Introduction to Human Nutrition

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

40. 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

41. 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

42. 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

43. 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

44. 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

45. 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

46. 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

48. 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?:

49. 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?

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