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Learn about classes of nutrients, types of carbohydrates, fats, and their roles in the body. Explore dietary recommendations and common myths about carbohydrates. Discover the importance of lipids, fats, and proteins in your diet.
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Nutrition I General Concepts
Classes of Nutrients • Carbohydrates • Proteins • Fats • Vitamins • Minerals • Water
Carbohydrates (3 types) • Monosaccharides: glucose, fructose, galactose (hexoses) • Disaccharides: • sucrose = glucose + fructose • [simple] (pop, candy, sweets) • Maltose = glucose + glucose • Lactose = glucose + galactose • Polysaccharides
Carbohydrates • Digestion convert all CHO to glucose • Glucose fates • Cell energy: glycolysis • Stored as glycogen in muscle and liver • Converted to fat for energy storage • Carbon skeleton for synthesis of non-essential amino acids
Carbohydrates • Two types of polysaccharides: • Animal • Plant • Two forms of plant polysaccharides: • Starch [complex carbohydrate] (pasta, rice, breads) • Fiber (cellulose, gums, hemicellulose, pectin) • What’s good about fiber?
Ways to Get More Fiber • Eat more fruits and vegetables • Eat whole grain foods
BRAN - B vitamins - minerals ENDOSPERM - dietary fiber - starch - protein - some iron and GERM B vitamins - essential fats - minerals - vitamins (B's , E and folacin) A Grain of Wheat
Polysaccharides • What is the major animal polysaccharide? • Approximately how many calories of animal polysaccharide can an 80-kg person store? • Where is it stored?
Polysaccharides What is glycogenolysis? What is gluconeogenesis? Liver Glycogen Muscle Glycogen Amino Acids Blood Glucose Muscle Glucose Glucose Energy
Carbohydrate Role • Energy Source • Protein Sparer • Metabolic Primer (fats burn in carbohydrate fire) • Fuel for central nervous system
Recommended Carbohydrate • What is the typical amount of carbohydrate consumed as % of total calories? • What is the recommended carbohydrate intake as % of total calories for physically active man and woman?
C 100 A 35% R 50% 80 SIMPLE 55% P B E O R H 60 65% C Y E D 50% 40 COMPLEX 45% N R T A 20 T E S 0 1910 1950 1980 Trends in Carbohydrate Consumption
Carbohydrate Confusion • Consumption of low-fiber processed starches stimulates overproduction of insulin which increases TGs & fat synthesis • Variables for metabolic syndrome • Abdominal fatness • Triacylglycerides • Low HDL • High BP • High fasting blood glucose
Carbohydrate Confusion • Glycemic index: measures the rise in blood glucose level after ingestion of equal quantities of carbohydrate containing food • Glycemic load: quantifies overall glycemic effect of a portion of food • Low glycemic index foods slower passage of food into small intestine; fiber slows digestion rate
Carbohydrate Utilization in Exercise • What is the primary fuel during intense exercise of short duration? • What is the utilization of CHO during initial stage of moderate but prolonged?
Carbohydrate Utilization in Exercise • What is the utilization of CHO during middle stage of moderate but prolonged? • What is the utilization of CHO during last stage of moderate but prolonged?
Lipids • Common simple fat in body: triacylglyceride. • Molecular structure: glycerol & 3 carbon chains (fatty acids)
Sources of Fats • Animal (saturated) • Vegetable (unsaturated) • Poly-unsaturated • Mono-unsaturated
Composition of Oils (%) Type Sat Poly Mono safflower 9 75 16 sunflower 10 66 24 corn 13 59 28 soybean 14 58 28 sesame 14 42 44 peanut 17 32 51 palm 49 9 42 olive 14 8 78 canola 7 35 58
Dietary Fat Recommendations • Less than 30% of calories in diet from fat • Less than 1/3 of dietary fat should be saturated • Less than 10% of total calories from saturated fat
PRO PRO (10-15%) CHO FAT (<30%) FAT CHO (55-60%) Recommended Dietary Intake
PRO PRO (13%) CHO FAT (40%) CHO (47%) FAT Actual Dietary Intake (Average American)
Caloric Content of Foods Carbohydrates 4 cal/g Protein 4 cal/g Fats 9 cal/g Alcohol 7 cal/g
Caloric Density Boloney & Turkey 80% "fat free” 98% “fat free” 30 calories/slice 1 gram fat /slice 52 calories / slice 4 grams fat / slice Calories from fat = 4 g/slice x 9 cal/g = 36 cals Calories from fat = 1 g/slice x 9 cal/g = 9 cals Percent of calories from fat = 36 cals /52 cal total = 69% Percent of calories from fat = 9 cals /30 cal total = 30%
Compound Lipid: Lipoproteins • High Density Lipoproteins • Low Density Lipoproteins • Very Low Density Lipoproteins What are the dietary implications of these lipoproteins?
Lipids Trans Fatty Acids What makes trans FA dangerous? Fish Oils Contain 2 PUFAs Eicosapentaenoic & Docosahexanoic Improve lipid profile
Lipids Role in Body • Energy reserve • 150 lb x .25 x 3500 = 131,250 kcals • Protection of vital organs & thermal insulation • Carrier fat soluble vitamins What aspect of lipid causes it to contain more energy than equal weight of CHO?
Protein: (Amino Acids - 20) • Non-essential (11) • Essential (9) • Valine • Leucine • Isoleucine • Threonine • Lycine • Histidine • Phenylalanine • Tryptophan • Methionine How does chemical structure of protein differ from carbohydrate and lipid?
Sources of Protein • Animal (complete) • meats, dairy • Vegetable (incomplete) • beans, nuts, legumes, grains • What is synthesis of a nonessential amino acid from C, O, and H called?
Protein Requirements • RDA average = .8 g/kg/day • RDA athlete = 1.2-1.6 g/kg/day High levels of protein intake above 2 g/kg/day can be harmful to the body Why is excessive protein harmful? What does body do with excessive protein?