The Carbohydrates Sugars Starches Fiber Objectives After reading Chapter 3 and class discussion, you...
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Transcript of The Carbohydrates Sugars Starches Fiber Objectives After reading Chapter 3 and class discussion, you...
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
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
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
• 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
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
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
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
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
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
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
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
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