The Carbohydrates

Sugars Starches 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

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 4

Categories of Carbohydrate • Simple

carbohydrates

– Natural sugars – Added (Refined) sugars • Complex

carbohydrates

(polysaccharides) – Starch – Fiber 5

Carbohydrates

• Simple carbohydrates –Monosacchares –Disaccharides • Complex carbohydrates –Glycogen –Starches –Fibers

Glucose

Fructose & Galactose

p. 103

Monosaccharides and Disaccharides

9

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 Carbohydrates Chemical Structure p. 109 Fig 3-7

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.

13

Complex Carbohydrates

• Fibers –Cellulose –Hemicelluloses –Pectins –Legnin –Gums and muscilages –Resistant starches p. 108-109

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 • Polysaccharide – Glycogen -Starches -Lactose -Fibers

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 20

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. 110

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 • Chocolate 1 oz • Sherbet 1 c • Cottage cheese • Ice Cream 1 c • Milk 1 c • Yogurt 1 c 1.2

2.3

4.0

7.5

9.0

12.0

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. 104

• How the body regulates blood glucose p. 114

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

CAUTION • 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 eating

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. 100-102

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 38

• Nutrient density • Overused in USA

Sugars

p. 101

Sugars

• Health effects of sugars –Dental caries •Dental plaque p. 102

p. 104

Controversies Of Sugar

• Sugar causes obesity • Sugar causes heart disease

Controversies Of Sugar

• Sugar causes misbehavior in children and criminal behavior in adults • Sugar causes cravings and addictions –Serotonin- mood elevator p. 105

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 –Extracted and used as food additives

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

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

Robertson’s Rule of 2’s

Food Item Amount Dietary Fiber 100% Bran cereal or Miller’s Bran 10-14 grams 2 Tablespoons Whole Wheat Bread Fresh Fruit 2 slices 2 pieces 4 grams 4 grams Vegetables 2 servings 4 grams Total 22-26 grams

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.134; H4-1;H4-3 ) –Caution when used in cooking

Alternatives to Sugar

• Caution: Patients with PKU • Acceptable Daily Intake (ADI) p. 135-138

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