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

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 Carbohydrates Chemical 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

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

Lactose Intolerance Prevalence (p. 111) Ethnic 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 –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 the body regulates blood glucose 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 isease-fv-4794.aspx

Controversies Of Sugar Sugar causes obesity Sugar causes heart disease What about HFCS? p

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 apple1 c. applesauce 1 c. apple juice

Food ItemAmountDietary Fiber 100% Bran cereal or Miller’s Bran 1/2 cup or 2 Tablespoons grams Whole Wheat Bread 2 slices 4 grams Fresh Fruit2 pieces 4 grams Vegetables2 servings 4 grams Total22-26 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

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