chapter 3 and 4

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Nutrition: Concepts & Controversies, 13th edition, Sizer & Whitney

The digestive System The Carbohydrates

Chapter 3 and 4


The Digestive System

Digestive tract Flexible, muscular tube Total length of about 26 feet Systems job is to digest food to its

components, absorb, and excrete


The Digestive System

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Carbohydrates

Ideal nutrients Energy needs Feed brain and nervous system Min: 130 grams carbs/ rec: 300 grams Keep digestive system fit Keep your body lean

Digestible and indigestible carbohydrates Complex vs. simple carbohydrates


A Close Look at Carbohydrates - Sugars

Six sugar molecules Monosaccharides

Glucose, fructose, galactose Disaccharides

Lactose, maltose, and sucrose Digestion of mono- and disaccharides

Chemical names end in -ose


How Monosaccharides Join to Form Disaccharides

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A Close Look at Carbohydrates Starch and Glycogen

Starch Plants storage form of glucose

Glycogen Storage form of glucose

Fiber


The Need for Carbohydrates

Critical energy source Nerve cells, red blood cells, and brain

Preferred dietary sources Starchy whole foods

Complex carbohydrates Vital roles in the functioning body


The Need for Carbohydrates

Weight loss Caloric contribution

Conversion into fat Refined sugars

Increase fiber-rich whole foods

Reduce refined white flour and added sugars

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Why Do Nutrition Experts Recommend Fiber-Rich Foods?

Health benefits Reduced risk of heart disease Reduced risk of diabetes Reduced risk of bowel disease Promotion of healthy body weight

Sources of fiber


Characteristics, Sources, and Health Effects of Fibers


Fiber Composition of Common Foods

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Lower cholesterol and heart disease risk Complex carbohydrates

Soluble fiber

Blood glucose control Soluble fibers

More than just fiber.


One Way Fiber in Food May Lower Cholesterol in the Blood



Maintenance of digestive tract health All kinds of fiber Ample fluid intake Benefits of fiber

Constipation, hemorrhoids, appendicitis, diverticulosis

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Digestive tract cancers Research findings about intakes Recommended dietary sources Supplements Other lifestyle factors

Healthy weight management Appetite control Less energy per bite


Fiber Recommendations and Intakes

Few people in U.S. meet recommendations 14 grams per 1,000 calories

DV-25 grams Too much fiber?

Dangers of excess-dehydration, chelating agents

Binders in fiber Chelating agents-limit absorption of

nutrients (ie, iron)


Usefulness of Carbohydrates

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Whole Grains

USDA food patterns At least half of daily grains should be

whole Four parts to the kernel

Germ Endosperm Bran husk


A Wheat Plant and a Single Kernel of Wheat


Whole Grains

U.S. Enrichment Act of 1942 Required additives

Addition in 1996 Advantages of

whole grains vs. enriched grains

Health effects of whole grains

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Nutrients in Whole-Grain, Enriched White, and Unenriched White Breads


Finding the Real Whole-Grain Foods

Not every choice must be 100% whole grain

Label readers High fiber Brown color Subtleties

Cereals


Bread Labels Compared

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Why Do Some People Have Trouble Digesting Milk?

Ability to digest milk carbohydrates varies Lactase

Made by small intestine Symptoms of intolerance

Nausea, pain, diarrhea, and gas Milk allergy Nutritional consequences


Lactose Intolerance Strategies


Splitting Glucose for Energy

Glucose can be converted to fat Fat cannot be converted to glucose Dependence on protein when insufficient

carbohydrate Protein-sparing action

Ketosis Shift in bodys metabolism

Disruption of acid-base balance DRI minimum of digestible carbohydrate

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How Is Glucose Regulated in the Body?

Two safeguard activities Siphoning off excess blood glucose Replenishing diminished glucose

Two hormones Insulin

Signals body tissues to take up glucose Glucagon

Triggers breakdown of glycogen


Blood Glucose

Regulation


Glycemic Index of Selected Foods

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Finding Carbohydrates in Foods

Fruits Vary in water, fiber, & sugar

concentrations Juice

Vegetables Grains

Low-fat and low-sugar choices


Finding Carbohydrates in Foods

Protein foods Nuts and legumes

Milk and milk products High-quality protein

Oils, solid fats, & added sugars Naturally occurring vs. added sugars Honey


Are Added Sugars Bad for You?

Controversy 4

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Do Added Sugars Cause Obesity?

Americans are fatter Greater

consumption of calories

Reduction in physical activity


Do Added Sugars Cause Obesity?

Intake of added sugars Daily intake Most sugars in

the U.S. diet are added

Carbohydrates or calories? Impact of wealth


Do Added Sugars Cause Diabetes?

Obesity and diabetes Refined carbohydrates and diabetes

Native Americans Whole foods Diabetes

Added sugars and daily caloric needs

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Do Liquid Calories Pose Special Risks?

Appetite control Peoples

expectations Gulping vs. chewing


High-Fructose Corn Syrup (HCFS)

Half of added sugar in U.S. food supply HCFS more harmful than sucrose?

Research is mixed Intakes of added sweeteners are too high

chapter 3 and 4

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