NutritionThe study of the nutrients in foods and the body, also the human behaviors related to food.Why is it classified as a science?It uses the scientific method to uncover unknown nutrition factsNew findings must be repeated before they can be considered validNew findings must withstand the test of timeScientific MethodObservationsFormulate hypothesisBest guess to explain observationTest hypothesisDifferent study designsEvaluate study resultsCompare to original hypothesisRevise hypothesisWhy eat?“Have to”physiological responsehunger“Want to”psycho-social responseappetiteWhat causes hunger?HypothalamusSatiety center in brainProcesses nerve signals from throughout the bodyHormones/ brain chemicalsCortisol from adrenal glands (stress hormone)Leptin from adipose (fat) tissueNeuropeptide Y from hypothalamusComposition of MealsDietary fiber and water more fillingStomach expansionAppetiteMedia, childhood experiences, peer influences, ethnic identity, education, occupation, income, rural-urban residence, dietary fat, fiber, and water content of foods, convenience, availability, food flavor, texture, and appearance, religious beliefs, nutritional knowledge, current health status, health benefits, geneticsComfort foodsEthnic heritageWeight controlAdvertisingPrevent diseaseInfluences on Food AvailabilityNatural environmentClimateTopography of landrainfallTechnologyFarming practicesFood storageFood distributionAdvertisingEconomics“cash crops” vs. food for family consumptionincomedemandPopulationSizeStructureClasses of nutrientsProteinsCarbohydratesLipids (fats)VitaminsMineralsWaterMilkProtein – caseinCarbohydrates – lactoseLipid – even skim milkVitamins - A and DMinerals – calciumWater – 87%What is a calorie?the amount of energy needed to raise the temperature of one kilogram of water by 1 degree Cmeasured by bomb calorimeterKilocalorie (kcal) – a unit of energy (heat)Proteins – 4 kcal/gramCarbohydrates – 4 kcal/gramLipids 9 kcal/gramAlcohol – 7 kcal/gramVitamins, minerals, water do not provide energyRequirements for nutrientsProteins, Carbohydrates, Lipids – gramsVitamins, Minerals – milligrams, microgramsWhat else is in my food?Some foods contain beneficial, non-nutrients called phytochemicalsCharacteristics of a “nutritious” dietAdequacyBalanceModerationVarietyCalorie balanceNUTRIENT DENSITYNutrient content/kilocalorie contentDietary GuidelinesGeneral goals for nutrient intake and diet composition set by USDA and DHHSRevised every 5 yearsNewest revision released January 13, 2005Avoidance of chronic diseaseDietary Guidelines, 2005: Finding Your Way to A Healthier YouMake smart choices from every food groupEmphasize fruits, vegetables, whole grains and fat free or low fat milk productsInclude lean meats, poultry, fish, beans, eggs and nutsLow in saturated fats, trans fats, cholesterol, salt and added sugarsFind your balance between food and physical activityBe physically active for at least 30 minutes most days of the weekGet the most nutrition out of your caloriesNutrient densityChoose the most nutritionally rich foods from each groupAvoid obesityMacronutrient breakdown of dietTotal fat 20-35% of kcalLess than 10% saturated fatLess than 300 mg cholesterolCHO 45-65% of kcalProtein 10-35% of kcalMix up your choices within each food groupFocus on fruitVary your veggiesGet your calcium rich foodsMake half your grains wholeGo lean with proteinUse the Nutrition Facts Panel to make nutritious food choicesCheck servings and caloriesMake your calories countDon’t sugarcoat itKnow your fatsReduce sodium, increase potassiumPlay it safe with foodClean hands, food contact surfaces, fruits and vegetablesSeparate raw, cooked and ready to eat foods while shopping preparing and cookingChill perishable foods promptly and thaw foods properlyAbout alcoholIf you choose to drink alcohol do so in moderationSodiumLess than 2300 mg (approx. 1 tsp) of sodium per dayThe USDA Food Guidance systemIcon is the Food Guide PyramidFirst created in 1992Most recent revision 1995www.mypyramid.govfigure out serving sizes of each food group to eatFocus of Food Guide pyramidActivityModerationPersonalizationProportionalityVarietyGradual improvementDiscretionary caloriesHow much should I eat?Bread, cereal, rice, and pasta3-8 ounce equivalents1 slice of bread1 ounce of ready-to-eat cereal½ cup of cooked cereal, rice, or pastaVegetables1-3 cups2 cup of raw leafy vegetablesFruit1-2 cups1 medium apple, banana, or orange½ cup of chopped, cooked, or canned fruit¾ cup of fruit juiceMilk, yogurt, and cheese2-3 cups1 cup of milk or yogurt1-½ ounces of natural cheese• Meat, poultry, fish, dry beans, eggs, and nuts–2-6 ½ ounces–1 ounce of cooked lean meat, poultry, or fish–1/4 cup of cooked dry beans–1 egg,–½ ounce nuts or 1 tablespoons of peanut butterServing vs. portionServing: a unit of measurePortion: amount of food actually served or consumedDietary Reference IntakesUmbrella term for RDA, EAR, AI and ULRecommended intakes of specific nutrients to prevent deficiency and chronic diseaseRecommended Dietary Allowances (RDAs)Levels of nutrient intake adequate to meet needs of nearly all healthy people in the U.S.Set for energy, protein, and many vitamins and minerals.Different RDAs for different age and gender groups.Also pregnant and lactating women.To set the RDAFor a nutrient:Estimate the average need for a group.Add 30-50% to cover needs of nearly all in that group.May add more to account for absorption.For energy:Set at the average amount needed by a group.Keep in Mind1. RDAs are recommendations, not requirements.2. They are suggested average daily intakes.3. They are set high to allow for some variation over time. Also, to cover most of the population.4. People who consistently consume less than 2/3 of the RDA for a nutrient may be at higher risk for a deficiency of that nutrient.5. Consuming nutrients greatly in excess of the RDA may be harmful.Adequate Intake (AI)Same as RDA, but lacking enough scientific evidence to set an RDAEstimated Average Requirement (EAR)The amount that meets the optimal nutrient needs of half the individuals in a specific group. (For health professionals to develop RDA's and plandiets for groups of players.)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.2/3Every packaged food must state:The common name of the
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