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Introduction to Human Nutrition

Introduction to Human Nutrition. Course Web Page. Real Hope for Haiti – Clinic for Malnourished Children. Chapter Outline. Nutrition defined Classifying the nutrients Nutritional research Nutrition and health Healthy People 2020 goals Hunger and appetite (next class)

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Introduction to Human Nutrition

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  1. Introduction to Human Nutrition Course Web Page

  2. Real Hope for Haiti – Clinic for Malnourished Children

  3. Chapter Outline • Nutrition defined • Classifying the nutrients • Nutritional research • Nutrition and health • Healthy People 2020 goals • Hunger and appetite (next class) • Factors impacting food choices • Small group exercise

  4. Nutritional Goals • Quality intake that allows you to function at your best and promotes health. • Intake that provides adequate levels of each nutrient • Quantity of intake that promotes a healthy body weight.

  5. Nutrition Defined • Nutrition – the science of foods and the nutrients they contain • Study the: • action of foods and the nutrients in the body • relationship between diet and health

  6. Nutrition Defined • Actions in the body include: • Ingestion • Digestion • Absorption • Transport • Metabolism • Excretion

  7. What’s Considered Food? • Foods contain nutrients and are derived from plant or animal sources • Nutrients are used by the body to provide energy and to support growth, maintenance and repair of body tissues • ~ 40 nutrients identified at this time

  8. Classifying Nutrients There are 6 Classes of Nutrients 1. Carbohydrates 2. Lipids (fats) 3. Proteins 4. Vitamins 5. Minerals 6. Water

  9. Body Composition

  10. Describing the Nutrients • There are several ways to classify the classes of nutrients. • Essential or nonessential • Organic or inorganic • Macronutrient or micronutrient • Energy yielding or not

  11. Classifying Nutrients • Essential nutrients– nutrients the body either cannot make or cannot make enough of to meet its needs. • These nutrients must be obtained from foods (ingested in some manner) • Examples: • Vitamins • Calcium, iron, and other minerals • Some of the amino acids

  12. Essential Nutrients • To be classified as an essential nutrient: • The biological function of nutrient is known • Omission from the diet leads to a decline in a biological function • Return of the nutrient restores the biological function

  13. Classifying Nutrients • Nonessential nutrients– body can make from other nutrients ingested  Examples: • Cholesterol • Some amino acids

  14. Classifying Nutrients by Composition • Organic nutrients - contain carbon • Carbohydrates • Lipids • Proteins • Vitamins • Inorganic nutrients - do not contain carbon • Minerals • Water

  15. Quantity Needed • Macronutrients: need in relatively large amounts • Carbohydrates, lipids, proteins • Micronutrients: need in relatively small amounts • All other nutrients

  16. Classifying Nutrients • Energy-yielding nutrients (3): • Carbohydrates • Fats (lipids) • Proteins • Where does the energy come from?

  17. A little more on energy • Measure energy in kilocalories in U.S. • What most think of as a “calorie” is really a kilocalorie • Kcal = amount of energy needed to raise the temperature of 1 kg of water by 10C • Measure energy in kilojoules (kJ) in most other countries

  18. Energy in the Body • The body uses the energy yielding nutrients to fuel all activities • All energy yielding nutrients are “caloric”. • If more energy is ingested than is needed to fuel body activities the extra energy is stored as _________ and ________ occurs.

  19. Energy-Yielding Nutrients

  20. Energy-Yielding Nutrients • Carbohydrates: C, H, O • 4 kcal/gram • Body’s primary source of energy • Use as glucose • Glucose is the brain’s only source of energy • Carbohydrate stores are limited ~12-24 hours (in liver and muscle)

  21. Classes of Carbohydrates • Simple sugars • Monosaccharides and disaccharides • Complex carbohydrates • Starch • Fibers • Carbohydrate rich foods……..

  22. Lipids • Lipids – fats and oils: C, H, O • 9 kcal/gram • Body’s alternate source of energy • Use fat along with glucose as an energy source most of the time • Stores are unlimited

  23. Types of Lipids • Fats – solids • Oils – liquids • Saturated (solids/fats) • No carbon to carbon double bonds • Unsaturated (liquids/oils) • Carbon to carbon double bond(s) present • Lipid rich foods?

  24. Proteins • Proteins: C, H, O, N, S • 4 kcal/gram (same as _______) • Body’s least desirable source of energy • WHY? ……. • Protein is used for energy only when carbohydrate is NOT available as an energy source. • Protein rich foods?

  25. Energy-Yielding Non-nutrient • Alcohol – 7 kcal/gram • Non-nutrient because it interferes with growth, maintenance and repair of the body • Alcohol’s metabolites are harmful

  26. Energy Density • Measure of the kcal per gram of food • _______ has the highest energy density of the 3 energy-yielding nutrients. • Foods with a high energy density provide more kcal per gram than low density foods.

  27. Energy Density

  28. Evaluating a Food Label • _____ grams carbohydrate • _____ grams fat • _____ grams protein • TOTAL KCAL: ____________

  29. 6 Classes of Nutrients • Carbohydrates • Lipids (fats and oils) • Proteins • Vitamins • Minerals • Water Pages 8/9

  30. Vitamins • Essential • Organic, micronutrient • Not energy-yielding • Can be water-soluble or fat-soluble Examples:

  31. Minerals • Essential • Inorganic, micronutrient • Major minerals: Ca, P, Na • Trace minerals: Fe, Zn • Not energy-yielding • Indestructible

  32. Water • Water (H2O) • Essential • Organic or inorganic? • Noncaloric • We are ~60% water

  33. Not everyone has access to clean water

  34. The Science of Nutrition • One of the newest sciences • New branch is nutritional genomics • Study of the interaction of nutrients with DNA/genes and how those genes impact health • Like all sciences, nutrition is based on scientific research

  35. Scientific Method • Observations  Questions • Hypotheses  Predictions • Test hypotheses/predictions • Analyze data and draw conclusions • Share results

  36. Observations and Questions • Make observations about diet and health. These observations lead to questions For example: • The incidence of breast cancer is much lower in Japan than in the U.S. • Diet in Japan is rich in…..while in U.S. diet is rich in …… • Question?:

  37. Develop Hypotheses and Make Predictions • Hypothesis – tentative explanation of the observations or answer to the question • Make prediction – If the hypothesis is true what else is true?

  38. Experiments • Conduct experiments to test the predictions • Easier said than done when people are involved! • We’ll consider research designs later/soon.

  39. One Experimental Design • When possible, randomly assign subjects to either a control of experimental group • Goal is for two groups to be as similar to each other as possible • Control Group – either no change to diet or given a placebo • Experimental group – diet changed or given a supplement

  40. Experimental Design • Compare the health/lab values of the two groups before and after the diet change. • Example – DASH diet study

  41. Analyze results… • Analyze results • Draw conclusions about the validity of the hypothesis • Test alternate hypotheses • Share findings • Publish in nutritional journals • Present findings at conferences

  42. Common Research Designs • Epidemiological study (observe) • Cross-sectional • Longitudinal • Case-control study • Experimental (intervene) • Animal studies • Human clinical trials • Double blind study • Lab studies page 25

  43. The Science of Nutrition 1. Epidemiological studies • Study of populations • Look for correlations between dietary practices and health

  44. Epidemiological Studies Cross-sectional - look for correlations between diet and health at a point in time Longitudinal Studies - Follow a group of people (a cohort) over a period of time • Look for differences in diet that might account for the differences in health

  45. Epidemiological Studies • Case-control study – compare the diet of individuals with a condition to that of healthy individuals • Again, do not change their diet…..just observe it.

  46. Human Experimental Studies Often called a Clinical Study • Randomly assign like people to either the experimental or control group • Alter the diet of experimental group as compared to a control group • Compare incidence of disease/lab values/ performance …. of two groups

  47. Types of Clinical Trials • Blind experiments • Subjects do not know which group they are in • Double blind experiments • Neither subjects nor the researchers know which group the subjects are in until after the experiment is over • Goal is to avoid bias in the reporting/recording of the data.

  48. Experimental Studies Animal Studies • Controlled studies in lab setting using animals • Alter diet of experimental group • Compare health/lab values of control and experimental groups • Benefits? …. • Drawbacks? ……

  49. Experimental Studies Lab-Based Studies • Also called in vitro studies • Examine impact of a substance on living tissue in a “test tube” -------------------------------------------------------------

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