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 functioningResearch Designs:Case studies- individualEpidemiological studies-populationsCohort studies- groupIntervention studies-need control and experimental groupsLaboratory Studies-usually with animalsNutrition Labeling and Education Act of 1990 (NLEA)Established which foods should be labeled Processed, packaged foods regulated by FDA must carry nutrition labelingUSDA labeling for packaged meat and poultry productsServing sizes are standardized (but by weight)Emphasis on calories, fat, cholesterol, sodiumDaily Value- daily intake of a nutrient recommended per day based on a 2,000-calorie dietBelow 10% = low/poor source of nutrientAbove 20%= high/excellent source of nutrientLess than .5 grams of fat= fat freeUp to 3 grams of fat= low fat25% less than a reference food= less/fewer/reducedLess than 5 calories=calorie freeLess than 40 calories=low calorieClasses of Nutrients:Protein Carbohydrates Lipids provide energyVitamins Minerals Water don’t provide energy but still necessary**Milk contains all of the 6 classes of nutrients**What is a calorie?Food energyMeasured in kilocaloriesAmount of heat energy needed to raise the temp of one kilogram of water by one degree Celsius (measured by bomb calculator) 4 kcal/gram – protein4 kcal/gram- carbohydrates9 kcal/gram- lipids7 kcal/gram- alcohols**Vitamins, minerals and water do not provide energy**Characteristics of a Nutritious DietAdequacy- correct amount of nutrientsBalance-each food groupModeration- small amounts of food that’s bad for youVariety- receive other nutrients, reach toxicity level if too muchCalorie control- amount of calories you take in in relation to the calories you burnNutrient Density = Nutrient Content Kilo Calorie ContentTools 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 diseaseDietary Guidelines for Americans (1980-2010)Myplate-based on dietary guidelines to help consumers make better food choicesRecommended 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 Nutrient1. Estimate average need2. Add 30-50% to cover needs of almost all in that group3. Add more to account for absorptionSetting RDA for Energy1. Set average amount needed by a group2. 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 toset an RDA (ex. Calcium)Estimated Average Requirement (EAR)- amount that meets optimal nutrient needs of half the individual in a specific groupTolerable 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 amountThe MouthChewingSaliva contains amylase and lipaseStarch broken down into polysaccharidesTriglycerides break down to fatty acids, monoglycerides and diglycerides (primarily in infants)The EsophagusSmooth tube of muscle food moves through by peristalsisLower esophageal sphincter controls the rate at which food enters the stomach and keeps stomach contents from coming back upThe StomachGastric juice (HCL + enzymes + water) mixes with food to produce chimeHCL denatures proteinsPepsin breaks down proteins into smaller polypeptidesSalivary amylase is deactivates, salivary lipase becomes activeMucus lining protects stomach wallPyloric sphincter controls rate at which chime enters small intestineLoss of part of stomach may lead to malabsorptionPancreasProduces bicarbonate (neutralize acid)Produces amylase and lipaseProduces protease (breaks up polypeptides)LiverProduces bileGall bladder Stores bile*Liver and Gall bladder work together and release products into small intestine to aid in digestion*Small Intestine CarbohydratesPancreatic amylase continues to breakdown starch to disaccharidesEnzymes on the surface of the small intestinal cells hydrolyze the disaccharides into monosaccharides and cells absorb them.ProteinsPancreatic and small intestinal proteases split polypeptides further Dipeptides, tripeptides and amino acidsdi and tri peptides produced by cells of small intestine break downInto amino acidsLipidsBile flows from gall bladder through common bile ductBile emulsifies (breaks down) fatsPancreatic lipase flows from pancreatic duct Mon glycerides, glycerol and fatty acids are absorbedBrush Border MembraneSmall intestine has many folds, finger like projections give more surface areaVilli-secretion of digestive enzymes Covered with smaller projections called micro villiSight for absorption of nutrientsVilli have capillaries and lymph vessels in the centerCapillaries carry away water-soluble nutrientsLymph vessels carry away lipid soluble materialsLarge IntestineReabsorbs water and mineralsHome for micro floraUndigested fiber passes into the colon and is broken down by bacterial enzymesFiber holds water, regulates bowel activity and binds to cholesterol as well asother minerals, carrying them out of the bodyCarbohydratesFunctions: Main source of energy for cellsSpare proteinAdd bulk to foodsProvide energySources:GrainsFruitsDairy productsSimply carbs-sugars (C6HO)Complex carbs-starches and fiberPolysaccharideslong chains of sugar unitsMonosaccharides-6 carbon moleculesGlucose-body’s predominant fuelFructose-fruit sugarGalactose-one of the two components of the sugar in milk (lactose)DisaccharidesSucrose=glucose and fructoseMaltose= glucose and glucoseLactose=glucose and galactosePolysaccharidesGlycogen-animal starch, long chains of glucose (body’s storage for of carbs)Starch from plant sourcesFiber-plant material, long chains of glucose whose structure is resistant to enzymatic degradationcellulose, pectin and hemicelluloseBenefits of fiber (20-30g per day)Less risk of heart disease, hypertension, diabetes and bowel diseasePromotion of healthy body weightHigh fiber, lower cholesterol and lower heart riskPrevention of
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