137Sport NutritionDr. A P L TongNutrition Physical performance138MacroMacronutrients(few grams daily)carbohydratelipidproteinwater• (as biological fuels) provide energy to maintain body functions (during rest & all forms of activities)• maintain the organism’s structural and functional integrityNutrition• is often defined as the total of processes of ingestion, digestion, absorption, and metabolism of food and the subsequent assimilation of nutrient materials into the tissues.• 6 categories: carbohydrates, lipids, proteins, vitamins, minerals and waterFoodMicroMicronutrients ( <1 g per day)vitaminsmineralstrace elements(1)Promotion of growth & development (protein)(2)Provision of energy (carbohydrate & fat)(3)Regulation of metabolism (vit, minerals & protein)Nutrients to take in for digestion139photosynthesisFoodrespirationEnergy• all nutrients except water and minerals contain carbon (organic)140CarbohydratesCarbohydrates•carbon + water, general formula: [CH2O]n•all living cells contain carbohydrates•main source: plants•Glucose– the most typical sugar (6-carbon), simple sugar, also called dextrose or blood sugar•Fructose (fruit sugar) and galactose, two other simple sugars but with slight different structures to glucose (they have uniquely different biochemical characteristics). Absorbed in the small intestine where it can be•directly used by cells for energy•stored as glycogen in muscles or liver for later use•converted to fat and stored for energyThe sweetest of the simple sugars141Kinds & Sources• 4 categories: monosaccharides, disaccharides, oligosaccharides, and polysaccharides• number of simple sugars linked together in a molecule determines each type•Glucose, fructose and galactose –monosaccharides•lactose (milk sugar), maltose (found in beer, cereals and germinating seeds), sucrose –disaccharides•araban, xylan –oligosaccharides(3-9)•cellulose, glycogen, starch (amylose and amylopectin) –polysaccharides(10 – thousands)CarbohydratesGlucose + galatoseGlucose x 2Glucose + fructose, sucrose is the most common dietary disaccharideSource: seed legumes[CH2O]n142Sucrose=glucose + fructose• the most common dietary disaccharide, ~25% of the total caloric intake in the US• occurs naturally in most food containing carbohydrates e.g. cane sugar, brown sugar, maple syrup and honey Carbohydrates
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