The Carbohydrates

SugarsStarches

Fiber

Objectives

• After reading Chapter 3 and class discussion, you will be able to:– Describe the functions of CHO– Identify the classification of CHO– Describe CHO digestion & absorption– Identify food sources of CHO– Calculate calories from CHO

Objectives

• Differentiate between soluble and insoluble fiber

• Identify foods that are a significant source of fiber

• Discuss health related effects of CHO in– Diabetes -Heart Disease– Obesity -GI -Cancer

4

Photosynthesis

• Plants make their own carbohydrates from – carbon dioxide in air – water from the soil

• Photosynthesis converts energy from sunlight into energy stored in carbohydrates

5

Categories of Carbohydrate

• Simple carbohydrates – Natural sugars– Added (Refined)

sugars• Complex

carbohydrates (polysaccharides)– Starch– Fiber

Carbohydrates

• Simple carbohydrates–Monosacchares–Disaccharides

• Complex carbohydrates– Glycogen– Starches– Fibers

Glucose

Fructose & Galactose

p. 84

9

Monosaccharides and Disaccharides

p. 84

Disaccharides• Maltose

– Glucose + glucose– Starch breakdown; fermentation– Barley

• Sucrose– Glucose + fructose– Table sugar from sugarcane, sugar beet

• Lactose– Gucose + galactose– Milk

Complex Carbohydrates

• Polysaccharides– Glycogen

•Storage form of glucose•Stored in liver and muscles

– Starches•Long chains of glucose linked together•Straight or branched chains

– Fibers•Soluble or viscous•Insoluble or nonviscous

Complex CarbohydratesChemical Structure

p. 91

Fig 3-6

13

Complex Carbohydrate: Starch

• Amylose - straight glucose chain• Amylopectin – branched glucose

chain• Found only in plant foods: grains,

legumes, vegetables, some fruits.• Gelatinization – When starches are

heated, they absorb water and swell in size.

Complex Carbohydrates

• Fibers– Cellulose– Hemicelluloses– Pectins– Legnin– Gums and muscilages– Resistant starches

p. 92-98

Complex Carbohydrates

• Fibers– Soluble fibers-dissolve in water

•Viscous-form gels•Fermentable-digested in colon by bacteria

Complex Carbohydrates

• Fibers– Insoluble fibers

•Nonviscous•Fermented less readily

• Phytic acid-binds minerals

Carbohydrate Categories

• Sugars• Starches• Fibers

OR

• Simple• Complex

Carbohydrate Categories

• Monosaccharide– Glucose -Fructose -Galactose

• Disaccharide– Maltose -Sucrose -Lactose

• Polysaccharide– Glycogen -Starches -Fibers

20

Functions of Carbohydrate• Primary source of body’s energy

– Central nervous system and red blood cells rely almost exclusively on glucose.

– Glucose stored in liver & muscles as glycogen.

• Protein sparing– Prevents breakdown of protein for energy

(gluconeogenesis)• Prevents ketone bodies & ketosis

– Breakdown of fat for energy

Digestion• Mouth

– Salivary amylase– Mechanical mixing; chewing

• Stomach– Continued mixing of bolus– Fibers and satiety

• Small intestine– Maltase, Sucrase, Lactase

Digestion• Pancreas

– Pancreatic amylase

• Large intestine – Colon– Fermentation of viscous fibers

• Water, gas, short-chain fatty-acid

production

Absorption

Carbohydrates and Health

• Lactose Intolerance

• Diabetes• Dental caries• Constipation• Hyperactivity• Obesity• Heart Disease

Lactose Intolerance• Symptoms

– Abdominal discomfort– Bloating; Intestinal gas formation– Diarrhea

• Causes– Primary: Lactase deficiency– Secondary: Mucosal damage

p. 89-90

Lactose Intolerance• Prevalence (p. 111)• Ethnic <10% to >80%

– <10% Northern Europeans (Scandinavians)– 20% Caucasians– 50% Hispanics– 60% Inuits– 70% Mediterranean peoples– 75% African Americans– 80% Native Americans– >80% Southeast Asians

Lactose Content of Food• Whole wheat bread 1 slice 0.5gm• Cheese 1 oz 0.5-0.8

– Cheddar/American– Parmesan/Cream

• Doughnut, cake type 1.2• Chocolate 1 oz 2.3• Sherbet 1 c 4.0• Cottage cheese 7.5• Ice Cream 1 c 9.0• Milk 1 c 12.0• Yogurt 1 c 15.0

Lactose Intolerance• Dietary changes

– May not require the elimination of milk/milk products

– Acidophilus milk– Kefir, yogurt– Adequate calcium intake– Conservative vs liberal approach

Blood Glucose

• Regulating hormones– Insulin

•Controls transport of glucose

– Glucagon•Release glycogen from liver stores

– Epinephrine•Signals liver to release glucose

p. 82, 89

• How thebodyregulatesbloodglucose

p. 96

Blood Glucose• Hypoglycemia

– Rare in healthy people

• Diabetes– Type 1 diabetes

•Failure of insulin production– Type 2 diabetes

•Obesity

Blood Glucose• Glycemic response

– How quickly and how high blood sugar rises after eating

• Glycemic index– Method of classifying

foods according to their potential for raising blood glucose

p. 118

Blood Glucose• Glycemic Load

– Refers to both the Glycemic Index and the total amount of carbohydrate contained in the food

• Factors Influencing Glycemic Index– Effect of mixed meal– Fat, fiber, protein content of food– Amount and type of CHO eaten

CAUTION

Added Sugars• Sugars added to a

food for sweetening or other purposes– Do not include

natural sugars

• Other purposes:– Prevent spoilage– Browning– Food for yeast– Hold moisture p. 88

38

Examples of Added Sugars• White sugar (sucrose)• High-fructose corn syrup or corn

syrup• Invert sugar• Brown sugar• Molasses• Honey• Powdered sugar• Raw sugar• Demerara sugar

Sugars

• Nutrient density

• Overused in USA

Sugars

• Health effects of sugars– Dental caries

•Dental plaque

p. 88

Oral Health and ……• 20% increase in

CVD risk• Risk for stroke

even stronger • Release cytokines,

CRP, TNF• Endothelial damage• Plaque attachment

http://www.videomd.com/OralHealthandCardiovascularDisease-fv-4794.aspx

Controversies Of Sugar

• Sugar causes obesity

• Sugar causes heart disease

• What about HFCS?

p. 88-89

Controversies Of Sugar

• Sugar causes misbehavior in children and criminal behavior in adults

• Sugar causes cravings and addictions– Serotonin- mood elevator

p. 89

Recommended Intakes of Sugars

• DRI– No more than 25% of total daily

energy intake•Average U.S. Intake=105#/yr

»30 teaspoons/day

Starch and Fiber• Health effects

– Heart disease– Diabetes– GI health– Cancer– Weight

management

Viscous Fibers• SOLUBLE and more fermentable• Gums and mucilages• Pectins• Psyllium• Some hemicelluloses

Viscous Fibers• Sources

– Whole-grains, fruits, legumes, seeds and husks, vegetables

Viscous Fibers• Lower blood cholesterol• Slow glucose absorption• Slow transit of food through upper

GI tract• Holds moisture in stools, softening

them

Viscous Fibers• Yield small fat molecules that the

colon can use for energy

• Lower risk of heart disease

• Lower risk of diabetes

Viscous Fibers

Nonviscous Fibers• INSOLUBLE and less fermentable• Cellulose• Lignins• Psyllium• Resistant starch• Many hemicelluloses

Nonviscous Fibers

• Sources– Brown rice,

fruits, legumes, seeds, vegetables, wheat bran, whole grains

Nonviscous Fibers• Increase fecal weight

• Speed fecal passage through colon

• Provide bulk and feelings of fullness

Nonviscous Fibers• Alleviate constipation

• Lower risks of diverticulosis, hemorrhoids, appendicitis

• May help with weight management

Nonviscous Fibers

Starch and Fiber• RDA for carbohydrate

– 130 g/day– 45% - 65% total daily energy

intake• Daily Value: 300 g/day; 60% of

2000 kcal diet• Fiber

– Daily Value: 25 gm/day– AI: 14 gm/1000 kcal/day

Fiber• Grains

– Whole Wheat or

– 100% Wheat vs

– Wheat Bread

More on Fiber

• Vegetables– ½ c. dry beans, carrots=5-7 gms– ½ c. corn=2 gm; 1c. tomatoes=2 gm– ½ c. broccoli=3-6 gm

• Fruits– 1 pear=4-6 gm; canned=4 gm/1c– 1 apple=3-5– 1 banana, orange=3

Fiber and Food Processing

• How much fiber is there in each food?

1 apple 1 c. applesauce 1 c. apple juice

Food Item Amount Dietary Fiber

100% Bran cereal or Miller’s Bran

1/2 cup or 2 Tablespoons

10-14 grams

Whole Wheat Bread

2 slices 4 grams

Fresh Fruit 2 pieces 4 grams

Vegetables 2 servings 4 grams

Total 22-26 grams

Robertson’s Rule of 2’s

Alternatives to Sugar• Artificial sweeteners & sugar

replacers (nutritive sweeteners)• Stevia-natural, herbal alternative• Guidelines for Use:

– More sweet than sugar; use less– FDA approved (p.119 )– Caution when used in cooking

Hot Topic p. 119-121

Alternatives to Sugar• Caution: Patients with PKU

• Acceptable Daily Intake (ADI)p. 119

Objectives

• After reading Chapter 3 and class discussion, you will be able to:– Describe the functions of CHO– Identify the classification of CHO– Describe CHO digestion & absorption– Identify food sources of CHO– Calculate calories from CHO

Objectives

• Differentiate between soluble and insoluble fiber

• Identify foods that are a significant source of fiber

• Discuss health related effects of CHO in– Diabetes -Heart Disease– Obesity -GI -Cancer