2.3 mm) and 105 min (50.0 ± 2.3 mm) than at 15 min (42.2 ± 2.7 mm); and higher at 105

min than at 135 min (44.1 ± 2.6 mm).

8.1.6.7 Change from Baseline Thirst Ratings

After determining change from baseline thirst ratings, the effect of time was significant (P =

0.01) but not treatment (P = 0.80) (TABLE 8.5). Thirst was suppressed from baseline to a

greater extent at 15 min following treatment consumption (-8.3 ± 2.4 mm) and 30 min (-7.5 ± 1.9

mm) than at 105 min (-0.6 ± 1.8 mm). The time-by-treatment interaction was significant (P <

0.0001), which was attributable to 500 mL pre-meal water reducing thirst to a greater extent at

135 min compared with both 0 mL (P = 0.0006) and 150 mL (P = 0.05).

8.1.6.8 Thirst Net AUC

Pre-meal water intake did not affect thirst net AUC (TABLE 8.6).

88

8.1.6.9 Absolute Blood Glucose Concentrations

Absolute BG concentrations changed over time (P < 0.0001) but were not affected by overall

treatment (P = 0.28) nor time-by-treatment (P = 0.52) (TABLE 8.7). For all treatments, subjects

arrived at baseline with similar fasting BG levels (4.92 ± 0.04 mmol/L), which peaked between

45 min (5.92 ± 0.05 mmol/L) and 60 min (5.91 ± 0.06 mmol/L). Between 105 and 135 min, BG

returned to fasting levels (5.27 ± 0.07 and 5.16 ± 0.05 mmol/L, respectively).

8.1.6.10 Change from Baseline Blood Glucose Concentrations

BG concentrations changed from baseline over time (P < 0.0001) but were not influenced by

treatment (P = 0.87) nor was the time-by-treatment interaction significant (P = 0.64) (TABLE

8.7). Explaining the effect of time, subjects experienced the greatest increase in BG response to

all bean preloads between 45 min (0.98 ± 0.07 mmol/L) and 60 min (0.99 ± 0.07 mmol/L) from

baseline. BG concentrations steadily decreased by 135 min (0.23 ± 0.06 mmol/L).

8.1.6.11 Blood Glucose Net AUC

Pre-meal water intake did not affect BG net AUCs (TABLE 8.8).

8.1.6.12 Absolute Average Physical Comfort Scores

Absolute average physical comfort scores did not vary over time (P = 0.23) nor were they

affected by treatment (P = 0.93). In addition, no time-by-treatment interaction was observed (P =

0.27) (TABLE 8.9).

8.1.6.13 Change from Baseline Average Physical Comfort Scores

Average physical comfort scores did not change from baseline over time (P = 0.11) nor were

they affected by treatment (P = 0.10). In addition, no time-by-treatment interaction was observed

(P = 0.23) (TABLE 8.9).

8.1.6.14 Average Physical Comfort Net AUC

Pre-meal water intake did not affect physical comfort net AUCs (TABLE 8.10).

89

8.1.7 Discussion

Based on the present findings, drinking water 10 min before a meal may influence both food and

water intake at the subsequent meal. Firstly, subjects ate 131 kcal and 178 kcal more from pizza

after intake of 150 mL pre-meal water than 0 mL and 500 mL, reflecting that the effects of pre-

meal water intake are not based on a linear volume relationship. This effect is also likely

unrelated to changes in perceived satiety given that subjective appetite ratings immediately

before the test meal were unaffected by drinking versus not drinking water. Secondly, subjects

drank less water at the pizza meal as they drank more pre-meal water although cumulative water

intake remained higher as pre-meal water intake increased.

It remains unclear from this study why a smaller volume of water increased pizza intake while

drinking a higher volume had the same effect as not drinking any water. This implies that pre-

meal WI may not affect energy regulation in a linear volume-dependent relationship.

Mechanisms that may explain the present findings include changes in intestinal water absorption,

gastric distention and gastric emptying rate. The stomach is distended by balloon inflation using

500 mL of water, which stimulates regions of the brain that control FI and increases feelings of

fullness compared to the empty balloon condition (0 mL of water) [158]. However, subjective

appetite in the present study did not change at 135 min in response to pre-meal WI compared

with control, similar to fullness ratings (data not shown). Previous reports similarly found that

hunger and FI were unaffected in subjects who drank 0 or 500 mL of water before a meal even

though they felt fuller 30 min after drinking 500 mL. This may be due to the fact that a larger

volume of water paradoxically empties faster than a smaller volume, which suggests that an

individual would feel hungrier and eat more as they drink more pre-meal water. It is likely that

intake of a liquid distends the stomach but the activation of satiety-related mechanisms depends

on volume, time of consumption and/or the type of nutrient(s) present in the beverage based on

the opposing effects of gastric distention and emptying. The body may also distinguish between

intake of solids and non-nutritive liquids. In the present study, food intake following 500 mL of

pre-meal water was not statistically different from the amount of energy consumed after 0 mL.

Gastric stretch receptors may have been stimulated by water but the absence of nutrients 10 min

before the meal signaled other mechanisms favoring food intake. Regardless of the underlying

90

systems, a better dietary choice remains drinking water rather than sugary energy-dense drinks

that are strongly linked with positive energy balance and obesity in both children and adults.

One concern is that participants in the present study seemed to have arrived with weaker feelings

of appetite on the day they received 500 mL pre-meal water compared to 0 mL and 150 mL as

reflected by change from baseline values and net AUCs. This suggests that subjects started the

sessions at different baselines even though they reported compliance to the study protocol (data

not shown). However, subjects did not eat less after drinking 500 mL of water than 0 mL as

would be expected had they arrived feeling less hungry.

An additional point of discussion is the relationship between subjective thirst and fluid intake.

Ratings at 135 min decreased for 150 and 500 mL compared to the no water preload condition.

One confounder was that thirst ratings from 0 to 105 min were higher prior to subjects receiving

high-water, (50.7 ± 2.0 mm) compared to control (44.9 ± 1.9 mm, P = 0.04) but not to low-water

(48.0 ± 1.8 mm, P = 0.34) even though control and pre-meal water treatments consisted of the

same bean vehicles. After determining thirst ratings change from baseline, ratings at 135 min

were still lower as pre-meal water intake increased but the treatment effect disappeared. In other

words, subjects may have arrived feeling thirstier on the day they were supposed to received 500

mL of pre-meal water, yet drinking water 10 min before the meal still decreased thirst after

accounting for subjects‟ different baselines. These findings support a link between fluid intake

and subjective thirst ratings although they do not necessarily indicate that thirst ratings predict

fluid intake patterns. In this case, thirst should not have been physiologically stimulated since

subjects ate the same control treatment of beans without any added-sodium at baseline whether

or not they drank pre-meal water. Taking into account change from baseline values, one

possibility is that individuals felt less thirsty as they drank pre-meal water because of learned

associations between fluids and thirst regulation. This then prompted them to drink less water at

the meal 10 min later because their subjective thirst was sated. WI at the meal may have also

decreased because of gastric distention, which is thought to interrupt water drinking by

activating an acute thirst satiety mechanism. The notion of learned associations is supported by

the additional findings of Experiment 1, in which subjective thirst ratings remained unchanged

when subjects ate beans with added-sodium at the test meal 120 min later. Fluid intake increased

91

with higher sodium intake when the meal was served 30 min later even though thirst ratings

remained unaffected by treatment sodium content. Perhaps fluid intake causes thirst ratings to

decrease quickly but thirst is not subjectively perceived when physiologically stimulated by

consumption of a salty meal 30 to 120 min prior to a subsequent meal.

A potential underlying factor is the intake of no-added-sodium beans upon arrival (0 to 10 min

after baseline). Beans may have influenced the effects of pre-meal WI that occurred 115 min

later after subjects finished eating beans. This was done to help standardize treatment conditions

and allow subjects to start at similar levels before pre-meal WI. However, subjects were not

consistently similar in their ratings for thirst, appetite and physical comfort ratings across the

three visits during which they either received 0, 150 or 500 mL pre-meal water. On the other

hand, during that interval, subjects did not consume any food or beverage, thereby paralleling

other studies that required subjects to not eat anything for 3 hours before drinking pre-meal

water. Another key point about the present study is that subjects were instructed to drink pre-

meal water quickly (i.e. maximum of 5 min) without feeling physically uncomfortable. Other

authors allowed participants to take up to 30 min to finish drinking pre-meal water, which would

have increased variation between subjects‟ responses at the later meal. Another underlying

factor that has been overlooked is the visual presentation of per-meal water. It is unclear

whether water and other fluids were presented in sealed, opaque containers or clear glasses in

previous studies. In the present study, water was presented in clear glasses, which in hindsight

may have influenced outcomes. Also, beverage temperature may play a role in energy intake

and subjective sensations of hunger and satiety. In the present study, water was distilled and

served at standard ambient temperature.

8.1.8 Conclusion

In conclusion, the present findings are the first to suggest that drinking a small volume of water

prior to a meal increases food intake compared to a larger volume or no preload condition. It also

appears that water intake does not induce satiety as hypothesized given that subjective appetite

ratings remained unaffected immediately before eating. Within the context of weight

management, these findings disagree with conventional thinking that pre-meal water intake

92

reduces food intake compared to no water. Future studies would need to decipher the underlying

physiological mechanisms and chronic effects of water intake on food intake regulation.

93

TABLE 8.1. Exp 1: Effect of pre-meal water intake on treatment and test meal palatability1

Pre-meal water intake

(mL) Treatment pleasantness Test meal pleasantness

mm mm

C (0 mL) 38.0 ± 5.9 64.0 ± 6.2

LW (150 mL) 41.0 ± 6.0 69.0 ± 5.2

HW (500 mL) 46.4 ± 6.1 62.4 ± 5.9

P2 0.29 0.48



2 Overall P value reflects data for all five preload conditions. Overall P value reflects data for all five preload

conditions. Orthogonal contrasts were applied to compare control and pre-meal water intake treatments only.

Treatment pleasantness: C vs. LW (P = 0.89); C vs. HW (P = 0.63); LW vs. HW (P = 0.72). Test meal pleasantness:

C vs. LW (P = 0.23); C vs. HW (P = 0.59); LW vs. HW (P = 0.09).

TABLE 8.2. Exp 1: Effect of pre-meal water intake on food, sodium and water intakes1

Pre-meal water

intake

Energy intake at test

meal

Sodium intake at test

meal

Water intake

Test meal Cumulative2

kcal mg g g

C (0 mL) 1337 ± 106b 3072 ± 256

b 352 ± 33

a 352 ± 33

c

LW (150 mL) 1468 ± 89a 3361 ± 223

a 333 ± 31

a 483 ± 31

b

HW (500 mL) 1290 ± 108b 2915 ± 245

b 227 ± 36

b 727 ± 36

a

P3 0.01 0.009 0.0002 <0.0001



2 Sum of total treatment and test meal water intake.


and pre-meal water intake treatments only. Energy intake: C vs. LW (P = 0.03); C vs. HW (P = 0.40); LW vs. HW

(P = 0.004). Sodium intake: C vs. LW (P = 0.04); C vs. HW (P = 0.25); LW vs. HW (P = 0.002). Water intake: C vs.

LW (P = 0.72); C vs. HW (P = 0.0001); LW vs. HW (P = 0.0003). Cumulative water intake: C vs. LW (P <

0.0001); C vs. HW (P < 0.0001); LW vs. HW (P < 0.0001).

94

TABLE 8.3. Exp 1: Effect of pre-meal water intake on pre-meal average appetite scores1

Pre-meal water intake Time marginal

mean Time C (0 mL) LW (150 mL) HW (500 mL)

mm

Absolute ratings2

0 min 67.7 ± 3.8 68.9 ± 4.0 74.2 ± 3.8 68.7 ± 1.8

15 min 38.9 ± 4.8 37.6 ± 5.4 43.3 ± 6.0 42.5 ± 2.2

30 min 44.1 ± 4.6 41.2 ± 4.6 46.8 ± 5.8 45.3 ± 2.3

45 min 48.4 ± 4.8 48.3 ± 4.3 49.0 ± 6.0 48.8 ± 2.1

60 min 51.8 ± 4.6 50.5 ± 4.1 49.0 ± 5.6 51.3 ± 2.1

75 min 56.0 ± 4.6 54.1 ± 4.5 53.9 ± 5.2 55.3 ± 2.0

105 min 61.2 ± 4.9 58.3 ± 4.6 60.3 ± 5.2 60.4 ± 2.0

135 min 65.3 ± 5.4 64.7 ± 4.5 61.5 ± 4.4 65.1 ± 2.0

Treatment marginal

mean 54.2 ± 1.8 53.0 ± 1.8 54.8 ± 2.0 --


15 min -29.3 ± 5.5 -31.2 ± 6.3 -30.8 ± 5.7 -26.1 ± 2.5

30 min -23.6 ± 4.7 -27.7 ± 4.9 -27.3 ± 5.3 -23.4 ± 2.2

45 min -19.2 ± 4.6 -20.6 ± 4.0 -25.1 ± 4.6 -19.9 ± 1.9

60 min -15.9 ± 4.8 -18.3 ± 4.6 -25.2 ± 3.9 -17.3 ± 1.9

75 min -11.7 ± 4.3 -14.8 ± 5.1 -20.2 ± 3.2 -13.4 ± 1.8

105 min -6.5 ± 4.0 -10.6 ± 4.7 -13.9 ± 3.1 -8.3 ± 1.7

135 min -2.3 ± 5.2 -4.1 ± 3.2 -12.7 ± 3.5 -3.6 ± 1.8

Treatment marginal

mean -15.4 ± 1.9 -18.2 ± 1.9 -22.1 ± 1.7

--




effect: C vs. LW (P = 0.78); C vs. HW (P = 0.62); LW vs. HW (P = 0.45).


0.48). Treatment effect: C vs. LW (P = 0.32); C vs. HW (P = 0.008); LW vs. HW (P = 0.10).

95

TABLE 8.4. Exp 1: Effect of pre-meal water intake on pre-meal average appetite areas under

the curve (AUC)1

Pre-meal water intake Pre-meal average appetite AUC2

mmmin

C (0 mL) -1803.1 ± 512.6b

LW (150 mL) -2178.4 ± 533.7ab

HW (500 mL) -2682.8 ± 440.1a

P3 0.04

1 All values are means ± SEM; n = 16. Values at each time of measurement with different superscript letters are

significantly different, P < 0.05 (one-factor ANOVA for treatment effect followed by orthogonal contrasts).



and pre-meal water intake treatments only. Average appetite AUC: C vs. LW (P = 0.27); C vs. HW (P = 0.03); LW

vs. HW (P = 0.26).

96

TABLE 8.5. Exp 1: Effect of pre-meal water intake on pre-meal thirst ratings1


Time marginal mean Time C (0 mL) LW (150 mL) HW (500 mL)

mm

Absolute ratings2

0 min 56.3 ± 5.3 46.6 + 5.9 48.1 ± 3.7 50.6 ± 2.3ab

15 min 46.2 ± 5.6 41.8 ± 6.6 40.2 ± 6.6 42.2 ± 2.7c

30 min 45.4 ± 4.9 41.9 ± 5.8 40.4 ± 5.7 43.1 ± 2.4ab

45 min 48.6 ± 4.9 41.8 ± 5.5 41.6 ± 5.2 44.3 ± 2.3ab

60 min 50.8 ± 4.2 40.8 ± 5.4 45.9 ± 5.3 45.3 ± 2.3ab

75 min 50.1 ± 4.6 43.5 ± 5.2 45.9 ± 5.4 46.7 ± 2.2ab

105 min 54.1 ± 4.4 43.2 ± 5.5 51.8 ± 5.6 50.0 ± 2.3a

135 min 53.4 ± 5.4 35.9 ± 5.6 27.3 ± 4.9 44.1 ± 2.6bc

Treatment marginal

mean 45.1 ± 1.8 47.2 ± 1.7 49.9 ± 1.8 --


15 min -10.1 ± 5.9 -4.8 ± 5.9 -7.9 ± 5.6 -8.3 ± 2.4

30 min -10.9 ± 5.1 -4.7 ± 4.0 -7.7 ± 4.7 -7.5 ± 1.9

45 min -7.8 ± 5.2 -4.8 ± 3.7 -6.5 ± 4.2 -6.3 ± 1.9

60 min -5.5 ± 4.9 -5.8 ± 3.0 -2.2 ± 4.1 -5.2 ± 1.7

75 min -6.2 ± 5.0 -3.1 ± 3.7 -2.2 ± 4.0 -3.8 ± 1.7

105 min -2.3 ± 4.2 -3.4 ± 3.9 3.6 ± 3.8 -0.6 ± 1.8

135 min -2.9 ± 2.6a -10.7 ± 4.4

a -20.8 ± 3.3

b -6.5 ± 1.9

Treatment marginal

mean -6.5 ± 1.8 -5.3 ± 1.6 -6.2 ± 1.7

--





3 Change from baseline two-factor ANOVA. Time (P = 0.01), treatment (P = 0.80) and time x treatment (P <


97

TABLE 8.6. Exp 1: Effect of pre-meal water intake on pre-meal thirst areas under the curve

(AUC)1

Pre-meal water intake Pre-meal thirst AUC2

mmmin

C (0 mL) -765.5 ± 555.5

LW (150 mL) -632.3 ± 386.2

HW (500 mL) -591.1 ± 418.9

P3 0.95





and pre-meal water intake treatments only. Thirst AUC: C vs. LW (P = 0.48); C vs. HW (P = 0.73); LW vs. HW (P

= 0.71).

98

TABLE 8.7. Exp 1: Effect of pre-meal water intake on pre-meal blood glucose concentrations1


Time marginal mean

Time C (0 mL) LW (150 mL) HW (500 mL)

mmol/L

Absolute concentrations2

0 min 4.8 ± 0.1 4.9 ± 0.1 5.0 ± 0.1 4.9 ± 0.0d

30 min 5.7 ± 0.1 5.8 ± 0.1 5.8 ± 0.1 5.8 ± 0.1ab

45 min 5.9 ± 0.1 5.9 ± 0.1 6.0 ± 0.1 5.9 ± 0.1a

60 min 6.0 ± 0.2 5.9 ± 0.2 6.0 ± 0.1 5.9 ± 0.1a

75 min 5.7 ± 0.2 5.4 ± 0.2 5.6 ± 0.1 5.6 ± 0.1b

105 min 5.2 ± 0.2 5.2 ± 0.2 5.3 ± 0.2 5.3 ± 0.1bc

135 min 5.1 ± 0.1 5.1 ± 0.1 5.4 ± 0.1 5.2 ± 0.1cd

Treatment marginal

mean 5.5 ± 0.1 5.5 ± 0.1 5.6 ± 0.1 --

Change from 0 min concentrations3

30 min 0.8 ± 0.1 0.9 ± 0.1 0.8 ± 0.1 0.8 ± 0.1ab

45 min 1.0 ± 0.2 1.0 ± 0.1 1.0 ± 0.1 1.0 ± 0.1a

60 min 1.1 ± 0.2 1.0 ± 0.2 0.9 ± 0.1 1.0 ± 0.1a

75 min 0.9 ± 0.2 0.5 ± 0.2 0.6 ± 0.1 0.7 ± 0.1bc

105 min 0.4 ± 0.2 0.3 ± 0.2 0.3 ± 0.2 0.4 ± 0.1cd

135 min 0.2 ± 0.2 0.2 ± 0.1 0.4 ± 0.1 0.2 ± 0.1d

Treatment marginal

mean 0.7 ± 0.1 0.6 ± 0.1 0.7 ± 0.1

--







99

TABLE 8.8. Exp 1: Effect of pre-meal water intake on pre-meal blood glucose areas under the

curve (AUC)1

Pre-meal water intake Pre-meal BG AUC2

mmolmin/L

C (0 mL) 85.4 ± 20.3

LW (150 mL) 72.9 ± 12.2

HW (500 mL) 75.2 ± 12.3

P3 0.57





and pre-meal water intake treatments only. Blood glucose AUC: C vs. LW (P = 0.41); C vs. HW (P = 0.30); LW vs.

HW (P = 0.85).

100


scores1


mean Time C (0 mL) LW (150 mL) HW (500 mL)

mm

Absolute ratings2

0 min 82.6 ± 4.4 83.1 ± 4.4 81.0 ± 4.3 83.0 ± 1.7

15 min 83.8 ± 4.0 80.7 ± 5.2 82.8 ± 4.4 82.7 ± 1.9

75 min 84.5 ± 4.1 82.4 ± 4.3 85.0 ± 3.5 84.5 ± 1.7

135 min 85.2 ± 2.9 87.5 ± 2.6 82.1 ± 4.7 85.0 ± 1.6

Treatment marginal

mean 84.0 ± 1.9 83.4 ± 2.1 82.7 ± 2.1 --


15 min 1.2 ± 1.2 -2.4 ± 2.4 1.8 ± 2.8 -0.3 ± 1.0

75 min 1.9 ± 2.2 -0.8 ± 2.3 3.9 ± 1.6 1.5 ± 0.9

135 min 2.6 ± 2.5 4.4 ± 3.2 1.1 ± 2.3 1.9 ± 1.1

Treatment marginal

mean 1.9 ± 1.2 0.4 ± 1.5 2.3 ± 1.3

--







101



Pre-meal water intake Pre-meal average physical comfort AUC2

mmmin

C (0 mL) 232.9 ± 232.8

LW (150 mL) -6.3 ± 268.4

HW (500 mL) 334.6 ± 241.4

P3 0.13





and pre-meal water intake treatments only. Physical comfort AUC: C vs. LW (P = 0.35); C vs. HW (P = 0.60); LW

vs. HW (P = 0.15).

102

8.2 Appendix II: Supplementary Results for Experiment 1

8.2.1 Screening Food Frequency Questionnaire Data

TABLE 8.11. Exp 1: Screening food frequency questionnaire data1

Food item Enjoyment

(1=not at all;

10=very much)

Almost daily Weekly

(1-3x)

Monthly

(1-3x)

Never

Pasta 7.6 3 10 3 0

Rice 6.6 4 10 2 0

Potatoes (mashed, roasted) 7.3 2 8 5 1

French fries 6.1 0 7 8 1

Pizza 8.2 1 10 5 0

Bread, bagels, dinner rolls 6.6 7 6 3 0

Sandwiches and subs 6.0 6 8 2 0

Cereal 6.6 10 4 1 1

Cake, donuts, cookies 7.4 3 9 4 0

1 n = 16

8.2.2 Past 24-hour Food Intake, Physical Activity and Stress Levels

TABLE 8.12. Exp 1: Effect of sodium content of a solid food (beans) on past 24-hour food

intake, physical activity and stress levels1

Treatment added-sodium

content Food Intake Physical activity Stress

mm mm mm

C (0 mg) 43.9 ± 2.7 48.8 ± 3.2 55.1 ± 3.4

LS (740 mg) 45.1 ± 3.3 48.5 ± 1.5 47.3 ± 2.7

HS (1480 mg) 44.1 ± 2.5 45.9 ± 3.1 46.3 ± 3.2

P2 0.61 0.74 0.35




and added-sodium treatments only. Food intake: C vs. LS (P = 0.67); C vs. HS (P = 0.81); LS vs. HS (P = 0.86).

Physical activity: C vs. LS (P = 0.92); C vs. HS (P = 0.42); LS vs. HS (P = 0.36). Stress levels: C vs. LS (P = 0.10);

C vs. HS (P = 0.07); LS vs. HS (P = 0.87).

103

8.2.3 Food, Sodium and Water Intakes with Covariates


intakes with treatment pleasantness as a covariate1

Treatment added-

sodium content

Energy intake at test

meal

Sodium intake Water intake

at test meal Test meal Cumulative2

kcal mg mg g

C (0 mg) 1337 ± 106ab

3072 ± 258ab

3143 ± 258c 352 ± 33

LS (740 mg) 1420 ± 114a 3257 ± 275

a 4068 ± 274

b 338 ± 36

HS (1480 mg) 1304 ± 81b 2994 ± 200

b 4545 ± 200

a 343 ± 34

P3 0.01 0.008 < 0.0001 0.0003





and added-sodium treatments only. Energy intake: C vs. LS (P = 0.22); C vs. HS (P = 0.50); LS vs. HS (P = 0.05).

Sodium intake: C vs. LS (P = 0.24); C vs. HS (P = 0.46); LS vs. HS (P = 0.05). Cumulative sodium intake: C vs. LS

(P < 0.0001); C vs. HS (P < 0.0001); LS vs. HS (P = 0.0009). Water intake: C vs. LS (P = 0.54); C vs. HS (P =

0.62); LS vs. HS (P = 0.91).


intakes with baseline average appetite as a covariate1

Treatment added-

sodium content

Energy intake at

test meal

Sodium intake Water intake at

test meal Test meal Cumulative2

kcal mg mg g

C (0 mg) 1337 ± 106 3072 ± 258 3143 ± 258c 352 ± 33

LS (740 mg) 1420 ± 114 3257 ± 275 4068 ± 274b 338 ± 36

HS (1480 mg) 1304 ± 81 2994 ± 200 4545 ± 200a 343 ± 34

P3 0.01 0.007 < 0.0001 0.0006





and added-sodium treatments only. Energy intake: C vs. LS (P = 0.18); C vs. HS (P = 0.69); LS vs. HS (P = 0.09).

Sodium intake: C vs. LS (P = 0.19); C vs. HS (P = 0.68); LS vs. HS (P = 0.10). Cumulative sodium intake: C vs. LS

(P < 0.0001); C vs. HS (P < 0.0001); LS vs. HS (P = 0.0005). Water intake: C vs. LS (P = 0.61); C vs. HS (P =

0.79); LS vs. HS (P = 0.82).

104

8.2.4 Desire to Eat


scores at each measurement time1



mm

Absolute ratings2

0 min 65.0 ± 4.1 67.2 ± 3.9 57.6 ± 5.0 64.3 ± 2.0a

15 min 34.9 ± 5.3 46.6 ± 5.5 40.3 ± 5.2 39.7 ± 2.5d

30 min 41.8 ± 4.9 51.1 ± 5.8 38.9 ± 5.2 43.2 ± 2.4d

45 min 43.8 ± 5.6 48.3 ± 5.4 42.1 ± 4.8 45.0 ± 2.4cd

60 min 50.4 ± 4.5 54.8 ± 5.2 44.9 ± 5.2 48.9 ± 2.4bcd

75 min 52.3 ± 4.9 54.5 ± 4.8 48.5 ± 5.7 51.3 ± 2.4bcd

105 min 57.4 ± 5.8 57.4 ± 4.1 53.8 ± 5.6 56.3 ± 2.4bc

135 min 60.3 ± 6.0 64.5 ± 4.5 59.1 ± 5.2 60.5 ± 2.3ab


a 48.1 ± 1.9

b --


15 min -30.1 ± 6.8 -20.6 ± 5.1 -17.4 ± 5.8 -24.7 ± 2.7d

30 min -23.2 ± 5.1 -16.1 ± 5.1 -18.8 ± 4.5 -21.2 ± 2.2cd

45 min -21.3 ± 5.5 -18.9 ± 4.9 -15.5 ± 4.1 -19.3 ± 2.2bcd

60 min -14.6 ± 4.7 -12.4 ± 4.4 -12.7 ± 4.3 -15.5 ± 2.1bcd

75 min -12.7 ± 4.6 -12.7 ± 4.0 -9.1 ± 4.8 -13.1 ± 2.1abc

105 min -7.6 ± 5.2 -9.8 ± 3.9 -3.8 ± 5.5 -8.1 ± 2.2ab

135 min -4.8 ± 6.1 -2.7 ± 4.2 1.4 ± 4.8 -3.8 ± 2.2a








105



Added-sodium treatment content Pre-meal desire-to-eat AUC2

mmmin

C (0 mg) -1921.4 ± 598.0

LS (740 mg) -1638.3 ± 442.5

HS (1480 mg) -1248.8 ± 529.5

P3 0.26





and added-sodium treatments only. Desire-to-eat AUC: C vs. LS (P = 0.63); C vs. HS (P = 0.22); LS vs. HS (P =

0.45).

106

8.2.5 Hunger

TABLE 8.17. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal hunger scores

at each measurement time1



mm

Absolute ratings2

0 min 64.9 ± 4.1 63.9 ± 4.3 57.8 ± 4.8 63.9 ± 2.0a

15 min 31.3 ± 5.0 42.3 ± 5.8 32.1 ± 5.1 35.5 ± 2.5f

30 min 36.9 ± 4.9 44.4 ± 5.9 36.7 ± 5.1 38.9 ± 2.4ef

45 min 44.6 ± 5.3 48.1 ± 5.2 38.8 ± 5.3 43.1 ± 2.4def

60 min 48.3 ± 4.5 52.7 ± 5.3 42.9 ± 5.5 46.6 ± 2.3cde

75 min 51.6 ± 4.9 55.0 ± 4.9 48.6 ± 5.3 50.4 ± 2.3cd

105 min 57.6 ± 5.6 56.6 ± 4.2 53.5 ± 5.5 54.9 ± 2.3bc

135 min 62.1 ± 5.2 64.1 ± 4.9 60.7 ± 5.3 61.3 ± 2.2ab

Treatment marginal mean 49.6 ± 2.0ab

53.4 ± 1.9a 46.4 ± 2.0

b --


15 min -33.6 ± 5.7 -21.6 ± 6.8 -25.7 ± 5.2 -28.4 ± 2.7e

30 min -27.9 ± 5.1 -19.4 ± 6.3 -21.1 ± 4.6 -25.0 ± 2.5de

45 min -20.3 ± 5.1 -15.8 ± 4.8 -19.0 ± 5.3 -20.8 ± 2.2cde

60 min -16.6 ± 4.6 -11.2 ± 4.8 -14.9 ± 5.5 -17.3 ± 2.2bcd

75 min -13.3 ± 4.9 -8.9 ± 4.4 -9.2 ± 5.3 -13.5 ± 2.2bc

105 min -7.3 ± 4.9 -7.3 ± 4.8 -4.3 ± 5.2 -9.0 ± 2.2ab

135 min -2.8 ± 5.3 0.3 ± 4.4 2.9 ± 5.1 -2.6 ± 2.1a








107

TABLE 8.18. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal hunger areas


Added-sodium treatment content Pre-meal hunger AUC2

mmmin

C (0 mg) -2036.7 ± 535.0

LS (740 mg) -1433.4 ± 528.8

HS (1480 mg) -1499.5 ± 565.5

P3 0.24





and added-sodium treatments only. Hunger AUC: C vs. LS (P = 0.33); C vs. HS (P = 0.72); LS vs. HS (P = 0.51).

108

8.2.6 Fullness

TABLE 8.19. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal fullness scores

at each measurement time1



mm

Absolute ratings2

0 min 27.8 ± 4.0 27.3 ± 4.0 27.3 ± 4.8 23.6 ± 1.8f

15 min 58.6 ± 5.7a 45.0 ± 5.3

b 53.4 ± 5.2

ab 54.0 ± 2.5

a

30 min 52.1 ± 5.6 45.8 ± 5.7 49.8 ± 5.4 50.9 ± 2.5ab

45 min 47.3 ± 5.0 44.8 ± 4.5 44.6 ± 5.9 44.7 ± 2.4bc

60 min 46.4 ± 5.5a 36.9 ± 4.2

b 44.8 ± 5.0

ab 43.6 ± 2.2

bc

75 min 37.5 ± 4.4 36.1 ± 3.7 40.1 ± 4.4 38.3 ± 2.0cd

105 min 31.9 ± 4.7 30.4 ± 3.7 32.4 ± 5.3 32.4 ± 2.1de

135 min 27.1 ± 5.3a 21.8 ± 3.8

b 28.9 ± 5.2

a 27.8 ± 2.2

ef

Treatment marginal mean --


15 min 30.8 ± 6.5 17.7 ± 6.9 26.2 ± 6.7 30.4 ± 3.0a

30 min 24.4 ± 5.8 18.4 ± 6.9 22.6 ± 6.5 27.2 ± 2.8ab

45 min 19.5 ± 5.1 17.4 ± 5.9 17.3 ± 6.2 21.1 ± 2.7bc

60 min 18.7 ± 5.8 9.6 ± 4.1 17.6 ± 5.5 19.9 ± 2.4bc

75 min 9.8 ± 4.1 8.8 ± 3.4 12.8 ± 4.6 14.6 ± 2.1cd

105 min 4.1 ± 4.3 3.1 ± 4.0 5.2 ± 4.7 8.7 ± 2.0de

135 min -0.7 ± 5.2 -5.5 ± 2.8 1.7 ± 4.6 4.2 ± 2.0e






3 Change from baseline two-factor ANOVA. Time (P < 0.0001), treatment (P < 0.0001) and time x treatment (P =


109

TABLE 8.20. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal fullness areas


Added-sodium treatment content Pre-meal fullness AUC2

mmmin

C (0 mg) 1733.4 ± 566.9

LS (740 mg) 1155.5 ± 520.4

HS (1480 mg) 1723.6 ± 577.6

P3 0.0003





and added-sodium treatments only. Fullness AUC: C vs. LS (P = 0.26); C vs. HS (P = 0.90); LS vs. HS (P = 0.20).

110

8.2.7 Prospective Food Consumption


food intake scores at each measurement time1



mm

Absolute ratings2

0 min 68.5 ± 4.4 73.3 ± 3.9 65.9 ± 4.8 70.2 ± 2.0a

15 min 48.2 ± 5.9 57.3 ± 5.6 48.9 ± 6.2 49.1 ± 2.7c

30 min 49.6 ± 5.8 55.1 ± 6.0 48.0 ± 5.8 50.1 ± 2.6c

45 min 52.7 ± 5.6 55.8 ± 5.0 49.9 ± 5.3 51.9 ± 2.4c

60 min 54.9 ± 5.9 58.3 ± 5.5 49.9 ± 5.4 53.5 ± 2.5c

75 min 57.5 ± 5.7 61.8 ± 4.2 57.3 ± 5.2 57.6 ± 2.3bc

105 min 61.6 ± 5.2 66.7 ± 3.4 63.9 ± 4.9 62.8 ± 2.2b

135 min 65.9 ± 5.9 72.3 ± 3.5 66.2 ± 3.5 66.4 ± 2.0ab


a 56.2 ± 1.9

b --


15 min -22.2 ± 5.8 -16.0 ± 4.9 -17.0 ± 5.5 -21.0 ± 2.5c

30 min -20.0 ± 5.7 -18.2 ± 5.0 -17.9 ± 4.3 -20.0 ± 2.3c

45 min -16.8 ± 5.3 -17.5 ± 3.2 -16.0 ± 4.0 -18.3 ± 1.9c

60 min -15.0 ± 5.6 -15.1 ± 3.8 -15.9 ± 3.9 -16.7 ± 2.0c

75 min -12.4 ± 5.3 -11.5 ± 2.3 -8.6 ± 3.8 -12.5 ± 1.9bc

105 min -7.9 ± 4.0 -6.6 ± 3.1 -2.0 ± 4.0 -7.4 ± 1.8ab

135 min -3.6 ± 5.4 -1.0 ± 3.2 0.3 ± 3.9 -3.7 ± 1.8a








111


food intake areas under the curve (AUC)1

Added-sodium treatment content Pre-meal prospective food intake AUC2

mmmin

C (0 mg) -1520.6 ± 558.0

LS (740 mg) -1473.8 ± 376.6

HS (1480 mg) -1251.6 ± 450.4

P3 0.27





and added-sodium treatments only. Prospective food intake AUC: C vs. LS (P = 0.90); C vs. HS (P = 0.98); LS vs.

HS (P = 0.88).

112

8.2.8 Nausea

TABLE 8.23. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal nausea

scores1


mean Time C (0 mg) LS (740 mg) HS (1480 mg)

mm

Absolute ratings2

0 min 17.4 ± 6.8 11.6 ± 3.5 16.4 ± 5.6 15.8 ± 2.5a

15 min 14.1 ± 5.6 17.0 ± 5.6 14.2 ± 4.0 15.5 ± 2.4ab

75 min 13.1 ± 5.4 13.4 ± 4.9 12.8 ± 4.1 12.3 ± 2.0b

135 min 11.9 ± 3.9 12.9 ± 4.5 11.8 ± 4.9 12.8 ± 2.2ab



15 min -3.4 ± 3.0 5.4 ± 2.4 -2.2 ± 3.6 -0.3 ± 1.3

75 min -4.3 ± 4.6 1.8 ± 2.2 -3.6 ± 2.4 -3.5 ± 1.5

135 min -5.6 ± 5.0 1.3 ± 1.5 -4.6 ± 3.4 -3.0 ± 1.6

Treatment marginal mean -4.4 ± 2.4b 2.9 ± 1.2

a -3.5 ± 1.8

b --







113

TABLE 8.24. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal nausea areas


Added-sodium treatment content Pre-meal nausea AUC2

mmmin

C (0 mg) -525.9 ± 513.1

LS (740 mg) 357.7 ± 233.5

HS (1480 mg) -436.4 ± 353.6

P3 0.60





and added-sodium treatments only. Nausea AUC: C vs. LS (P = 0.17); C vs. HS (P = 0.85); LS vs. HS (P = 0.23).

114

8.2.9 Stomach Pain


scores1



mm

Absolute ratings2

0 min 15.6 ± 5.0 9.1 ± 2.9 17.0 ± 4.7 16.1 ± 2.3

15 min 14.4 ± 5.6 12.9 ± 3.6 12.6 ± 4.0 14.3 ± 1.9

75 min 11.8 ± 3.8 11.9 ± 3.5 10.4 ± 3.1 11.9 ± 1.6

135 min 11.3 ± 3.0 10.9 ± 3.5 10.5 ± 3.4 12.2 ± 1.8



15 min -1.2 ± 2.6 3.8 ± 2.3 -4.4 ± 4.5 -1.8 ± 1.8a

75 min -3.9 ± 2.3 2.8 ± 2.4 -6.6 ± 4.3 -4.2 ± 1.7b

135 min -4.4 ± 2.4 1.8 ± 2.3 -6.5 ± 4.1 -3.9 ± 1.5b

Treatment marginal mean -3.1 ± 1.4ab

2.8 ± 1.3a -5.8 ± 2.4

b --







115



Added-sodium treatment content Pre-meal stomach pain AUC2

mmmin

C (0 mg) -410.2 ± 268.4

LS (740 mg) 356.3 ± 279.4

HS (1480 mg) -749.5 ± 538.1

P3 0.04





and added-sodium treatments only. Stomach pain AUC: C vs. LS (P = 0.18); C vs. HS (P = 0.53); LS vs. HS (P =

0.05).

116

8.2.10 Wellness

TABLE 8.27. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal wellness

scores1



mm

Absolute ratings2

0 min 66.4 ± 5.6 66.9 ± 4.7 63.1 ± 5.4 64.1 ± 2.5

15 min 66.7 ± 5.0 67.2 ± 4.9 71.6 ± 4.7 67.4 ± 2.5

75 min 70.6 ± 4.9 69.1 ± 4.5 73.3 ± 4.5 68.9 ± 2.3

135 min 69.8 ± 4.7 72.7 ± 4.0 65.0 ± 6.3 68.6 ± 2.5



15 min 0.3 ± 4.1 0.3 ± 3.5 8.6 ± 4.5 3.3 ± 1.9

75 min 4.2 ± 4.2 2.2 ± 3.1 10.3 ± 4.8 4.8 ± 1.7

135 min 3.4 ± 3.9 5.8 ± 3.2 1.9 ± 6.5 4.5 ± 2.1








117

TABLE 8.28. Exp 1: Effect of sodium content of a solid food (beans) on pre-meal wellness areas


Added-sodium treatment content Pre-meal wellness AUC2

mmmin

C (0 mg) 366.1 ± 472.7

LS (740 mg) 317.3 ± 380.4

HS (1480 mg) 994.2 ± 572.9

P3 0.52





and added-sodium treatments only. Wellness AUC: C vs. LS (P = 0.61); C vs. HS (P = 0.13); LS vs. HS (P = 0.31).

118

8.2.11 Flatulence


scores1



mm

Absolute ratings2

0 min 11.8 ± 4.2 10.3 ± 3.9 10.3 ± 3.0 9.5 ± 1.5

15 min 10.8 ± 4.3 16.8 ± 5.7 14.3 ± 4.8 13.8 ± 2.2

75 min 13.5 ± 5.1 14.7 ± 5.1 10.1 ± 3.8 13.0 ± 2.1

135 min 12.8 ± 3.5 16.7 ± 6.2 11.8 ± 4.8 11.6 ± 1.9



15 min -1.0 ± 1.7 6.5 ± 4.0 4.1 ± 3.2 4.3 ± 1.5

75 min 1.7 ± 2.5 4.4 ± 4.2 -0.2 ± 1.7 3.4 ± 1.5

135 min 1.0 ± 2.8 6.4 ± 5.7 1.5 ± 3.0 2.1 ± 1.5








119



Added-sodium treatment content Pre-meal flatulence AUC2

mmmin

C (0 mg) 106.9 ± 251.8

LS (740 mg) 691.9 ± 556.5

HS (1480 mg) 186.1 ± 302.9

P3 0.35





and added-sodium treatments only. Flatulence AUC: C vs. LS (P = 0.25); C vs. HS (P = 0.83); LS vs. HS (P = 0.35).

120

8.2.12 Diarrhoea


scores1



mm

Absolute ratings2

0 min 8.3 ± 3.4 6.0 ± 1.9 7.9 ± 2.8 7.6 ± 1.3

15 min 8.4 ± 2.9 10.9 ± 3.9 9.8 ± 3.9 10.4 ± 1.7

75 min 9.6 ± 3.7 7.7 ± 2.9 7.8 ± 4.0 9.1 ± 1.7

135 min 7.8 ± 2.6 6.1 ± 2.3 7.7 ± 4.0 7.3 ± 1.3



15 min 0.1 ± 1.2b 4.9 ± 2.1

a 1.9 ± 1.6

ab 2.8 ± 0.9

a

75 min 1.3 ± 2.0 1.7 ± 2.1 -0.1 ± 1.7 1.6 ± 0.9ab

135 min -0.5 ± 2.2 0.1 ± 0.8 -0.2 ± 1.8 -0.3 ± 1.1b








121



Added-sodium treatment content Pre-meal diarrhoea AUC2

mmmin

C (0 mg) ±

LS (740 mg) ±

HS (1480 mg) ±

P3 0.61





and added-sodium treatments only. Diarrhoea AUC: C vs. LS (P = 0.34); C vs. HS (P = 0.90); LS vs. HS (P = 0.28).

122

8.3 Appendix III: Supplementary Results for Experiment 2

8.3.1 Screening Food Frequency Questionnaire Data

TABLE 8.33. Exp 2: Screening food frequency questionnaire data1

Food item Enjoyment

(1=not at all;

10=very much)

Almost daily Weekly

(1-3x)

Monthly

(1-3x)

Never

Pasta 7.7 3 10 4 1

Rice 7.7 6 11 1 0

Potatoes (mashed, roasted) 7.4 1 9 8 0

French fries 6.9 0 10 6 2

Pizza 8.0 1 11 5 0

Bread, bagels, dinner rolls 6.9 7 7 3 1

Sandwiches and subs 7.4 3 8 7 0

Cereal 7.2 8 6 2 2

Cake, donuts, cookies 8.2 2 9 6 1

1n = 18

8.3.2 Past 24-hour Food Intake, Physical Activity and Stress Levels

TABLE 8.34. Exp 2: Effect of sodium content of a beverage (tomato juice) on past 24-hour food

intake, physical activity and stress levels1

Treatment added-sodium

content Food Intake Physical activity Stress

mm mm mm

0 mg 43.7 ± 3.5 50.7 ± 2.7 50.1 ± 4.0

500 mg 40.2 ± 2.8 47.4 ± 3.1 49.2 ± 3.3

1000 mg 43.3 ± 3.1 50.2 ± 3.4 48.5 ± 4.3

1500 mg 47.7 ± 3.3 46.7 ± 3.9 43.2 ± 5.2

2000 mg 45.4 ± 3.7 52.2 ± 2.9 40.7 ± 4.4

P3 0.22 0.66 0.46



123

8.3.3 Food, Sodium and Water Intakes with Covariates


water intakes with average treatment palatability as a covariate1

Treatment added-

sodium content

Energy intake

at test meal

Sodium intake Water intake at test

meal Test meal Cumulative2

kcal mg mg g

0 mg 1313 ± 69 3012 ± 165 3074 ± 165e 337 ± 34

ab

500 mg 1265 ± 83 2893 ± 188 3455 ± 188d 320 ± 39

b

1000 mg 1231 ± 74 2820 ± 167 3882 ± 167c 389 ± 34

ab

1500 mg 1257 ± 75 2871 ± 172 4433 ± 172b 387 ± 31

ab

2000 mg 1249 ± 76 2857 ± 176 4919 ± 176a 397 ± 31

a

P 0.88 0.82 < 0.0001 0.03




124

8.3.4 Desire to Eat


desire-to-eat ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 70.6 ± 5.7 72.7 ± 4.5 67.9 ± 5.5 70.3 ± 6.1 74.9 ± 4.4 71.3 ± 2.3a

15 min 59.7 ± 5.8 63.6 ± 5.1 62.8 ± 4.0 59.2 ± 5.7 62.1 ± 5.1 61.5 ± 2.3b

30 min 65.8 ± 5.3 73.6 ± 3.6 67.3 ± 4.0 71.2 ± 4.7 68.9 ± 4.5 69.4 ± 2.0a

Treatment

marginal mean 65.4 ± 3.2 70.0 ± 2.6 66.0 ± 2.6 66.9 ± 3.2 68.6 ± 2.7 --


60 min 16.5 ± 2.7 14.7 ± 3.3 16.8 ± 3.9 16.9 ± 3.6 16.2 ± 3.0 16.2 ± 1.5c

75 min 20.4 ± 4.2 18.9 ± 3.4 20.9 ± 4.1 21.4 ± 4.0 25.0 ± 5.1 21.3 ± 1.8bc

90 min 26.5 ± 4.8 25.5 ± 4.6 22.3 ± 4.2 28.3 ± 5.1 25.3 ± 3.7 25.6 ± 2.0ab

105 min 26.2 ± 4.3 22.9 ± 4.2 23.8 ± 4.1 28.7 ± 4.5 28.7 ± 4.2 26.1 ± 1.9ab

120 min 29.2 ± 4.3 28.1 ± 4.1 25.5 ± 4.2 29.3 ± 4.9 30.3 ± 4.4 28.4 ± 1.9ab

150 min 30.9 ± 4.1 31.8 ± 4.9 28.5 ± 4.0 30.2 ± 4.4 32.6 ± 4.7 30.8 ± 1.9a

180 min 33.4 ± 4.7 32.9 ± 5.6 30.5 ± 4.8 30.7 ± 4.4 35.7 ± 4.8 32.6 ± 2.1a

Treatment

marginal mean 31.1 ± 1.9 31.1 ± 2.0 29.5 ± 1.9 32.1 ± 2.0 32.8 ± 1.9 --


15 min -10.9 ± 5.6 -9.1 ± 4.7 -5.2 ± 4.3 -11.1 ± 5.2 -12.8 ± 4.0 -9.8 ± 2.1b

30 min -4.8 ± 5.0 0.9 ± 2.9 -0.6 ± 4.1 0.9 ± 3.4 -5.9 ± 2.9 -1.9 ± 1.7a

Treatment

marginal mean -7.8 ± 3.7 -4.1 ± 2.9 -2.9 ± 2.9 -5.1 ± 3.2 -9.4 ± 2.5 --


60 min -49.3 ± 6.3 -58.9 ± 5.8 -50.5 ± 6.2 -54.2 ± 6.5 -52.8 ± 6.1 -53.1 ± 2.7e

75 min -45.5 ± 7.3 -54.7 ± 5.4 -46.4 ± 6.4 -49.8 ± 6.9 -43.9 ± 7.0 -48.1 ± 2.9d

90 min -39.3 ± 8.1 -48.2 ± 6.5 -45.0 ± 6.2 -42.9 ± 7.1 -43.6 ± 6.0 -43.8 ± 3.0cd

105 min -39.7 ± 6.7 -50.7 ± 6.1 -43.5 ± 6.3 -42.4 ± 6.2 -40.2 ± 6.0 -43.3 ± 2.8c

120 min -36.6 ± 7.0 -45.6 ± 5.7 -41.8 ± 5.9 -41.8 ± 7.0 -38.7 ± 6.5 -40.9 ± 2.8bc

150 min -34.9 ± 6.8 -41.8 ± 6.1 -38.8 ± 5.9 -40.9 ± 6.1 -36.3 ± 6.6 -38.6 ± 2.8ab

180 min -32.4 ± 6.9 -40.7 ± 6.2 -36.8 ± 6.4 -40.5 ± 6.8 -33.3 ± 7.0 -36.7 ± 2.9a

Treatment

marginal mean -39.7 ± 2.6 -48.7 ± 2.3 -43.3 ± 2.3 -44.7 ± 2.5 -41.3 ± 2.4 --







125


meal and cumulative desire-to-eat areas under the curve (AUC)1

Added-sodium

treatment content

Desire-to-eat AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg -199.3 ± 118.0 -5282.0 ± 908.7 -6158.0 ± 1057.2

500 mg -129.9 ± 83.7 -6460.3 ± 753.9 -6228.6 ± 963.2

1000 mg -82.1 ± 92.0 -5462.0 ± 759.8 -5590.7 ± 888.0

1500 mg -159.9 ± 93.1 -5782.9 ± 805.7 -5703.6 ± 951.7

2000 mg -236.4 ± 77.9 -5525.5 ± 824.7 -6510.4 ± 745.2

P 0.63 0.35 0.89




126

8.3.5 Hunger


hunger ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 70.1 ± 5.0 69.7 ± 4.7 70.0 ± 5.2 67.2 ± 6.4 67.6 ± 5.7 68.9 ± 2.4a

15 min 58.0 ± 5.4 63.9 ± 5.2 63.8 ± 4.0 65.0 ± 4.6 61.0 ± 4.9 62.3 ± 2.1b

30 min 67.3 ± 5.2 72.3 ± 3.7 65.9 ± 4.7 71.0 ± 4.2 68.3 ± 4.0 69.0 ± 1.9a

Treatment

marginal mean 65.1 ± 3.0 68.7 ± 2.6 66.6 ± 2.7 67.7 ± 2.9 65.6 ± 2.8 --


60 min 13.2 ± 2.5 12.2 ± 2.9 15.7 ± 3.9 12.8 ± 2.7 13.0 ± 2.5 13.4 ± 1.3d

75 min 19.7 ± 3.9 17.2 ± 3.2 16.5 ± 3.5 21.5 ± 3.8 19.3 ± 3.4 18.9 ± 1.6cd

90 min 22.7 ± 4.1 22.2 ± 4.4 20.5 ± 3.9 30.0 ± 6.2 23.1 ± 3.6 24.0 ± 2.0ac

105 min 25.4 ± 4.5 21.5 ± 4.1 21.8 ± 3.7 25.7 ± 4.1 25.9 ± 4.4 24.1 ± 1.8bc

120 min 27.1 ± 4.3 23.3 ± 4.4 25.1 ± 4.6 27.0 ± 4.4 28.2 ± 4.8 26.1 ± 2.0abc

150 min 31.2 ± 4.8 32.9 ± 5.0 26.1 ± 4.5 31.6 ± 5.2 29.9 ± 4.6 30.3 ± 2.1ab

180 min 32.2 ± 4.7 31.3 ± 5.3 29.4 ± 4.4 34.1 ± 5.2 33.2 ± 5.2 32.0 ± 2.2a

Treatment

marginal mean 29.8 ± 1.9 29.1 ± 2.0 27.6 ± 1.9 31.7 ± 2.1 30.1 ± 1.9 --


15 min -12.1 ± 4.3 -5.8 ± 3.9 -6.2 ± 3.0 -2.2 ± 4.5 -6.6 ± 6.3 -6.6 ± 2.0b

30 min -2.8 ± 4.3 2.6 ± 3.5 -4.1 ± 2.6 3.8 ± 4.1 0.7 ± 5.4 0.0 ± 1.8a

Treatment

marginal mean -7.4 ± 3.1 -1.6 ± 2.7 -5.2 ± 2.0 0.8 ± 3.1 -2.9 ± 4.1 --


60 min -54.1 ± 6.1 -60.2 ± 5.5 -50.2 ± 6.5 -58.2 ± 5.5 -55.3 ± 5.6 -55.6 ± 2.6e

75 min -47.5 ± 7.0 -55.1 ± 5.3 -49.4 ± 6.4 -49.5 ± 6.3 -49.1 ± 5.7 -50.1 ± 2.7d

90 min -44.6 ± 7.3 -50.2 ± 6.1 -45.4 ± 6.3 -41.0 ± 8.0 -45.2 ± 5.8 -45.3 ± 3.0cd

105 min -41.8 ± 7.0 -50.8 ± 5.6 -44.1 ± 6.4 -45.3 ± 5.6 -42.4 ± 6.1 -44.9 ± 2.7c

120 min -40.2 ± 7.1 -49.0 ± 5.8 -40.8 ± 6.0 -44.0 ± 6.0 -40.2 ± 6.8 -42.8 ± 2.8bc

150 min -36.1 ± 7.2 -39.4 ± 6.0 -39.8 ± 6.2 -39.4 ± 6.3 -38.4 ± 6.7 -38.6 ± 2.8ab

180 min -35.1 ± 7.2 -41.0 ± 6.3 -36.5 ± 5.8 -36.9 ± 6.2 -35.2 ± 7.3 -36.9 ± 2.9a

Treatment

marginal mean -42.8 ± 2.6 -49.4 ± 2.2 -43.7 ± 2.3 -44.9 ± 2.4 -43.7 ± 2.4 --







127


meal and cumulative hunger areas under the curve (AUC)1

Added-sodium

treatment content

Hunger AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg -201.7 ± 89.5 -5500.0 ± 870.8 -6051.3 ± 841.6

500 mg -67.5 ± 77.7 -6443.7 ± 704.4 -5923.0 ± 965.4

1000 mg -123.9 ± 61.1 -5451.7 ± 749.0 -5979.1 ± 725.5

1500 mg -4.7 ± 93.3 -5749.3 ± 692.8 -5000.1 ± 1097.2

2000 mg -93.2 ± 128.0 -5820.0 ± 813.4 -5752.9 ± 974.5

P 0.84 0.34 0.88




128

8.3.6 Fullness


fullness ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 23.9 ± 4.8 22.7 ± 4.6 26.0 ± 5.5 23.7 ± 3.9 22.4 ± 4.0 23.8 ± 2.0b

15 min 32.5 ± 4.9 34.7 ± 5.9 31.5 ± 4.2 31.7 ± 3.8 32.9 ± 4.8 32.7 ± 2.1a

30 min 28.9 ± 5.1 25.2 ± 4.6 30.0 ± 4.7 26.7 ± 3.9 24.4 ± 3.0 27.0 ± 1.9b

Treatment

marginal mean 28.5 ± 2.8 27.5 ± 3.0 29.2 ± 2.7 27.4 ± 2.2 26.6 ± 2.3 --


60 min 86.5 ± 2.4 85.0 ± 2.5 84.5 ± 3.2 84.2 ± 2.9 84.6 ± 2.8 84.9 ± 1.2a

75 min 81.2 ± 3.6 82.0 ± 3.1 78.1 ± 4.3 77.1 ± 3.4 79.3 ± 3.2 79.5 ± 1.6b

90 min 75.1 ± 4.2 73.0 ± 4.8 76.9 ± 4.1 75.3 ± 3.8 74.6 ± 3.5 75.0 ± 1.8bc

105 min 73.5 ± 3.9 72.6 ± 4.2 76.1 ± 3.4 73.8 ± 3.7 71.6 ± 3.7 73.5 ± 1.7c

120 min 69.6 ± 4.3 70.8 ± 4.1 74.4 ± 3.2 72.1 ± 4.2 70.5 ± 4.5 71.5 ± 1.8c

150 min 65.3 ± 5.0 63.8 ± 5.3 69.4 ± 3.5 65.6 ± 5.4 68.9 ± 3.9 66.6 ± 2.1cd

180 min 64.2 ± 4.8 61.9 ± 5.0 68.2 ± 3.7 64.5 ± 5.2 64.1 ± 4.8 64.6 ± 2.1d

Treatment

marginal mean 68.0 ± 2.0 66.8 ± 2.1 69.7 ± 1.8 67.4 ± 2.0 67.3 ± 1.9 --


15 min 8.6 ± 4.4 11.9 ± 5.5 5.5 ± 4.2 8.0 ± 3.3 10.5 ± 5.1 8.9 ± 2.0a

30 min 4.9 ± 3.7 2.5 ± 5.0 4.0 ± 4.1 3.0 ± 3.3 1.9 ± 2.4 3.3 ± 1.7b

Treatment

marginal mean 6.8 ± 2.9 7.2 ± 3.7 4.7 ± 2.9 5.5 ± 2.3 6.2 ± 2.9 --


60 min 57.6 ± 6.1 59.8 ± 5.9 54.5 ± 6.8 57.4 ± 5.7 60.2 ± 5.1 57.9 ± 2.6a

75 min 52.3 ± 6.5 56.8 ± 6.3 48.1 ± 7.5 50.3 ± 6.7 54.9 ± 5.3 52.5 ± 2.9b

90 min 46.2 ± 6.7 47.8 ± 6.8 46.9 ± 7.1 48.6 ± 6.3 50.3 ± 5.4 47.9 ± 2.8c

105 min 44.6 ± 6.2 47.4 ± 6.8 46.1 ± 6.7 47.1 ± 6.3 47.3 ± 5.4 46.5 ± 2.8c

120 min 40.7 ± 6.9 45.6 ± 6.8 44.4 ± 6.6 45.4 ± 6.6 46.2 ± 6.0 44.5 ± 2.9c

150 min 36.4 ± 7.0 38.6 ± 7.2 39.4 ± 6.6 38.9 ± 6.8 44.6 ± 5.4 39.6 ± 2.9de

180 min 35.3 ± 6.9 36.7 ± 7.2 38.2 ± 6.6 37.7 ± 6.3 39.7 ± 6.1 37.5 ± 2.9e

Treatment

marginal mean 44.7 ± 2.5 47.5 ± 2.6 45.3 ± 2.6 46.5 ± 2.4 49.0 ± 2.1 --





3 Change from baseline two-factor ANOVA. Pre-meal: time (P = 0.0004), treatment (P = 0.98) and time x treatment


129


meal and cumulative fullness areas under the curve (AUC)1

Added-sodium

treatment content

Fullness AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg 167.8 ± 86.4 5980.7 ± 855.4 6890.5 ± 877.3

500 mg 196.6 ± 116.8 6361.2 ± 854.4 6928.8 ± 986.7

1000 mg 112.1 ± 92.2 6093.2 ± 896.6 6805.3 ± 915.3

1500 mg 132.6 ± 67.6 6235.7 ± 807.2 6818.3 ± 867.5

2000 mg 169.3 ± 88.6 6612.2 ± 690.0 7073.7 ± 797.4

P 0.95 0.86 1.00




130

8.3.7 Prospective Food Consumption


prospective food intake ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 75.8 ± 4.1 75.3 ± 3.9 76.5 ± 3.5 76.3 ± 4.5 79.3 ± 4.3 76.6 ± 1.8a

15 min 68.6 ± 4.6 74.3 ± 3.7 69.1 ± 2.8 71.7 ± 3.9 71.1 ± 4.2 70.9 ± 1.7b

30 min 71.8 ± 4.6 76.1 ± 3.6 73.0 ± 3.4 75.5 ± 3.4 74.5 ± 3.3 74.2 ± 1.6a

Treatment

marginal mean 72.1 ± 2.5 75.2 ± 2.1 72.9 ± 1.9 74.5 ± 2.3 74.9 ± 2.3 --


60 min 17.3 ± 3.8 15.7 ± 3.2 20.2 ± 4.1 17.6 ± 3.2 16.8 ± 3.0 17.5 ± 1.5e

75 min 20.6 ± 4.0 18.3 ± 3.0 19.1 ± 3.4 22.6 ± 4.3 22.4 ± 3.1 20.6 ± 1.6de

90 min 25.2 ± 4.7 26.3 ± 4.3 25.6 ± 3.7 28.7 ± 4.8 25.9 ± 3.9 26.3 ± 1.9bcd

105 min 28.5 ± 4.8 26.0 ± 3.8 26.9 ± 4.0 25.4 ± 4.2 27.1 ± 4.2 26.8 ± 1.9cd

120 min 29.6 ± 4.7 26.6 ± 3.5 27.0 ± 3.9 27.7 ± 4.0 29.2 ± 3.9 28.0 ± 1.8c

150 min 31.7 ± 5.0 34.3 ± 4.8 32.5 ± 3.9 35.4 ± 4.6 35.5 ± 4.4 33.9 ± 2.0ab

180 min 37.7 ± 5.1 35.7 ± 4.9 33.3 ± 4.2 38.1 ± 5.1 36.1 ± 4.4 36.2 ± 2.1a

Treatment

marginal mean 32.8 ± 2.0 32.4 ± 2.0 32.2 ± 1.9 33.9 ± 2.0 33.4 ± 1.9 --


15 min -7.2 ± 3.2 -1.1 ± 3.1 -7.4 ± 2.0 -4.5 ± 2.5 -8.2 ± 2.7 -5.7 ± 1.2b

30 min -4.0 ± 3.4 0.7 ± 3.4 -3.5 ± 1.9 -0.7 ± 3.3 -4.7 ± 2.7 -2.4 ± 1.3a

Treatment

marginal mean -5.6 ± 2.3 -0.2 ± 2.3 -5.4 ± 1.4 -2.6 ± 2.0 -6.5 ± 1.9 --


60 min -54.5 ± 6.2 -60.3 ± 5.6 -52.8 ± 6.1 -57.9 ± 4.9 -57.7 ± 4.7 -56.7 ± 2.4d

75 min -51.2 ± 6.2 -57.8 ± 5.2 -53.9 ± 5.9 -52.9 ± 5.8 -52.1 ± 4.8 -53.6 ± 2.5d

90 min -46.6 ± 6.8 -49.7 ± 6.1 -47.4 ± 5.8 -46.8 ± 5.7 -48.6 ± 5.3 -47.8 ± 2.6c

105 min -43.3 ± 6.7 -50.1 ± 5.9 -46.1 ± 5.8 -50.2 ± 5.4 -47.5 ± 5.3 -47.4 ± 2.6b

120 min -42.2 ± 6.9 -49.4 ± 5.3 -46.0 ± 5.6 -47.8 ± 5.2 -45.4 ± 5.7 -46.2 ± 2.5bc

150 min -40.1 ± 6.8 -41.7 ± 6.4 -40.5 ± 5.5 -40.1 ± 5.5 -39.0 ± 5.5 -40.3 ± 2.6a

180 min -34.1 ± 6.8 -40.4 ± 6.2 -39.7 ± 5.8 -37.5 ± 5.6 -38.4 ± 5.6 -38.0 ± 2.6a

Treatment

marginal mean -44.5 ± 2.5 -49.9 ± 2.2 -46.6 ± 2.2 -47.6 ± 2.1 -47.0 ± 2.0 --





3 Change from baseline two-factor ANOVA. Pre-meal: time (P = 0.003), treatment (P = 0.46) and time x treatment


131


meal and cumulative prospective food intake areas under the curve (AUC)1

Added-sodium

treatment content

Prospective food intake AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg -138.2 ± 69.9 -5900.1 ± 864.6 -6514.3 ± 921.4

500 mg -10.3 ± 67.9 -6591.3 ± 746.8 -6484.0 ± 846.3

1000 mg -136.6 ± 42.0 -6012.2 ± 754.1 -6457.5 ± 719.3

1500 mg -73.4 ± 56.1 -6293.7 ± 684.6 -6386.1 ± 898.9

2000 mg -158.7 ± 58.9 -6229.3 ± 670.1 -6992.8 ± 867.8

P 0.50 0.63 0.94




132

8.3.8 Nausea


nausea ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 14.3 ± 5.0 8.8 ± 2.9 14.9 ± 4.2 9.8 ± 3.8 7.6 ± 2.9 11.1 ± 1.7

15 min 12.0 ± 4.2 12.2 ± 4.0 9.4 ± 2.7 12.7 ± 4.1 10.5 ± 3.5 11.4 ± 1.7

30 min 11.6 ± 4.1 12.5 ± 4.3 10.3 ± 3.5 13.7 ± 4.4 10.0 ± 3.0 11.6 ± 1.7

Treatment

marginal mean 12.6 ± 2.5 11.1 ± 2.2 11.5 ± 2.0 12.1 ± 2.3 9.4 ± 1.8 --


60 min 9.5 ± 3.0 10.2 ± 2.8 8.7 ± 2.0 10.7 ± 3.9 7.8 ± 1.9 9.4 ± 1.2

75 min 11.5 ± 4.0 9.7 ± 2.7 8.6 ± 2.2 9.1 ± 2.7 8.9 ± 2.4 9.6 ± 1.2

90 min 8.6 ± 2.6 8.2 ± 2.2 8.5 ± 2.5 8.8 ± 2.8 11.0 ± 4.1 9.0 ± 1.3

105 min 10.7 ± 3.2 9.3 ± 2.7 11.5 ± 3.8 11.3 ± 4.0 8.7 ± 2.6 10.3 ± 1.5

120 min 10.5 ± 4.3 8.6 ± 2.2 8.5 ± 2.3 10.6 ± 3.8 9.5 ± 2.6 9.5 ± 1.4

150 min 10.2 ± 3.7 8.1 ± 2.5 8.6 ± 2.5 9.1 ± 3.1 7.4 ± 1.8 8.7 ± 1.2

180 min 9.0 ± 2.6 7.8 ± 2.4 8.0 ± 2.1 8.6 ± 2.8 7.5 ± 2.0 8.2 ± 1.1

Treatment

marginal mean 10.2 ± 1.2 9.3 ± 1.0 9.1 ± 0.9 10.3 ± 1.2 8.9 ± 0.9 --


15 min -2.3 ± 2.1 3.4 ± 3.1 -5.5 ± 2.5 2.9 ± 1.7 2.6 ± 2.3 0.2 ± 1.1

30 min -2.6 ± 2.2 3.7 ± 2.6 -4.6 ± 4.2 3.9 ± 1.9 2.4 ± 2.5 0.5 ± 1.3

Treatment

marginal mean -2.4 ± 1.5 3.5 ± 2.0 -5.0 ± 2.4 3.4 ± 1.3 2.5 ± 1.7 --


60 min -2.1 ± 2.2 -2.3 ± 2.8 -1.6 ± 2.7 -3.0 ± 2.8 -2.2 ± 1.8 -2.3 ± 1.1

75 min -0.6 ± 0.8 -2.7 ± 2.9 -1.7 ± 2.7 -4.6 ± 2.3 -1.1 ± 2.0 -2.2 ± 1.0

90 min -3.1 ± 2.7 -4.3 ± 3.1 -1.8 ± 3.0 -4.9 ± 2.5 1.0 ± 3.5 -2.6 ± 1.3

105 min -0.9 ± 1.9 -3.2 ± 3.1 1.2 ± 2.8 -2.4 ± 1.8 -1.3 ± 2.2 -1.3 ± 1.1

120 min -1.2 ± 1.3 -3.9 ± 2.9 -1.8 ± 2.2 -3.2 ± 2.4 -0.5 ± 2.2 -2.1 ± 1.0

150 min -1.5 ± 1.1 -4.4 ± 3.1 -1.7 ± 1.7 -4.6 ± 2.2 -2.6 ± 1.9 -3.0 ± 0.9

180 min -2.6 ± 1.9 -4.6 ± 3.2 -2.3 ± 2.7 -5.1 ± 2.4 -2.5 ± 2.1 -3.4 ± 1.1

Treatment

marginal mean -1.7 ± 0.7 -3.6 ± 1.1 -1.4 ± 1.0 -4.0 ± 0.9 -1.3 ± 0.9 --







133


meal and cumulative nausea areas under the curve (AUC)1

Added-sodium

treatment content

Nausea AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg -52.9 ± 48.0 -222.5 ± 170.9 -700.0 ± 391.7

500 mg 78.2 ± 62.3 -497.4 ± 382.3 133.4 ± 207.6

1000 mg -115.7 ± 65.6 -196.2 ± 300.0 -990.8 ± 525.2

1500 mg 69.1 ± 37.0 -529.7 ± 272.6 142.5 ± 380.0

2000 mg 59.6 ± 51.7 -192.2 ± 252.8 243.3 ± 333.8

P 0.03 0.85 0.48




134

8.3.9 Stomach Pain


stomach pain ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 8.9 ± 3.0 10.7 ± 4.3 10.6 ± 3.5 7.4 ± 2.4 7.8 ± 2.4 9.1 ± 1.4

15 min 12.1 ± 4.0 10.1 ± 3.6 8.4 ± 2.3 9.8 ± 3.0 8.2 ± 2.4 9.7 ± 1.4

30 min 9.2 ± 2.6 9.7 ± 2.7 7.6 ± 2.3 12.8 ± 3.9 9.6 ± 2.3 9.8 ± 1.2

Treatment

marginal mean 10.1 ± 1.8 10.2 ± 2.1 8.9 ± 1.6 10.0 ± 1.8 8.5 ± 1.4 --


60 min 10.3 ± 3.3 7.9 ± 2.4 10.8 ± 2.8 11.3 ± 3.5 10.2 ± 4.1 10.1 ± 1.4

75 min 13.4 ± 4.0 9.7 ± 2.7 11.8 ± 3.5 11.3 ± 3.5 13.4 ± 4.4 11.9 ± 1.6

90 min 12.4 ± 4.4a 7.6 ± 2.6

ab 7.6 ± 2.3

b 9.8 ± 3.3

ab 11.4 ± 3.5

ab 9.7 ± 1.5

105 min 11.7 ± 4.2 8.0 ± 2.6 7.4 ± 1.9 8.6 ± 2.4 12.4 ± 4.4 9.6 ± 1.4

120 min 9.1 ± 3.2 8.7 ± 2.7 7.9 ± 2.0 9.1 ± 3.1 12.5 ± 4.3 9.5 ± 1.4

150 min 9.4 ± 2.8 7.6 ± 2.6 7.5 ± 1.9 7.1 ± 2.1 11.3 ± 3.6 8.6 ± 1.2

180 min 7.2 ± 2.1 7.4 ± 2.4 9.9 ± 2.8 7.9 ± 2.6 9.5 ± 3.1 8.3 ± 1.1

Treatment

marginal mean 10.3 ± 1.2 8.3 ± 0.9 8.8 ± 0.9 9.7 ± 1.1 11.3 ± 1.3 --


15 min 3.2 ± 3.6 -0.7 ± 2.2 -2.2 ± 2.3 2.4 ± 2.3 -0.1 ± 0.9 0.5 ± 1.1

30 min 0.2 ± 2.4 -1.0 ± 2.4 -2.9 ± 3.1 5.4 ± 2.6 1.7 ± 1.1 0.7 ± 1.1

Treatment

marginal mean 1.7 ± 2.1 -0.8 ± 1.6 -2.6 ± 1.9 3.9 ± 1.7 0.8 ± 0.7 --


60 min 1.2 ± 2.3 -1.8 ± 1.6 3.2 ± 1.6 -1.6 ± 2.2 0.6 ± 3.1 0.3 ± 1.0

75 min 3.9 ± 2.3 0.0 ± 1.6 4.2 ± 2.9 -1.6 ± 1.2 3.8 ± 3.0 2.1 ± 1.0

90 min 3.2 ± 3.4 -2.2 ± 1.0 0.0 ± 2.2 -3.1 ± 2.3 1.8 ± 2.4 -0.0 ± 1.1

105 min 2.5 ± 3.3 -1.7 ± 0.9 -0.2 ± 1.9 -4.2 ± 1.9 2.8 ± 3.3 -0.2 ± 1.1

120 min -0.1 ± 2.5 -1.0 ± 1.4 0.3 ± 1.4 -3.8 ± 1.6 2.9 ± 3.1 -0.3 ± 1.0

150 min 0.3 ± 2.1 -2.2 ± 1.0 -0.2 ± 1.1 -5.7 ± 2.5 1.7 ± 2.8 -1.2 ± 0.9

180 min -2.0 ± 1.7 -2.4 ± 1.0 2.3 ± 1.7 -4.9 ± 2.0 -0.1 ± 2.0 -1.4 ± 0.8

Treatment

marginal mean 1.3 ± 1.0 -1.6 ± 0.5 1.4 ± 0.7 -3.5 ± 0.8 1.9 ± 1.1 --







135


meal and cumulative stomach pain areas under the curve (AUC)1

Added-sodium

treatment content

Stomach pain AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg 48.2 ± 65.0 167.1 ± 316.0 236.7 ± 495.5

500 mg -17.8 ± 48.0 -208.8 ± 125.2 -401.1 ± 439.7

1000 mg -52.1 ± 57.4 163.4 ± 180.6 -311.8 ± 411.6

1500 mg 76.6 ± 50.5 -506.8 ± 227.0 388.4 ± 276.7

2000 mg 12.1 ± 17.5 245.1 ± 342.8 533.8 ± 348.1

P 0.93 0.81 0.90




136

8.3.10 Wellness


wellness ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 73.1 ± 6.4 77.1 ± 4.8 76.8 ± 4.4 75.6 ± 5.3 78.7 ± 4.2 76.3 ± 2.2

15 min 73.1 ± 6.4 76.9 ± 4.5 73.6 ± 4.8 75.3 ± 4.9 73.0 ± 5.0 74.4 ± 2.3

30 min 78.2 ± 4.5 73.5 ± 5.6 74.9 ± 4.1 77.4 ± 4.3 74.9 ± 4.5 75.8 ± 2.0

Treatment

marginal mean 74.8 ± 3.3 75.8 ± 2.8 75.1 ± 2.5 76.1 ± 2.8 75.6 ± 2.6 --


60 min 76.6 ± 4.6 77.7 ± 4.5 75.5 ± 4.1 77.1 ± 5.0 76.6 ± 4.1 76.7 ± 1.9

75 min 72.8 ± 5.8 76.5 ± 4.4 74.5 ± 4.5 79.5 ± 4.1 74.5 ± 4.5 75.6 ± 2.1

90 min 76.9 ± 5.0 77.5 ± 4.3 74.7 ± 4.3 79.2 ± 4.5 76.1 ± 4.0 76.9 ± 2.0

105 min 74.2 ± 5.9 78.0 ± 4.5 75.2 ± 4.3 78.5 ± 4.2 74.2 ± 4.2 76.0 ± 2.0

120 min 72.4 ± 6.0 75.9 ± 4.6 74.5 ± 4.3 79.4 ± 4.5 73.9 ± 4.4 75.2 ± 2.1

150 min 73.6 ± 6.1 77.9 ± 4.3 75.8 ± 4.4 79.7 ± 4.4 75.7 ± 3.7 76.5 ± 2.0

180 min 77.5 ± 5.7 78.8 ± 3.9 75.9 ± 4.2 74.4 ± 5.9 75.4 ± 3.6 75.6 ± 2.2

Treatment

marginal mean 75.3 ± 1.9 77.0 ± 1.6 75.1 ± 1.5 78.2 ± 1.6 74.7 ± 1.5 --


15 min 0.0 ± 3.8 -0.2 ± 2.3 -3.2 ± 3.3 -0.3 ± 2.5 -6.2 ± 3.7 -1.9 ± 1.4

30 min 5.2 ± 3.8 -3.6 ± 3.8 -1.9 ± 2.0 1.8 ± 2.8 -3.8 ± 2.6 -0.5 ± 1.4

Treatment

marginal mean 2.6 ± 2.7 -1.9 ± 2.2 -2.6 ± 1.9 0.7 ± 1.9 -5.0 ± 2.2 --


60 min -1.6 ± 2.4 4.3 ± 2.8 0.6 ± 1.7 -0.4 ± 2.8 1.7 ± 2.0 0.9 ± 1.1

75 min -4.2 ± 2.8 3.0 ± 3.2 -0.4 ± 2.8 2.1 ± 2.0 -0.5 ± 3.2 0.0 ± 1.3

90 min -1.3 ± 2.0 4.1 ± 2.4 -0.2 ± 2.1 1.8 ± 2.4 1.2 ± 2.8 1.1 ± 1.1

105 min -4.0 ± 2.2 4.5 ± 3.3 0.3 ± 2.7 1.1 ± 2.0 -0.8 ± 2.7 0.2 ± 1.2

120 min -5.8 ± 2.7 2.4 ± 3.3 -0.4 ±1.9 2.0 ± 2.4 -1.1 ± 2.7 -0.6 ± 1.2

150 min -4.6 ± 2.6 4.4 ± 3.4 0.9 ± 2.4 2.3 ± 2.4 0.7 ± 3.3 0.8 ± 1.3

180 min -0.7 ± 2.1 5.4 ± 3.6 1.0 ± 2.2 -3.0 ± 5.4 0.5 ± 2.5 0.6 ± 1.5

Treatment

marginal mean -3.2 ± 0.9 4.0 ± 1.2 0.3 ± 0.8 0.8 ± 1.1 0.2 ± 1.0 --







137


meal and cumulative wellness areas under the curve (AUC)1

Added-sodium

treatment content

Wellness AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg 34.7 ± 18.7 -1254.1 ± 295.7 -429.1 ± 573.6

500 mg 25.3 ± 10.5 -270.4 ± 416.0 -837.6 ± 534.3

1000 mg 16.2 ± 8.0 -670.7 ± 279.2 -1012.9 ± 385.0

1500 mg 26.4 ± 11.7 -470.9 ± 265.7 -160.7 ± 389.8

2000 mg 16.3 ± 8.0 -731.1 ± 349.1 -1560.0 ± 562.2

P 0.64 0.17 0.18




138

8.3.11 Flatulence


flatulence ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 8.9 ± 2.1 9.9 ± 2.9 14.9 ± 4.6 12.8 ± 3.8 8.4 ± 3.0 11.0 ± 1.5

15 min 13.6 ± 3.5 13.1 ± 3.5 15.8 ± 5.0 17.5 ± 5.1 13.6 ± 4.8 14.7 ± 1.9

30 min 16.1 ± 5.0 16.7 ± 3.8 12.4 ± 4.0 19.3 ± 4.7 11.7 ± 3.3 15.3 ± 1.9

Treatment

marginal mean 12.9 ± 2.2 13.2 ± 2.0 14.4 ± 2.6 16.5 ± 2.6 11.2 ± 2.2 --


60 min 15.5 ± 4.7 15.0 ± 4.1 18.8 ± 5.2 17.7 ± 5.0 17.4 ± 4.8 16.9 ± 2.1

75 min 17.3 ± 5.1 16.5 ± 4.5 14.6 ± 3.9 16.6 ± 4.2 18.6 ± 4.9 16.7 ± 2.0

90 min 13.6 ± 3.8 12.7 ± 3.9 12.3 ± 3.7 16.3 ± 4.9 16.5 ± 4.2 14.3 ± 1.8

105 min 16.0 ± 4.1 15.3 ± 4.2 11.0 ± 2.5 13.8 ± 3.9 17.7 ± 4.8 14.8 ± 1.8

120 min 16.2 ± 5.1 13.8 ± 3.9 13.6 ± 3.1 16.4 ± 4.6 15.4 ± 4.3 15.1 ± 1.9

150 min 12.6 ± 3.3 14.7 ± 4.0 11.6 ± 2.5 13.1 ± 3.8 14.6 ± 3.6 13.3 ± 1.5

180 min 12.0 ± 2.8 13.3 ± 3.7 12.7 ± 3.1 18.9 ± 6.1 9.0 ± 1.9 13.2 ± 1.7

Treatment

marginal mean 14.9 ± 1.5 14.8 ± 1.4 13.4 ± 1.3 16.5 ± 1.6 15.1 ± 1.4 -


15 min 4.7 ± 1.9 3.2 ± 2.8 0.9 ± 2.1 4.6 ± 4.6 4.8 ± 5.5 3.6 ± 1.6

30 min 7.2 ± 4.2 6.8 ± 3.2 -2.5 ± 2.8 6.4 ± 3.6 3.4 ± 4.1 4.3 ± 1.6

Treatment

marginal mean 5.9 ± 2.3 5.0 ± 2.1 -0.8 ± 1.7 5.5 ± 2.9 4.1 ± 3.3 --


60 min -0.6 ± 4.3 -1.7 ± 2.6 6.4 ± 5.6 -1.5 ± 3.3 5.7 ± 4.1 1.6 ± 1.8

75 min 0.3 ± 3.5 -0.2 ± 2.6 2.2 ± 4.5 -2.6 ± 3.3 6.8 ± 4.3 1.3 ± 1.7

90 min -2.5 ± 5.1 -4.0 ± 2.9 -0.2 ± 4.2 -2.9 ± 4.4 4.8 ± 4.2 -1.0 ± 1.9

105 min -0.1 ± 5.4 -1.5 ± 3.4 -1.4 ± 2.3 -5.4 ± 3.6 5.9 ± 4.9 -0.5 ± 1.8

120 min 0.1 ± 3.6 -2.9 ± 3.4 1.2 ± 2.7 -2.8 ± 4.1 3.6 ± 3.7 -0.2 ± 1.6

150 min -3.5 ± 4.8 -2.1 ± 3.1 -0.8 ± 3.8 -6.2 ± 4.1 2.9 ± 3.1 -1.9 ± 1.7

180 min -4.1 ± 4.2 -3.4 ± 3.4 0.3 ± 3.4 -0.3 ± 7.2 -2.7 ± 2.5 -2.1 ± 1.9

Treatment

marginal mean -1.5 ± 1.7 -2.3 ± 1.1 1.1 ± 1.5 -3.1 ± 1.6 3.9 ± 1.5 --







139


meal and cumulative flatulence areas under the curve (AUC)1

Added-sodium

treatment content

Flatulence AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg 151.1 ± 10.7 -235.0 ± 562.7 1233.3 ± 510.4

500 mg 155.5 ± 8.6 -242.0 ± 352.5 894.1 ± 552.8

1000 mg 149.9 ± 8.4 156.7 ± 453.1 -210.0 ± 532.2

1500 mg 157.7 ± 8.4 -427.1 ± 488.1 787.5 ± 589.5

2000 mg 150.3 ± 8.2 515.5 ± 448.9 1170.8 ± 755.5

P 0.45 0.25 0.09




140

8.3.12 Diarrhoea


diarrhea ratings1


Time

marginal

mean

Time

0 mg

500 mg

1000 mg

1500 mg

2000 mg

mm


0 min 4.3 ± 1.4 3.8 ± 1.3 3.8 ± 1.2 5.5 ± 2.7 7.3 ± 3.6 4.9 ± 1.0

15 min 5.9 ± 1.9 6.6 ± 2.1 8.0 ± 3.2 10.1 ± 4.3 6.5 ± 2.3 7.4 ± 1.3

30 min 8.0 ± 4.2 8.7 ± 3.8 6.9 ± 2.4 8.7 ± 2.7 7.8 ± 2.8 8.1 ± 1.4

Treatment

marginal mean 6.1 ± 1.6 6.4 ± 1.5 6.3 ± 1.4 8.1 ± 1.9 7.2 ± 1.7 --


60 min 9.0 ± 3.2 9.6 ± 4.5 8.7 ± 4.0 9.1 ± 3.4 8.6 ± 2.8 9.0 ± 1.6

75 min 8.2 ± 2.6 8.6 ± 3.7 8.4 ± 3.9 8.8 ± 3.6 9.4 ± 2.9 8.7 ± 1.5

90 min 6.6 ± 2.1 6.4 ± 1.9 5.8 ± 1.9 10.9 ± 3.8 6.9 ± 2.2 7.3 ± 1.1

105 min 7.3 ± 2.0 5.2 ± 1.5 4.2 ± 1.2 8.1 ± 2.4 8.2 ± 3.5 6.6 ± 1.0

120 min 5.5 ± 1.5 5.5 ± 1.6 5.1 ± 1.7 8.8 ± 3.5 9.4 ± 4.1 6.9 ± 1.2

150 min 5.1 ± 1.4 5.0 ± 1.4 4.3 ± 1.5 7.9 ± 2.7 8.6 ± 2.6 6.2 ± 0.9

180 min 5.2 ± 1.3 5.1 ± 1.4 4.7 ± 1.5 6.8 ± 1.9 5.2 ± 1.5 5.4 ± 0.7

Treatment

marginal mean 6.8 ± 0.9 6.8 ± 1.0 6.0 ± 0.9 8.7 ± 1.1 8.0 ± 1.0 --


15 min 1.6 ± 1.3 2.8 ± 1.2 4.2 ± 2.3 4.6 ± 4.0 -1.2 ± 1.8 2.4 ± 1.1

30 min 3.7 ± 4.0 4.9 ± 3.5 3.1 ± 1.7 3.3 ± 2.6 0.6 ± 1.2 3.1 ± 1.2

Treatment

marginal mean 2.7 ± 2.1 3.8 ± 1.8 3.6 ± 1.4 3.9 ± 2.4 -0.3 ± 1.1 --


60 min 1.0 ± 3.0 0.9 ± 0.9 1.7 ± 2.1 0.4 ± 1.9 0.8 ± 1.9 1.0 ± 0.9

75 min -0.3 ± 2.8 -0.2 ± 1.0 1.5 ± 2.2 0.1 ± 2.0 1.6 ± 2.8 0.5 ± 1.0

90 min -1.4 ± 3.2 -2.3 ± 2.3 -1.1 ± 1.6 2.2 ± 1.9 -0.9 ± 2.7 -0.7 ± 1.1

105 min -0.7 ± 3.2 -3.5 ± 2.6 -2.7 ± 1.7 -0.6 ± 1.1 0.4 ± 4.0 -1.5 ± 1.2

120 min -2.5 ± 3.1 -3.3 ± 2.6 -1.8 ± 1.5 0.1 ± 1.8 1.5 ± 4.0 -1.2 ± 1.2

150 min -2.9 ± 3.5 -3.7 ± 3.3 -2.7 ± 1.4 -0.8 ± 1.1 0.8 ± 2.2 -1.9 ± 1.1

180 min -2.8 ± 3.9 -3.7 ± 3.4 -2.3 ± 1.5 -1.9 ± 1.2 -2.6 ± 2.1 -2.7 ± 1.2

Treatment

marginal mean -1.4 ± 1.2 -2.3 ± 0.9 -1.1 ± 0.7 -0.1 ± 0.6 0.2 ± 1.1 --







141


meal and cumulative diarrhea areas under the curve (AUC)1

Added-sodium

treatment content

Diarrhoea AUC2

Pre-meal

Post-meal

Cumulative

mmmin

0 mg 151.1 ± 10.7 -212.1 ± 441.6 432.5 ± 308.0

500 mg 155.5 ± 8.6 -298.0 ± 267.7 505.3 ± 304.0

1000 mg 149.9 ± 8.4 -105.8 ± 95.8 415.7 ± 223.1

1500 mg 157.7 ± 8.4 -18.2 ± 151.3 564.5 ± 397.7

2000 mg 150.3 ± 8.2 50.9 ± 342.4 140.8 ± 507.2

P 0.45 0.80 0.80




142

8.3.13 Correlations

TABLE 8.54. Exp 2: Relationships between food intake and dependent measurements

Correlated variable R P*

Food intake at 30 min

Treatment sodium content -0.06 0.59

Test meal sodium intake 0.98 <0.0001

BG at 30 min 0.30 0.003

Pre-meal BG net AUC 0.30 0.003

Post-meal BG net AUC -0.18 0.08

SA at 30 min 0.10 0.31

Pre-meal SA net AUC 0.07 0.52

Post-meal SA net AUC -0.12 0.24

WI -0.15 0.16

Thirst at 30 min 0.13 0.20

Pre-meal thirst net AUC 0.26 0.01

Post-meal thirst net AUC -0.003 0.98

Physical comfort at 30 min -0.33 0.001

Pre-meal physical comfort net AUC -0.31 0.002

Post-meal physical comfort net AUC -0.06 0.57

Treatment palatability 0.29 0.004

Pizza palatability -0.13 0.20

BMI 0.19 0.06

Weight -0.0003 1.00

Height -0.20 0.05

Past 24 h food intake 0.001 0.99

Past 24 h stress levels -0.02 0.82

Past 24 h physical activity -0.13 0.21



*Pearson correlation coefficient, probability under the null hypothesis: r = 0, correlation is significant at P < 0.05.

143

TABLE 8.55. Exp 2: Relationships between water intake and dependent measurements


Water intake at 30 min

Treatment sodium content 0.19 0.08

Test meal sodium intake -0.15 0.14

BG at 30 min -0.01 0.93

Pre-meal BG net AUC -0.001 0.99

Post-meal BG net AUC -0.21 0.04

SA at 30 min -0.08 0.47

Pre-meal SA net AUC -0.16 0.12

Post-meal SA net AUC 0.06 0.59

Thirst at 30 min -0.12 0.26

Pre-meal thirst net AUC -0.10 0.35


Physical comfort at 30 min 0.09 0.39

Pre-meal physical comfort net AUC 0.09 0.38



Pizza palatability -0.11 0.29

BMI 0.22 0.03

Weight 0.14 0.19

Height -0.07 0.52

Past 24 h food intake -0.16 0.12

Past 24 h stress levels 0.05 0.63




*Pearson correlation coefficient, probability under the null hypothesis: r = 0, correlation is significant at p<0.05.

144

TABLE 8.56. Exp 2: Relationships between subjective average appetite and dependent

measurements


Average appetite at 30 min

Treatment sodium content 0.04 0.73

Test meal sodium intake 0.09 0.39

BG at 30 min -0.09 0.38

Pre-meal BG net AUC 0.05 0.65

Post-meal BG net AUC 0.22 0.03

Thirst at 30 min 0.12 0.27

Pre-meal thirst net AUC -0.41 <0.0001


Physical comfort at 30 min 0.35 0.0004




Pizza palatability 0.34 0.0007

BMI 0.30 0.003

Weight 0.28 0.007

Height 0.08 0.47

Past 24 h food intake -0.07 0.52






145

TABLE 8.57. Exp 2: Relationships between subjective thirst and dependent measurements


Thirst at 30 min

Treatment sodium content -0.03 0.75

Test meal sodium intake 0.13 0.21

BG at 30 min 0.06 0.59

Pre-meal BG net AUC -0.10 0.35

Post-meal BG net AUC 0.0007 0.99

Physical comfort at 30 min -0.14 0.17


Post-meal physical comfort net AUC 0.11 0.31


Pizza palatability 0.07 0.48

BMI 0.27 0.009

Weight -0.06 0.54

Height -0.35 0.0004

Past 24 h food intake 0.42 <0.0001


Past 24 h physical activity 0.20 0.06




146

8.4 Appendix VI: Sample Size Calculations

For within subject designs, the sample size equation is:

n = [(z1-α/2 + z1-β) · σ/Δ]2

From Christina Wong, MSC Thesis, 2007 [137]

α = 0.05, probability of Type 1 error

β = 0.20, probability of type II error

Z 0.975 = 1.96

Z 0.80 = 0.84

σ = 169 kcal

Δ = 150 kcal

Propose n = 10

147

8.5 Appendix V: Treatment Randomization Order

8.5.1 Experiment 1 Randomization Table

Subject Session 1 Session 2 Session 3 Session 4 Session 5

1 HW LS HS LW C

2 LW HW C HS LS

3 HS C LW LS HW

4 HW LW HS C LS

5 LS C HW LW HS

6 HS HW LS C LW

7 C LW HS LS HW

8 LS HS C HW LW

9 C LS HW HS LW

10 HW C LW HS LS

11 HS HW LS LW C

12 LS HS C LW HW

13 LS C LW HW HS

14 C LW HS LS HW

15 HS LS C HW LW

16 LW C HS HW LS

C – control; LS – 740 mg added-sodium beans; HS – 1480 mg added-sodium beans; LW – 150

mL pre-meal water; HW – 500 mL pre-meal water

8.5.2 Experiment 2 Randomization Table

Subject Session 1 Session 2 Session 3 Session 4 Session 5

1 C S2000 S1000 S0500 S1500

2 S1500 S1000 S0500 C S2000

3 S2000 C S1500 S0500 S1000

4 S1000 S2000 C S1500 S0500

5 S0500 S1000 S1500 S2000 C

6 C S1500 S2000 S1000 S0500

7 S2000 S0500 S1000 S1500 C

8 S1000 C S1500 S0500 S2000

9 S2000 S1000 C S0500 S1500

10 S1500 S1000 S2000 C S0500

11 S0500 S2000 S1500 C S1000

12 C S2000 S1000 S1500 S0500

13 S1500 S0500 C S1000 S2000

14 S1000 S1500 S2000 S0500 C

15 S1000 S1500 S0500 S2000 C

16 S1500 C S0500 S1000 S2000

17 C S0500 S1000 S2000 S1500

18 S0500 S1500 C S2000 S1000

19 S2000 C S0500 S1000 S1500

C – control; S500 – 500 mg added-sodium; S1000 – 1000 mg added-sodium; S1500 – 1500 mg

added-sodium; S2000 – 2000 mg added-sodium

148

8.6 Appendix VI: Experiment 2 Treatment Recipe

Tomato Juice Recipe

Makes 1 serving (approx. 340 mL)

Ingredients

- 108 mL (4.32 oz or 122.47 g) no salt added tomato paste = 72 kcal, 54 mg sodium - 238 mL water - ½ tsp. lemon juice - ⅜ tsp. garlic and herb seasoning - ⅛ tsp. Worcestershire sauce (< 1 kcal, 6.88 mg sodium) - 3 drops Tabasco (0 kcal, 1.25 mg sodium)

Instructions

Mix all ingredients in a glass and serve chilled. Ingredient information

- Lea & Perrins (R) Worcestershire Sauce (284 ml) o Prepared for HJ Heinz Company of Canada Ltd. Product of England o 90 Sheppard Avenue East, suite 400, North York, ON, M2N 7K5 o Ingredients: malt vinegar (from barley), spirit vinegar, water, refiner’s molasses, sugar,

salt, anchovies, tamarind extract, onions, garlic, spices, and natural flavour

- McIlhenny Co. Tabasco (R) Brand Pepper Sauce (142 ml) o Made of vinegar, red pepper, and salt o Avery Island, LA, Made in USA

- Hunt’s Tomato Paste – Original (369 ml)

o Ingredients: tomatoes o Prepared under license for ConAgra Foods Canada Inc., ConAgra Canada Inc.,

Mississauga, Ontario, Canada L4V 1W5

- ReaLemon (R) Lemon Juice from concentrate (125 ml) o Ingredients: water, concentrated lemon juice, sulphites, lemon oil o Product of USA o Trademark of: Cadbury Beverages Delaware Inc. o Authorised User Cadbury Beverages Canada Inc. Cadbury Canada Inc., Mississauga,

Ontario, L5R 3L7

- McCormick (R) No Salt Added Garlic & Herb Seasoning (77 g) o Ingredients: dehydrated vegetables (garlic, onion, parsley, celery), spice (including red

pepper), dried orange peel o Imported by: McCormick Canada London, Canada N6A 4Z2

149

8.7 Appendix VII: Pizza Nutritional Composition

McCain® Deep n‟ Delicious® McCain® Deep n‟ Delicious® McCain® Deep n‟ Delicious®

Pepperoni Mini Pizza Deluxe Mini Pizza 3-Cheese Mini Pizza

150

8.8 Appendix VIII: Experiment 1 Consent Form

Effect of Potato and Beans on Glycemic Response, Appetite, and Food Intake

in Young Men

Information sheet and Consent Form

Investigators: Christina Wong, MSc Candidate

Department of Nutritional Sciences, University of Toronto

Phone: (416) 946-8276

Email: [email protected]

Dr. G. Harvey Anderson, PhD

Primary Investigator, Department of Nutritional Sciences, U of T

Phone: (416) 978-1832


Funding Source:

Part of the funding for this project is provided as a donation by the H. J. Heinz Company to Dr.

G. H. Anderson, who is a consultant to the company. Other sources of funding are from the

Ontario Ministry of Agriculture and Food under its New Directions Research Program and, the

Saskatchewan Agriculture, Food, and Rural Revitalization. The project has been peer-reviewed

and approved for its scientific merits.

Background and Purpose of Research:

Obesity is a common problem. It is important to find food based solutions for the overweight and

obesity. The data obtained from this study will be used to recommend processing strategies to

improve the health benefits and utilization of whole pulses (bean, lentil, pea, and chickpea) and

their fractions (protein and fibre) in the human diet. The objective of this research project is to

determine the effect of consuming a preload of whole pulses and their fractions (protein and

fibre) on blood glucose response, appetite and food intake. The treatments will consist of

commercially canned whole pulses and their fractions incorporated into a food matrix (e.g.

bread). Blood samples will be taken by finger prick at time zero before the consumption of the

test food products and then at 15, 30, 45, 60, 90 and 120 min. The subject‟s appetite will be

evaluated at various time points using a visual analog questionnaire. A pizza lunch will be served

at 120 min and the amount of food eaten will be recorded.

Invitation to Participate:

You are being invited to participate in this study. If you chose so, you will be given six types of

foods (listed in the previous section) on six occasions approximately one week apart. Your

151

appetite and food intake after consuming the foods will be measured. Each session will require

approximately two and a half hours of your time.

Eligibility:

To participate in this study you must be healthy and between the ages of 18 and 35. You must be

a nonsmoker and you cannot be taking any medications. The study will take place in the

Department of Nutritional Sciences, Rm 306, 334, 331 and 331A, FitzGerald Building, 150

College Street, Toronto, ON.

Procedure:

You are asked to attend six study sessions. At each session you will be asked to consume a test

food, and at six times during the study, to obtain by finger prick a drop of your blood for glucose

testing and to complete questionnaires at time outlined in the table below. You will be given a

pizza meal two hours after consuming the test food. You will be asked to adhere to your typical

routine, including exercise and to eat a similar meal the night before each session. After an

overnight fast for 12 hours except for water you will be asked to come to the lab between 8:00

and 11:00 a.m. for the study. Water may be consumed up to one hour before the session. Eight

times during each session, for a total of 48 times in the study, you will be asked to provide a drop

of blood by finger prick and to complete questionnaires measuring your appetite. The detailed

procedure for each session is summarized below in an example of a session schedule for a 9.00

a.m. arrival.

Time and Activity Schedule for Each Session

Time Activity

9:00 Arrive in the lab

9:05 Fill in Sleep, Stress, and VAS Questionnaires and take baseline blood

sample

9:10 – 9:20 Consumption of treatment

9:20 – 11:20 Blood sampling and VAS every 15 min for 1 hour and then 30 min

for the second hour

11:20 Pizza served

10 min later Take blood sample and complete VAS

Voluntary Participation and Early Withdrawal:

It is hoped that you will complete all six sessions. However, you may choose to withdraw any

time without prejudice.

Early Termination:

Not applicable

152

Risks:

All of the foods and beverages (water) that you will be asked to consume are prepared

hygienically in the kitchen or purchased from the grocery store and present no risk.

The risks and discomfort for you will come from the blood sampling procedure. Great care needs

to be taken in obtaining your finger prick blood samples. You can do your own finger pricks, or

have the investigator assist you. To avoid the possibility of two people being exposed to the

same needle, we will ask you to sit apart from each other study participants and put your own

lancet into the finger prick gun before taking each blood sample and then discard it immediately

in the safety container provided to you. It is very important that you comply with the following

precautions.

Sit a distance apart from other participant.

Use your own finger prick gun for each test and never share with anyone else.

Swab your finger with alcohol before and after each finger prick and use a new sterile

needle each time.

Immediately dispose of needles in the safety container provided.

Some discomfort will be felt as a result of a sharp momentary pain caused as the needle

penetrates the skin. However, because the lancet needle is very small the pain felt is usually less

than you might experience from skin puncture during vaccination or if a blood sample is taken

by a needle inserted in a vein.

Benefits:

You will not benefit directly from participating in this study. You will be shown your blood

glucose results and if they are abnormal you will be notified and will be advised to seek advice

from your doctor. The foods and drinks (water) will be provided free of charge.

Confidentiality and Privacy:

Confidentiality will be respected and no information that discloses the identity of the subjects

will be released or published without consent unless required by law. Your name, medical

history and signed consent form will be kept in a locked filing cabinet in the investigator‟s

office. Your results will not be kept in the same place as your name. Your results will be

recorded on data sheets and in computer records that have a code number, but not your name for

identification. Your results, identified only by an ID number, will be made available to the study

sponsor if requested.

Publication of Results:

153

The results of the study may be presented at scientific meetings and published in a scientific

journal. If the results are published, only average and not individual values of the subjects will

be reported.

Possible Commercialization of Findings:

It the desirable results are obtained, it may lead to commercialization of a product; research

subjects will not share in any way from the possible gains or profits made by commercial

application of findings.

Alternative Treatment/ Therapy:

Not applicable.

New Findings:

If anything comes to light during the course of this research which may influence your decision

to continue, you will be notified.

Compensation:

You will be paid $25 per session. If you withdraw from the study before completion or asked to

withdraw, you will be paid on the basis of the sessions already completed.

Injury Statement:

Not applicable

Rights of Subjects:

Before agreeing to participate in this research study, it is important that you read and understand

your role as described here in this study information sheet and consent form. You waive no legal

rights by participating in this study. If you have any questions or concerns about your rights as a

subject you can contact Dr. Rachel Zand, Director, Ethics Review Office, 416-946-3389.

If you have any questions after you read through this information please do not hesitate to ask

the investigators for further clarification.

Dissemination of findings:

A summary of results will be made available to you to pick up after the study is completed.

Copy of informed consent for participant:

You are given a copy of this informed consent to keep for your own records.

154

Consent:

I acknowledge that the research study described above has been explained to me and that

any questions that I have asked have been answered to my satisfaction. I have been informed of

the alternatives to participation in this study, including the right not to participate and the right to

withdraw. As well, the potential risks, harms and discomforts have been explained to me and I

also understand that there is no direct benefit to me of participating in the research study.

As part of my participation in this study, I understand that I may come in contact with

certain confidential information. I agree to keep the confidentiality of such, if any, information

unless it is necessary to disclose it to my health care provider(s), or to my legal representative(s).

I hereby agree and give my authorized consent to participate in the study and to treat

confidential information in a restrictive manner as described above. I have been given a copy of

the consent form to keep for my own records.

___________________ ___________________ _____________

Participant Name Signature Date

___________________ ___________________ _____________

Witness Name Signature Date

___________________ ___________________ _____________

Investigator Name Signature Date

155

8.9 Appendix IX: Experiment 2 Consent Form

The Effect of Different Doses of Sodium on Glycemic

Response, Subjective Appetite and Acute Food Intake in

Young Men

Information Sheet and Consent Form

Investigators: Dr. G. Harvey Anderson, Professor


Phone: (416) 978-1832


Dr. Bohdan Luhovyy, Research Associate


Phone: (416) 978-6894


Dr. Rebecca C. Mollard, Postdoctoral Fellow


Phone: (416) 978-6894


Maria Fernanda Nunez, M.Sc. candidate


Phone: (416) 978-6894


Funding Source:

Funding for this project is provided by Heinz Canada.

Background and Purpose of Research:

In 2004, almost 60% of adult Canadians were overweight or obese. This is a serious health

problem because obesity and being overweight are related to many risk factors of disease,

including increased blood sugar.

Excess body weight is a result of an energy imbalance, which can be caused by overeating.

Therefore, overweight and obesity can be treated by changing what we eat. High sodium (salt)

and high calorie convenience foods are often blamed for the current rates of obesity.

mailto:[email protected]

156

The information obtained from this study will be used to better understand the effects of sodium

on the health of young men and may lead to future studies in other groups, including women.

The purpose of this research project is to determine the effect different amounts of sodium on

blood sugar, insulin, appetite and food intake in young men.

This study will have 26 participants.

Invitation to Participate:

You are being invited to take part in this study. If you choose to take part, you will be asked to

drink a tomato juice treatment five times (five sessions) one week apart. Four of the treatments

will be juice containing sodium and one will be juice without sodium. Your appetite, blood sugar

and insulin will be measured after eating the treatment and a pizza lunch. Each session will take

up to 3 ½ hours of your time.

Eligibility:

To participate in this study you must be healthy male and between the ages of 20-30. You must

be a nonsmoker and you cannot be taking any medications. The study will take place in the

Department of Nutritional Sciences, Rm 305, 334, 331 and 331A, FitzGerald Building, 150

College Street, Toronto, ON.

Procedure:

To find out if you can take part in this study, you will be asked to fill out questionnaires, which

ask questions about your age, if you smoke, exercise, your health, if you are on any medications

and your eating habits. You height and weight will be measured.

If you can take part, you will be asked to fill out questionnaires about the foods you like. You

will be scheduled to meet with us for five sessions over five weeks.

You will be asked to eat a standard breakfast on the day of the session following a 10 hour fast

(no eating for 10 hours before eating breakfast). We will give you the standard breakfast (cereal,

milk, orange juice and a bottle of water) the day before the session.

You will be asked to arrive at the FitzGerald Building between 9:45 a.m. and 12:45 p.m., 3 ¾

hours after eating breakfast. Please do not eat between breakfast and meeting with us. You will

be asked to stick to your normal routine, including exercise and to eat a similar meal the night

before each session. You can drink water up to one hour before meeting with us.

At each session you will be asked to drink a tomato juice treatment (340 ml), give blood samples

and to complete questionnaires at the times outlined in the table below. Ten times during each

session, for a total of 50 times over the whole study, you will be asked to provide a blood by

finger prick. Blood will be sampled before eating the treatment and at 15, 30, 50, 65, 80, 95,

157

110, 140 and 170 minutes after eating the treatment. You will be asked to fill out visual analog

scale (VAS) questionnaires measuring your appetite, physical comfort and energy/fatigue as well

as the palatability (pleasantness) of the treatment and pizza throughout the study sessions. You

will be served a pizza meal 30 minutes after you eat the treatment. Each session will last up to

3.5 hours.

Time and Activity Schedule for Each Session

Time Activity

7:00 Consumption of breakfast

10:45 Arrive at the laboratory

10:50 Fill in Sleep, Stress, and VAS questionnaires and take first blood

sample

11:00 – 11:05 Eat the treatment (-5 minutes)

11:05-11:35 Blood sampling and VAS questionnaires at 15 and 30 minutes

11:35-11:55 Pizza served and eaten (30 minutes)

11:55-1:55 Blood sampling and VAS questionnaires at 50, 65, 80, 95, 110, 140

and 170 minutes

VAS: Visual analogue scale

Voluntary Participation and Early Withdrawal:

It is hoped that you will finish all five sessions. However, you may choose to stop being in the

study at anytime without any problems.

Early Termination:

Not applicable

Risks:

All of the foods and beverages that you will be asked to consume are prepared hygienically in

the kitchen and present minimal risk. Following the overnight fast you may feel dizzy, but this is

rare. If this happens, you will be fine once you eat the breakfast provided to you.

The risks and discomfort will come from the blood sampling procedure. Great care will be taken

when taking your finger prick blood samples. The investigator will help you. To make sure that

you are not exposed to another person‟s needle, we will ask you to sit away from other study

participants. We will put a needle into the finger prick gun before taking each blood sample and

then put it into the safety container. We will swab your finger with alcohol before and after each

finger prick and will use a new sterile needle each time. You will be provided with your own

finger prick gun for the entire study.

Some discomfort will be felt as a result of a sharp momentary pain caused as the needle enters

the skin. However, because the lancet needle is very small the pain felt is usually less than you

might feel from skin puncture during vaccination or if a blood sample is taken by a needle

inserted in a vein.

158

A total of 10 finger pricks will be conducted per session and may result in some discomfort.

There is very little risk of infection. Before the finger is pricked the area is cleaned with an

alcohol swab. There might be slight bruising under the skin, but this will be minimized by

applying pressure after the finger is pricked and blood sugar is measured.

Benefits:

You will not benefit directly from taking part in this study. You will be shown your blood sugar

results and if they are not normal you will be told and advised to talk to your doctor. The foods

and drinks will be provided for free.

Confidentiality and Privacy:

Confidentiality will be respected and no information that shows your identity will be released or

published without your permission unless required by law. Your name, personal information and

signed consent form will be kept in a locked filing cabinet in the investigator‟s office. Your

results will not be kept in the same place as your name. Your results will be recorded on data

sheets and in computer records that have an ID number for identification, but will not include

your name. Your results, identified only by an ID number, will be made available to the study

sponsor if requested. Only study investigators will have access to your individual results.

Publication of Results:

The results of the study may be presented at scientific meetings and published in a scientific

journal. If the results are published, only average and not individual values will be reported.

Possible Commercialization of Findings:

This study is preliminary. Once these products are tested more widely in future studies, results

may lead to commercialization of a product, new product formulation, changes in the labeling of

a product and/or changes in the marketing of a product; you will not share in any way from the

possible gains or money made by commercial application of findings.

Alternative Treatment/ Therapy:

Not applicable.

New Findings:

If anything is found during the course of this research which may change your decision to

continue, you will be told about it.

Compensation:

159

You will be paid $30 per session. You will also be given $6 per session for travel (bus, subway).

If you withdraw from the study before finishing or asked to withdraw, you will be paid for the

sessions you have already finished.

Injury Statement:

Not applicable

Rights of Subjects:

Before agreeing to take part in this research study, it is important that you read and understand

your role as described here in this study information sheet and consent form. You waive no legal

rights by taking part in this study. If you have any questions or concerns about your rights as a

participant you can contact the Ethics Review Office at [email protected] or call 416-

946-3273.

If you have any questions after you read through this information please do not hesitate to ask

the investigators for further clarification.

Dissemination of findings:

A summary of results will be made available to you to pick up after the study is done

Copy of informed consent for participant:

You are given a copy of this informed consent to keep for your own records.

Consent:

I acknowledge that the research study described above has been explained to me and that any

questions that I have asked have been answered to my satisfaction. I have been informed of the

alternatives to participation in this study, including the right not to participate and the right to

withdraw. As well, the potential risks, harms and discomforts have been explained to me. I

understand that I will receive compensation for my time spent participating in the study.

As part of my participation in this study, I understand that I may come in contact with other

study participants because our session times overlap. I agree to keep anything I learn about other

participants confidential and know that other participants have agreed to do the same for me.

I hereby agree and give my authorized consent to participate in the study and to treat confidential

information in a restrictive manner as described above. I have been given a copy of the consent

form to keep for my own records.

___________________ ___________________ _____________

Participant Name Signature Date

mailto:[email protected]

160

___________________ ___________________ _____________

Witness Name Signature Date

___________________ ___________________ _____________

Investigator Name Signature Date

161

8.10 Appendix X: Screening Questionnaire

8.10.1 Recruitment Screening Questionnaire

162

8.10.2 Sleep Habits Questionnaire

163

8.10.3 Eating Habits Questionnaire

164

8.10.4 Food Acceptability Questionnaire

165

8.10.5 Recruitment Advertising

166

8.11 Appendix XI: Study Day Session Forms

8.11.1 Sleep Habits and Stress Questionnaire

167

8.11.2 Recent Food Intake and Activity Questionnaire

168

8.11.3 Motivation to Eat VAS

169

8.11.4 Physical Comfort VAS

170

8.11.5 Energy and Fatigue VAS

171

8.11.6 Treatment/Test Meal Palatability

172

8.11.7 Test Meal Record

173

8.11.8 Blood Glucose Record

Subject ID: _____ Treatment: ______________

Date/Time: _________________

Session #: __________________

Monitor: ___________________

Standards: high ________ low ________

Blood Glucose Measurement

the effects of acute sodium ingestion on food and water ......research project in my final...

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