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Nutrition

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Nutrition

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Presentation Transcript

  1. Nutrition “Leave your drugs at the chemist’s pot if you can heal your patient with food.” Hippocrates

  2. Introduction to Nutrition Nourishment: • Provision of energy and building materials essential for growth and survival Nutrition: • Study of food and nutrients, their actions, interactions and balance in relation to health and disease • Overall role of nutrition is to supply appropriate substrates to cells of various tissues for moment to moment function

  3. Introduction to Nutrition Nutrient: • a substance that nourishes • macronutrients ( protein, carbohydrate, fats) • micronutrients (vitamins, minerals, trace elements) Essential nutrient: • a nutrient required for survival (species specific) Conditionally essential nutrient • one that may become essential under certain conditions

  4. Nutrients in question include, among other things: • oxidizable energy sources used for production of useful chemical energy carriers such as ATP • amino acids required for protein synthesis, as precursors for purines & pyrimidines and other specialized molecules • vitamins required for a variety of specific cell functions • inorganic compounds such as calcium, phosphorus, iron, etc.

  5. Nutrient Functions • Structural • Muscle, bone, cytoskeletal • Functional • enzymatic reactions, transport, synthesis, degradation, energy metabolism… LIFE! • Chemical • toxicity, pharmacologic properties- includes phytochemicals, “functional foods”

  6. Nutrition and Health and Disease: Evolution of Guidelines • Historically, dietary restrictions were related to religious practices and law. • Late 1800’s: Germ theory of disease: contaminated foods could act as vectors. • Early 1900’s: Vitamin theory of disease: substances missing from diet contributing to disease.

  7. Nutrition and Health and Disease: Evolution of Guidelines • Post WW2: Framingham, Twin Cities, 7 Country studies: evaluated diet and life style risks for development of cardiac disease: • Link between dietary excess and development of chronic disease

  8. Nutrition and Disease • Obesity • Type II diabetes • Atherosclerotic cardiovascular disease • Hypertension • Cancer • Dental carries • Osteoporosis • Anemia • Infection • Pregnancy outcomes • Pediatric growth and development

  9. Nutrition and Disease • Chronic diseases: Diabetes, Cardiovascular disease, Hypertension, Stroke and Cancer • Prevalent: 7 out of 10 who die each year die from chronic disease- more than 1.7 million. • Costly: 75% of the nation’s $1.4 trillion medical care costs. • Preventable

  10. Dietary Reference Intakes

  11. Dietary Reference Intakes (DRI) • Reference values for meeting needs for essential nutrients and energy • Determined by Food and Nutrition Board of the National Academy of Sciences • Firmly established on basis of experimental evidence • Designed to prevent impairment of health from nutritional inadequacy which is directly related to diet and to which susceptibility is universal

  12. RDA - DRI • Defined as the amounts of nutrients considered sufficient to meet the physiological needs of practically all healthy persons in a specific group (age and gender based) and the amount of food sources of energy needed by members of that group • Designed to prevent nutritional deficiencies which lead to specific pathological conditions • Focus now on indicators of nutritional sufficiency and on levels which may prevent chronic disease

  13. RDA/ DRI’s • deal mainly with quantities of micronutrients and protein needed daily • do not deal with non-nutrients and nutrients that are not essential • specific values are given for different age-sex groups • serve as standards for establishing health policy • Terminology - Dietary Reference Intake (DRI) has “replaced” the term RDA in United States & Canada

  14. DRI includes • Estimated Average Requirement (EAR) - intake at which risk of inadequacy is 50% (EAR is evidence-based) • Recommended Dietary Allowance (RDA) - intake at which risk of inadequacy is 2 - 3% • RDA set relative to EAR: RDA = EAR + 2SDEAR • Tolerable Upper Limit (UL) - highest level of daily intake likely to pose no risks of adverse effect to almost all persons in general population • Adequate Intake (AI) - set for those nutrients without enough evidence to develop RDA, no consistent relationship to EAR or RDA

  15. DRI Example: Calcium • Infant 0-6 months: 210 mg • Infant 6-12 months: 210 mg • Child 1-3 y: 500 mg • Child 4-8 y: 800 mg • Males/Females 9-13, 14-18 1300 mg • Males/Females 19-30, 31-50 1000 mg • Males/Females 51-70, >70 1200 mg • Pregnancy same as age group • Lactation same as age group

  16. New Macronutrient Guidelines and DRI’s announced recently (Sept. 2002) For ages >19 years old (% of total calories) • Carbohydrates: 45 - 65% • Fats: 25 - 35% • Protein: 10 - 35% • Fiber: 25-38 g per day • Essential fatty acids: w-3’s new • Increased exercise recommended: • 60 minutes per day of moderate activity for children and adults

  17. DRI’s and Food Labels • Daily Values for nutrients listed on food labels as required by FDA • Reference Daily Intake for vitamins and minerals • Uses RDA’s for 18 y/o male (highest RDA) except for iron (19-30 y/o female)

  18. Dietary Guidelines

  19. Dietary Guidelines • Differ from DRI in several aspects • Much more general than DRI • Primarily deal with quantities of certain foods and nonessenteial dietary components (e.g., fiber, cholesterol, saturated fat, etc.) and proportions and types of energy sources judged desirable in healthful diets

  20. Dietary Guidelines • advice on selecting foods to achieve nutritionally adequate diet • deal mainly with proportions of energy-yielding nutrients in diet • include advice on consumption of such non-nutrients as fiber and cholesterol • recommendations are general, without specification for different segments of the population

  21. Dietary Guidelines • are health policy proposals • directed toward prevention of chronic diseases for which diet is a potential modifying factor and to which susceptibility is highly variable • evidence mainly indirect from observations between diet and disease incidence

  22. Consensus Dietary GuidelinesCirculation 100:450 (1999) • The Unified Dietary Guidelines: American Cancer Society, American Dietetic Association, American Academy of Pediatrics, National Institutes of Health and American Heart Association.

  23. Consensus Dietary GuidelinesCirculation 100:450 (1999) • Saturated fat < 10% of calories • Total fat < 30% of calories • Polyunsaturated fat < 10% of calories • Monounsaturated fat < 15% of calories • Cholesterol < 300 mg/day • Carbohydrates > 55% of calories • Total calories to achieve and maintain desirable weight • Salt intake limited to < 6 g/day

  24. Consensus Dietary GuidelinesCirculation 100:450 (1999) • The consensus panel concluded that for many individuals the recommendations could best be achieved by following U. S. Dietary Guidelines and Food Guide Pyramid

  25. USDA Food Guide Pyramid

  26. Nutrition and Your Health:Dietary Guidelines for AmericansUSDA & USDHHS 5th ed., May 2000

  27. Aim for Fitness • Aim for a healthy weight • Be physically active Build a Healthy Base • Let the Pyramid guide your food choices • Choose a variety of grains daily, especially whole grains • Choose a variety of fruits and vegetables daily • Keep food safe to eat

  28. Choose Sensibly • Choose a diet that is low in saturated fat and cholesterol and moderate in total fat • Choose beverages and foods to moderate your intake of sugars • Choose and prepare foods with less salts • If you drink alcoholic beverages, do so in moderation

  29. Criticism of USDA Food Guide Pyramid

  30. Willet Food Guide Pyramid

  31. Revision of Food Guide Pyramid • Currently underway, expected 2005 • Areas expected to be addressed • Portion sizes: are currently not consistent with portion sizes typically consumed or stated on food labels as required by FDA • Most problematic with grains/starches • Pyramid suggests 6-11 servings per day, counting 1 serving as 1/2 small bagel

  32. How are we eating?

  33. A few comments on Obesity and Comorbidities

  34. A few comments on obesity • The most serious nutritional problem in the United States and the industrialized world is the marked increase in obesity • The problem is extending to less developed countries. • It is growing at epidemic rates in adult populations • Also occurring at alarming rates in children

  35. Notes: *For adults Overweight includes Obese & Extremely obese ¶All values for children are for Overweight For 1976 - 1980, 47% of adults were overweight (15% were obese)

  36. Obesity and comorbidity risk

  37. U.S. NIH revised weight guidelines: 1994 and 1998 • Guidelines apply equally to men & women • Guidelines do NOT allow for weight gain in middle age • Revisions made in response to mounting evidence that increases in weight associated with increased risk of premature death from heart disease, diabetes, and certain cancers

  38. At each height, proposed guidelines recommend weights that translate to a Body Mass Index (BMI) of 18.9 - 24.9 • In medical literature, BMI is calculated by BMI = Weight(kg)/[Height(m)]2 • Current research suggests that obesity-related health problems begin to mount at BMIs above 25

  39. U. S. National Institutes of Health obesity guidelines (June, 1998) • BMI • Underweight < 18.5 • Normal 18.5 - 24.9 • Overweight 25 - 29.9 • Obese (Class I) 30 - 34.9 • Obese (Class II) 35 - 39.9 • Obese (Class III) > 40

  40. In this unisex version: • weights at lower end of range recommended for persons with low ratio of bone to fat • weights at upper end of range advised for those with more muscular physiques • most of us fall into the 1st category, thus DHHS-NIH suggest that we aim for lower end of range

  41. Conversion factors: • Weight (lb) x 0.454 kg/lb = Weight (kg) • Height (in)/39.4 = Height (m)

  42. Conflicting Nutritional Advice

  43. Nutrition Recommendations • Nutrition science is a rapidly growing field of study, many new and sometimes conflicting findings and advice reported in popular press. • “Guidelines” often influenced by special interest groups. • Consumer behavior is greatly influenced by multi-billion dollar food industry.

  44. Recent info on consumer confusion and negativism about nutritional advice • J. Am. Dietitics Assoc (01/01/01) Reported survey results on conflicting advice about “healthy diet” • >40% were tired of hearing about foods they should or should not eat • ~40% thought that dietary guidelines be taken with “a grain of salt” • 70% said government shouldn’t tell people what to eat