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Introduction to Human Nutrition

Introduction to Human Nutrition. Chapter Outline. Nutrition defined Classifying nutrients Energy Nutrition and health Evaluating nutritional status Levels of nutritional status Deficiencies Nutritional research Nutritional recommendations Factors impacting food choices.

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Introduction to Human Nutrition

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  1. Introduction to Human Nutrition

  2. Chapter Outline • Nutrition defined • Classifying nutrients • Energy • Nutrition and health • Evaluating nutritional status • Levels of nutritional status • Deficiencies • Nutritional research • Nutritional recommendations • Factors impacting food choices

  3. Nutrition Defined • Nutrition – the science of foods and the nutrients and other substances they contain and their actions in the body.

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

  5. 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

  6. Nutrients • Multiple ways to classify the nutrients. • Nutrients can be classified as: • Carbohydrate, protein…… (6 classes) • Essential or nonessential • Organic/inorganic • Energy yielding

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

  8. Body Composition

  9. 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

  10. 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

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

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

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

  14. A little more on energy. • Measure energy in kilocalories in U.S. • Kcal = food calorie = Cal • What most think of as a “calorie” is really a kilocalorie • Measure energy in kilojoules (kJ) in most other countries

  15. Energy in the Body • The body uses the energy yielding nutrients to fuel all activities • Remember, all energy yielding nutrients are caloric.

  16. Energy-Yielding Nutrients • Carbohydrates: C, H, O • 4 kcal/gram • Body’s primary source of energy • Use as glucose • Brain’s only source of energy • Stores are limited ~12-24 hours (in liver and muscle) • Carbohydrate rich foods……..

  17. Energy-Yielding Nutrients • Fats: C, H, O • 9 kcal/gram • Body’s alternate source of energy • Use fat along with glucose as an energy source when ….. • Stores are unlimited

  18. Energy-Yielding Nutrients • Proteins: C, H, O, N, S • 4 kcal/gram (same as _______) • Body’s least desirable source of energy • WHY? ……. • Protein is used for energy when fat when carbohydrate stores are empty.

  19. Energy-Yielding Non-nutrient • Alcohol – C, H, O • 7 kcal/gram • Not considered a nutrient as it interferes with life functions • Alcohol metabolites are harmful!

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

  21. Energy in the Body • Weight is stable when energy in = energy out • Extra energy taken in is stored for later use • This results in weight gain • Store the extra energy as: • _____________________ • _____________________ • Inadequate energy intake results in weight loss

  22. 6 Classes of Nutrients • Carbohydrates • Lipids (fats) • Proteins • Vitamins • Minerals • Water

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

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

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

  26. Not everyone has access to clean water

  27. Nutrition Defined • NO NUTRIENT WORKS ALONE • Need regular adequate intake of all nutrients for optimal functioning. • Best obtained from food – not supplements. • WHY????

  28. Nutrition and Health • Nutrition and health are closely related • Chronic health issues associated with diet: • Obesity • Type II Diabetes • Osteoporosis • See page 25

  29. Leading Causes Death - US • Heart disease: 616,067 • Cancer: 562,875 • Stroke: 135,952 • Chronic respiratory diseases: 127,924 • Accidents (unintentional injuries): 123,706 • Alzheimer's disease: 74,632 • Diabetes: 71,382 • Influenza and Pneumonia: 52,717 • Kidney disease: 46,448 • Septicemia: 34,828 CDC, 2009

  30. Improving your Health • Goal is to reduce the number of risk factors that are in your control • Risk factor = something that statistically increases the incidence of a disease • Risk factors may not be the cause of the disease………

  31. Improving Health • Risk factors in your control: • Smoking • Alcohol intake • Over-consumption of calories • Physical inactivity • Poor quality diet

  32. Improving Health • Risk factors you cannot control: • Age • Gender • Genetics (family history) • Ethnicity

  33. Maine Data • 27% report NO physical activity • 21% engage in moderate physical activity ~5 days/week • 74% do NOT eat 5 servings of fruits and vegetables daily • 56% are overweight or obese • 20% are obese • (2000 data for adults)

  34. Evaluating Nutritional Status (4) Components of evaluating nut. status • Health and diet history • Anthropometric data • Height, weight, … • Physical exam • Hair, skin, eyes…. • Laboratory tests • Cholesterol levels, iron levels…

  35. Evaluating Nutritional Status Personal History • SES • living situation • personal health • family health history • Educational level….. Diet History

  36. Evaluating Nutritional Status Anthropometric data • Height and weight • Waist circumference • % body fat Physical exam • Hair, skin, eyes, tongue… Laboratory Tests • Cholesterol levels • Iron levels

  37. Nutritional Deficiencies • Primary vs. secondary deficiency • Primary – inadequate intake of the nutrient • Secondary – body doesn’t absorb adequate amounts, excretes too much…. • Body “mishandles” the nutrient

  38. Nutritional Deficiencies • Overt vs. covert deficiency • Overt – outward signs of the deficiency • Covert – may be detected by lab tests, but no outward signs of the deficiency • Sub-clinical deficiency

  39. Levels of Nutritional Status • Ideal nutrition • Intake is sufficient to meet daily needs and to keep nutritional stores full while maintaining a healthy body weight

  40. Borderline Nutrition • Intake is sufficient to meet daily needs, but not enough to keep reserves full • Body is not prepared to handle times of stress • Illness, pregnancy… • May slows growth and development of fetus and growing child

  41. Undernutrition • Intake does not meet daily caloric and nutrient needs and nutrient reserves are empty for some/all nutrients • There is a decline in body functions due to the lack of nutrients • Can be life threatening • Medical intervention required

  42. Under-nourished • Populations at increased risk: • anyone living in poverty • especially infants, children, pregnant women, elderly • elderly in general, including those living in nursing homes • pregnant teens • drug and alcohol addicts • individuals with eating disorders • anyone with prolonged illness, including hospital patients

  43. Malnourished • The term malnourished is commonly used in reference to chronic under-nutrition • It can also be used in reference to anyone with chronic poor nutrition that results in failing health

  44. Over-Nutrition • Another form of malnourishment • excessive caloric intake that leads to obesity • Increase risk of obesity related diseases • heart disease, diabetes…. • overuse of vitamin supplements that leads to toxicity symptoms

  45. 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

  46. 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?:

  47. 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?

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

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