Chapter 1 The Science of Nutrition 01 25 2010 Nutrition behaviors related to food Why is it classified as a science The study of the nutrients in foods and the body also the human It uses the scientific method to uncover unknown nutrition facts New findings must be repeated before they can be considered valid New findings must withstand the test of time Scientific Method Observations Formulate hypothesis o Best guess to explain observation Test hypothesis o Different study designs Evaluate study results Compare to original hypothesis Revise hypothesis 01 25 2010 Why eat Have to o physiological response o hunger Want to o psycho social response o appetite What causes hunger Hypothalamus o Satiety center in brain o Processes nerve signals from throughout the body Hormones brain chemicals o Cortisol from adrenal glands stress hormone o Leptin from adipose fat tissue o Neuropeptide Y from hypothalamus Composition of Meals o Dietary fiber and water more filling o Stomach expansion Appetite Media 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 genetics Comfort foods Ethnic heritage Weight control Advertising Prevent disease Influences on Food Availability Natural environment o Climate o Topography of land o rainfall Technology o Farming practices o Food storage o Food distribution o Advertising Economics Population o income o demand o Size o Structure o cash crops vs food for family consumption Classes of nutrients Proteins Carbohydrates Lipids fats Vitamins Minerals Water Milk Protein casein Carbohydrates lactose Lipid even skim milk Vitamins A and D Minerals calcium Water 87 What is a calorie water by 1 degree C o measured by bomb calorimeter Kilocalorie kcal a unit of energy heat Proteins 4 kcal gram Carbohydrates 4 kcal gram Lipids 9 kcal gram the amount of energy needed to raise the temperature of one kilogram of Alcohol 7 kcal gram Vitamins minerals water do not provide energy Requirements for nutrients Proteins Carbohydrates Lipids grams Vitamins Minerals milligrams micrograms What else is in my food Some foods contain beneficial non nutrients called phytochemicals Characteristics of a nutritious diet Adequacy Balance Moderation Variety Calorie balance NUTRIENT DENSITY Nutrient content kilocalorie content 2 1 Dietary Guidelines 01 25 2010 General goals for nutrient intake and diet composition set by USDA and DHHS Revised every 5 years Newest revision released January 13 2005 Avoidance of chronic disease Dietary Guidelines 2005 Finding Your Way to A Healthier You Make smart choices from every food group o Emphasize fruits vegetables whole grains and fat free or low fat milk products o Include lean meats poultry fish beans eggs and nuts o Low in saturated fats trans fats cholesterol salt and added sugars Find your balance between food and physical activity o Be physically active for at least 30 minutes most days of the week Get the most nutrition out of your calories o Nutrient density o Choose the most nutritionally rich foods from each group Avoid obesity Macronutrient breakdown of diet Total fat 20 35 of kcal o Less than 10 saturated fat o Less than 300 mg cholesterol CHO 45 65 of kcal Protein 10 35 of kcal Mix up your choices within each food group Focus on fruit Vary your veggies Get your calcium rich foods Make half your grains whole Go lean with protein Check servings and calories Make your calories count Don t sugarcoat it Know your fats Reduce sodium increase potassium Play it safe with food Use the Nutrition Facts Panel to make nutritious food choices Clean hands food contact surfaces fruits and vegetables Separate raw cooked and ready to eat foods while shopping preparing and cooking Chill perishable foods promptly and thaw foods properly About alcohol Sodium If you choose to drink alcohol do so in moderation Less than 2300 mg approx 1 tsp of sodium per day figure out serving sizes of each food group to eat Focus of Food Guide pyramid The USDA Food Guidance system Icon is the Food Guide Pyramid First created in 1992 Most recent revision 1995 www mypyramid gov Activity Moderation Personalization Proportionality Variety Gradual improvement Discretionary calories How much should I eat Bread cereal rice and pasta o 3 8 ounce equivalents o 1 slice of bread o 1 ounce of ready to eat cereal o cup of cooked cereal rice or pasta Vegetables o 1 3 cups o 2 cup of raw leafy vegetables Fruit o 1 2 cups o 1 medium apple banana or orange o cup of chopped cooked or canned fruit o cup of fruit juice Milk yogurt and cheese o 2 3 cups o 1 cup of milk or yogurt o 1 ounces of natural cheese Meat poultry fish dry beans eggs and nuts o 2 6 ounces o 1 ounce of cooked lean meat poultry or fish o 1 4 cup of cooked dry beans o 1 egg o ounce nuts or 1 tablespoons of peanut butter Serving vs portion o Serving a unit of measure o Portion amount of food actually served or consumed Dietary Reference Intakes Umbrella term for RDA EAR AI and UL Recommended intakes of specific nutrients to prevent deficiency and chronic disease Recommended 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 RDA For a nutrient o Estimate the average need for a group o Add 30 50 to cover needs of nearly all in that group o May add more to account for absorption For energy Keep in Mind o Set at the average amount needed by a group 1 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 RDA Estimated 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 plan diets for groups of players Tolerable Upper Intake Level UL Total intake from food fortified food and supplements should not
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