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NUTRITION I & II: METABOLIC AND DIETARY ASPECTS
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NUTRITION I & II: METABOLIC AND DIETARY ASPECTS

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  1. NUTRITION I & II: METABOLIC AND DIETARY ASPECTS D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY VIRGINIA COMMONWEALTH UNIVERSITY

  2. NUTRITION, ENERGY BALANCE AND TEMPERATURE REGULATION • ENERGY SOURCES • ENERGY METABOLISM • REGULATION OF ENERGY METABOLISM • BASAL METABOLIC RATE

  3. ENERGY • THE CAPACITY TO DO WORK • THE CALORIE IS THE AMMOUNT OF HEAT ENERGY NECESSARY TO RAISE THE TEMPERATURE OF 1 GRAM OF WATER 1 DEGREE CENTIGRADE • THE NUTRITIONAL CALORIE IS 1000 CALORIES OR THE KILOCALORIE

  4. ENERGY BALANCE WITH RESPECT TO THE BODY INPUT - OUTPUT = STORAGE OR DEPLETION (CONTINUITY EQUATION E/t = 2E) ( ) OUTPUT = INTERNAL WORK + EXTERNAL WORK INTERNAL WORK ------> HEAT

  5. STORAGE AND/OR DEPLETION • NUETRAL ENERGY BALANCE OCCURS WHEN INPUT AND OUTPUT MATCH • POSITIVE ENERGY BALANCE OCCURS WHEN INTAKE EXCEEDS OUTPUT - ENERGY IS STORED AS GLYCOGEN OR FAT • NEGATIVE ENERGY BALANCE OCCURS WHEN OUTPUT EXCEEDS INTAKE- ENERGY STORES ARE DEPLETED

  6. FOOD AS STORED FUEL • 3500 CALORIES = 1 LB OF BODY MASS

  7. ENERGY INPUT • 50% GOES TO ATP • 50% GOES TO HEAT • CARBOHYDRATE, FAT AND PROTEIN

  8. FOOD AS FUEL • CARBOHYDRATE 4 CAL/G • PROTEIN 4 CAL/G • FAT 9 CAL/GRAM • ETHANOL 7 CAL/G

  9. FOOD INTAKE • CONTROLED BY HYPOTHALAMUS • FEEDING CENTERS • SATIETY CENTERS

  10. CONTROL OF FOOD INTAKE • POORLY UNDERSTOOD • OBESITY IS TOO MUCH STORED FAT • LIPOSTATIC THEORY • GI DISTENSION THEORY • GLUCOSTATIC THEORY • CCK SECRETION THEORY • PSYCHOSOCIAL INFLUENCES

  11. FOOD AS STORED FUEL • 3500 CALORIES = 1 LB OF BODY MASS

  12. THE METABOLIC RATE METABOLIC RATE = ENERGY EXPENDITURE PER UNIT TIME (Calories/hour)

  13. FACTORS INFLUENCING METABOLIC RATE • EXERCISE • FOOD INTAKE • SHIVERING • ANXIETY

  14. GENERAL ADAPTATION SYNDROME • FLIGHT OR FIGHT • EPINEPHRINE • CRH-ACTH-CORTISOL • RENIN-ANGIOTENSIN-ALDOSTERONE • VASOPRESSIN • COORDINATED BY HYPOTHALAMUS • CAN BE INDUCED PSYCHOSOCIALLY

  15. ANABOLISM VS CATABOLISM • BUILD UP VS BREAKDOWN OF LARGE MOLECULES • ANABOLISM REQUIRES ENERGY (ATP) • CATABOLISM:ENERGY PRODUCTION

  16. THE ROLE OF VITAMINS AND MINERALS IN METABOLISM • COFACTORS FOR ENZYMES (MOST WATER SOLUABLE VITAMINS)

  17. WATER SOLUABLE VITAMINS • B1 (THIAMINE): • B2 (RIBOFLAVIN) • NIACIN • C (ASCORBIC ACID) • FOLIC ACID • B6 ( PYRIDOXINE, PYRIDOXAL, PYRIDOXAMINE) • B12 • PANTHOTHENIC ACID • BIOTIN

  18. FAT SOLUABLE VITAMINS • ABSORBED ALONG WITH FATS • VITAMIN A: PRECURSOR OF RHODOPSIN • VITAMIN D: CALCIUM METABOLISM • VITAMIN E : LIPID ANTIOXIDANT • VITAMIN K: BLOOD CLOTTING

  19. CONTROL OF FUEL METABOLISM • GLYCOGENESIS • GLYCOGENOLYSIS • GLUCONEOGENESIS • PROTEIN SYNTHESIS • PROTEIN DEGRADATION • FAT SYNTHESIS • FAT BREAKDOWN

  20. GLYCOGENESIS • GLYCOGEN IS A BRANCHED POLYMER OF GLUCOSE ATORED IN THE LIVER (ABOUT 100g) AND MUSCLE CELLS(ABOUT 200g). ENOUGH FOR PART OF A DAY. • SYNTHESIS IS BY SEPARATE PATHWAY FROM BREAKDOWN • HIGHLY REGULATED BY INSULIN

  21. GLYCOGENOLYSIS • BREAKDOWN OF GLYCOGEN STORES INTO GLUCOSE • REGULATES BLOOD GLUCOSE BETWEEN MEALS • HOMONALLY CONTROLLED (GLUCAGON, EPINEHRINE, NOREPINEPHRINE AND CLUCOCORTICOIDS)

  22. GLUCONEOGENESIS • PRUCURSORS ARE 3 AND 4 CARBON COMPOUNDS • VIA FRUCTOSE PHOSPHATE • GLUCAGON CONTROLLED • MAIN PRECURSOR ALANINE AND OTHER AA

  23. PROTEIN DEGRADATION • USUALLY BALANCED BY SYNTHESIS • NO ENERGY STORES IN FORM OF PROTEIN • CAN BE ENHANCED BY GLUCAGON AND OTHER HORMONES LEADING TO GLUCONEOGENESIS

  24. FAT SYNTHESIS • GLUCOSE - FATTY ACID CYCLE • FATTY ACIDS PRODUCED CONSTANTLY IN ADIPOSE TISSUE. • BECOME FFA OR BECOME TRIGLYCERIDES DEPENDING ON -GLYCEROL PHOSPHATE FROM GLUCOSE OXIDATION

  25. GLUCOSE - FATTY ACID CYCLE ADIPOCYTE MYOCYTE FFA CO2 FATTY ACIDS (-) KETONES BLOOD (-) GLUCOSE-6-P TRIGLYCERIDES GLUCOSE

  26. FAT BREAKDOWN • MOST CONCENTRATED ENERGY STORE • ONE DAY’S NEEDS CAN BE MET BY LESS THAN 250g (70kg MAN 40 DAYS) • STORED AS TRIGLYCERIDES IN ADIPOSE TISSUE AND MUSCLE • ENHANCED BY GLUCAGON • TRIGLYCERIDE LIPASE • GLYCEROL MUST PASS TO BLOOD TO BE RECYCLED

  27. BASAL METABOLIC RATE • BODY’S “IDLING SPEED” • DIRECT CALORIMETERY • INDIRECT CALORIMETERY • (SEE LAB NOTES FROM DEC.2)

  28. PROTEIN SYNTHESIS • USUALLY BALANCED WITH BREAKDOWN • INSULIN INCREASES SYNTHESIS • GLUCAGON IS ANTAGONISTIC

  29. VALINE THREONINE ISOLEUCINE LEUCINE HISTADINE (IN INFANTS) METHIONINE, PHENYLALANINE TRYPTOPHAN LYSINE ESSENTIAL AMINO ACIDS

  30. PROTEIN QUALITY • ONLY 20% OF THE RDA NEEDS TO BE COMPLETE PROTEIN (11 GRAMS FOR MALES 9 GRAMS FOR FEMALES …A LITTLE MORE THAN SUPPLIED BY A GLASS OF MILK) • MORE DIVERSITY IS THE KEY THOUGH: 60% RDA FROM GRAIN, 35% FROM LEGUMES, 5% FROM GREEN LEAFY VEGETABLES

  31. PLANTS AND PROTEIN QUALITY

  32. PLANTS AS A PROTEIN SOURCE • 65% OF THE PER CAPITA SUPPLY WORLD WIDE • 32% OF THE PER CAPITA SUPPLY IN THE US

  33. PROTEIN SOURCES-EXCEPTIONS • SOYBEANS • QUINONA • SPINACH • HAVE THE SAME QUALITY AS MILK

  34. INCOMPLETE PROTEINS NEEDED TO MEET REQUIREMENTS • 2 2/3 CUPS COOKED WHEAT • 3 CUPS COOKED RICE • 5 3/4 SLICES BASIC BREAD • 3 CUPS DICED POTATOES • 1/3 CUP SOY SPREAD • 1/2 CUP WHEAT GERM • 2 3/4 CUPS RICE WITH 1/3 CUP COOKED PEAS

  35. SOME DISEASES LINKED WITH DIET • CANCER • HEART DISEASE • HIGH BLOOD PRESSURE • OBESITY • DIVERTICULITIS

  36. FOOD INGREDIENTS AND DISEASE • REFINED SUGAR • FAT • SALT • LOW IN FIBER

  37. CANCER AND DIET: PHYTOCHEMICALS • FOUND ONLY IN PLANTS • IMMUNE FUNCTION • HORMONE BALANCE • DETOXIFICATION

  38. CANCER AND DIET N.R.C.RECOMMENDATIONS • EAT LESS FAT (30% OR LESS 0F TOTAL CALORIES) • EAT FRUITS, VEGITABLES, AND WHOLE-GRAIN CEREAL FOODS EVERY DAY (ESPECIALLY THOSE HIGH IN VITAMINS A AND C) • AVOID HIGH DOSE SUPPLIMENTS OF VITAMINS OR OTHER NUTRIENTS • ALCOHOL ONLY IN MODERATION

  39. SOME WAYS TO CUT DOWN ON FAT • EAT MORE VEGETARIAN MEALS • EAT MORE FRESH FRUIT OR YOGURT INSTEAD OF DESSERTS • USE YOGURT AS DRESSING INSTEAD OF OIL • USE FRESH HERBS INSTEAD OF BUTTER (AND INSTEAD OF SALT)

  40. TYPES OF VEGETARIAN DIETS • VEGAN: NO ANIMAL PRODUCTS (NEED DIETARY SUPPLIMENTS AND VARIED PROTEIN SOURCES) • LACTO: +DAIRY PRODUCTS • LACTO-OVO: +EGGS

  41. FIBER • ROUGHLY SPEAKING, EVERYTHING IN PLANT FOODS OUR DIGESTIVE ENZYMES CAN NOT BREAK DOWN • NURTURES AEROBIC BACTERIA IN GUT • SOLUABLE FIBER REDUCES INSULIN NEED IN DIABETICS • CHELATORS-INCREASE NEED FOR MINERALS

  42. TYPES OF FIBER • PECTINS: IN CELL WALL OF FRUITS, BIND BILE SALTS • GUMS: STICKY SUBSTANCES EXUDED BY PLANTS, LOWER CHOLESTEROL UPTAKE AND SLOW SUGAR ABSORPTION • CELLULOSE: PLANT CELL WALLS, BULK AND TOXIN ELIMINATION • HEMICELLULOSES: PLANT CELL WALLS, BULK • LIGNIN: ROOT VEGETABLES, BULK

  43. EFFECT ON MICROFLORA • LOWER TOTAL ANAEROBIC, IN PARTICULAR, CLOSTRIDIUM • DIET CAN ALTER THE METABOLIC ACTIVITY OF THE FLORA • MEAT AND UNREFINED SUGAR INCREASES UNWANTED BACTERIA • VEGETARIAN DIET LOWERS RISKS OF BOWEL CANCER

  44. RECOMMENDED FIBER INTAKE • 20 - 25 g/day WITH AN UPPER LIMIT OF 35 g/day • FAMILY HISTORY OF DIET-IMPLICATED CANCER 35-40 g/day • DIABETICS UP TO 50 g/day

  45. SOURCES OF FIBER • LEGUMES (ALSO PROTEIN SOURCE) • FRUITS AND VEGETABLES • WHOLE GRAIN CEREALS AND FLOURS

  46. PROPOSED MECHANISMS FOR FIBER CANCER PREVENTION • INCREASED FECAL BULK DECREASES CARCINOGEN CONCENTRATION • CHANGE IN FLORA • SHORTENED TRANSIT TIME DECREASES CONTACT TIME AND TIME FOR SYNTHESIS OF TOXINS • CHANGE IN pH

  47. CHELATORS LOWER MINERAL ABSORPTION • PHYTATES • OXALATES