Exam 1 Study Guide Nutritional Science study of the nutrients in foods and the body also the human behaviors related to food Nutrient components of food that are required for the body s basic functioning Research Designs Case studies individual Epidemiological studies populations Cohort studies group Intervention studies need control and experimental groups Laboratory Studies usually with animals Nutrition Labeling and Education Act of 1990 NLEA Established which foods should be labeled Processed packaged foods regulated by FDA must carry nutrition labeling USDA labeling for packaged meat and poultry products Serving sizes are standardized but by weight Emphasis on calories fat cholesterol sodium Daily Value daily intake of a nutrient recommended per day based on a 2 000 calorie diet Below 10 low poor source of nutrient Above 20 high excellent source of nutrient Less than 5 grams of fat fat free Up to 3 grams of fat low fat 25 less than a reference food less fewer reduced Less than 5 calories calorie free Less than 40 calories low calorie Classes of Nutrients Protein Carbohydrates Lipids provide energy Vitamins Minerals Water don t provide energy but still necessary Milk contains all of the 6 classes of nutrients What is a calorie Food energy Measured in kilocalories Amount of heat energy needed to raise the temp of one kilogram of water by one degree Celsius measured by bomb calculator 4 kcal gram protein 4 kcal gram carbohydrates 9 kcal gram lipids 7 kcal gram alcohols Vitamins minerals and water do not provide energy Characteristics of a Nutritious Diet Adequacy correct amount of nutrients Balance each food group Moderation small amounts of food that s bad for you Variety receive other nutrients reach toxicity level if too much Calorie control amount of calories you take in in relation to the calories you burn Nutrient Density Nutrient Content Kilo Calorie Content Tools for Diet Evaluation Dietary Reference Intakes DRI umbrella term for RDA EAR AI and UL recommended intakes of specific nutrients to prevent deficiency and chronic disease Dietary Guidelines for Americans 1980 2010 Myplate based on dietary guidelines to help consumers make better food choices Recommended Dietary Allowances RDA levels of nutrient intake adequate to meet needs of nearly all healthy people in the US set for energy protein vitamins and minerals different for age gender lactaiding mothers etc Setting RDA for a Nutrient 1 Estimate average need 2 Add 30 50 to cover needs of almost all in that group 3 Add more to account for absorption Setting RDA for Energy 1 Set average amount needed by a group 2 Set high to allow some variation over tome and cover most of the population If you consume less than 2 3 you re at higher risk for deficiency Excess may be harmful This is a recommendation not a requirement Adequate Intake AI same as RDA but lacking enough scientific evidence to set an RDA ex Calcium Estimated Average Requirement EAR amount that meets optimal nutrient needs of half the individual in a specific group Tolerable Upper Intake Level UL total intake from food fortified food and supplements should not exceed this amount or adverse health effects may result not a recommended amount The Mouth The Esophagus The Stomach Chewing Saliva contains amylase and lipase Starch broken down into polysaccharides Triglycerides break down to fatty acids monoglycerides and diglycerides primarily in infants Smooth tube of muscle food moves through by peristalsis Lower esophageal sphincter controls the rate at which food enters the stomach and keeps stomach contents from coming back up Gastric juice HCL enzymes water mixes with food to produce chime HCL denatures proteins Pepsin breaks down proteins into smaller polypeptides Salivary amylase is deactivates salivary lipase becomes active Mucus lining protects stomach wall Pyloric sphincter controls rate at which chime enters small intestine Loss of part of stomach may lead to malabsorption Pancreas Produces bicarbonate neutralize acid Produces amylase and lipase Produces protease breaks up polypeptides Liver Produces bile Gall bladder Stores bile Small Intestine Carbohydrates Liver and Gall bladder work together and release products into small intestine to aid in digestion Pancreatic amylase continues to breakdown starch to disaccharides Enzymes on the surface of the small intestinal cells hydrolyze the disaccharides into monosaccharides and cells absorb them Pancreatic and small intestinal proteases split polypeptides further Dipeptides tripeptides and amino acids di and tri peptides produced by cells of small intestine break down Into amino acids Proteins Lipids Bile flows from gall bladder through common bile duct Bile emulsifies breaks down fats Pancreatic lipase flows from pancreatic duct Mon glycerides glycerol and fatty acids are absorbed Brush Border Membrane Small intestine has many folds finger like projections give more surface area Villi secretion of digestive enzymes Covered with smaller projections called micro villi Sight for absorption of nutrients Villi have capillaries and lymph vessels in the center Capillaries carry away water soluble nutrients Lymph vessels carry away lipid soluble materials Large Intestine Reabsorbs water and minerals Home for micro flora Undigested fiber passes into the colon and is broken down by bacterial enzymes Fiber holds water regulates bowel activity and binds to cholesterol as well as other minerals carrying them out of the body Carbohydrates Functions Main source of energy for cells Spare protein Add bulk to foods Provide energy Sources Grains Fruits Dairy products Simply carbs sugars C6HO Complex carbs starches and fiber Polysaccharides long chains of sugar units Monosaccharides 6 carbon molecules Glucose body s predominant fuel Fructose fruit sugar Galactose one of the two components of the sugar in milk lactose Disaccharides Sucrose glucose and fructose Maltose glucose and glucose Lactose glucose and galactose Polysaccharides Glycogen animal starch long chains of glucose body s storage for of carbs Starch from plant sources Fiber plant material long chains of glucose whose structure is resistant to enzymatic degradation cellulose pectin and hemicellulose Benefits of fiber 20 30g per day Less risk of heart disease hypertension diabetes and bowel disease Promotion of healthy body weight High fiber lower cholesterol and lower heart risk Prevention of diverticula infected pockets formed in the colon Regulation of blood
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