Post on 01-Jan-2016
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NUTRITION I & II: METABOLIC AND DIETARY ASPECTS
D. C. MIKULECKYPROFESSOR OF PHYSIOLOGYVIRGINIA COMMONWEALTH
UNIVERSITY
NUTRITION, ENERGY BALANCE AND TEMPERATURE REGULATION
ENERGY SOURCESENERGY METABOLISMREGULATION OF ENERGY
METABOLISMBASAL METABOLIC RATE
ENERGY
THE CAPACITY TO DO WORKTHE 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
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
( )
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
CONTROL OF FOOD INTAKE
POORLY UNDERSTOODOBESITY IS TOO MUCH STORED FATLIPOSTATIC THEORYGI DISTENSION THEORYGLUCOSTATIC THEORYCCK SECRETION THEORYPSYCHOSOCIAL INFLUENCES
GENERAL ADAPTATION SYNDROME
FLIGHT OR FIGHTEPINEPHRINECRH-ACTH-CORTISOLRENIN-ANGIOTENSIN-ALDOSTERONEVASOPRESSINCOORDINATED BY HYPOTHALAMUSCAN BE INDUCED PSYCHOSOCIALLY
ANABOLISM VS CATABOLISM
BUILD UP VS BREAKDOWN OF LARGE MOLECULES
ANABOLISM REQUIRES ENERGY (ATP)
CATABOLISM:ENERGY PRODUCTION
THE ROLE OF VITAMINS AND MINERALS IN METABOLISM
COFACTORS FOR ENZYMES (MOST WATER SOLUABLE VITAMINS)
WATER SOLUABLE VITAMINS
B1 (THIAMINE):
B2 (RIBOFLAVIN) NIACIN C (ASCORBIC ACID) FOLIC ACID B6 ( PYRIDOXINE, PYRIDOXAL,
PYRIDOXAMINE) B12 PANTHOTHENIC ACID BIOTIN
FAT SOLUABLE VITAMINS
ABSORBED ALONG WITH FATSVITAMIN A: PRECURSOR OF
RHODOPSINVITAMIN D: CALCIUM
METABOLISMVITAMIN E : LIPID ANTIOXIDANTVITAMIN K: BLOOD CLOTTING
CONTROL OF FUEL METABOLISM
GLYCOGENESISGLYCOGENOLYSISGLUCONEOGENESISPROTEIN SYNTHESISPROTEIN DEGRADATIONFAT SYNTHESISFAT BREAKDOWN
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
GLYCOGENOLYSIS
BREAKDOWN OF GLYCOGEN STORES INTO GLUCOSE
REGULATES BLOOD GLUCOSE BETWEEN MEALS
HOMONALLY CONTROLLED (GLUCAGON, EPINEHRINE, NOREPINEPHRINE AND CLUCOCORTICOIDS)
GLUCONEOGENESIS
PRUCURSORS ARE 3 AND 4 CARBON COMPOUNDS
VIA FRUCTOSE PHOSPHATEGLUCAGON CONTROLLEDMAIN PRECURSOR ALANINE AND
OTHER AA
PROTEIN DEGRADATION
USUALLY BALANCED BY SYNTHESIS
NO ENERGY STORES IN FORM OF PROTEIN
CAN BE ENHANCED BY GLUCAGON AND OTHER HORMONES LEADING TO GLUCONEOGENESIS
FAT SYNTHESIS
GLUCOSE - FATTY ACID CYCLEFATTY ACIDS PRODUCED
CONSTANTLY IN ADIPOSE TISSUE.
BECOME FFA OR BECOME TRIGLYCERIDES DEPENDING ON -GLYCEROL PHOSPHATE FROM GLUCOSE OXIDATION
GLUCOSE - FATTY ACID CYCLE
FATTYACIDS
TRIGLYCERIDES
CO2
GLUCOSE-6-P
GLUCOSE
FFA
ADIPOCYTE MYOCYTE
KETONES(-)
(-)BLOOD
FAT BREAKDOWN
MOST CONCENTRATED ENERGY STOREONE DAY’S NEEDS CAN BE MET BY LESS
THAN 250g (70kg MAN 40 DAYS)STORED AS TRIGLYCERIDES IN ADIPOSE
TISSUE AND MUSCLEENHANCED BY GLUCAGONTRIGLYCERIDE LIPASEGLYCEROL MUST PASS TO BLOOD TO BE
RECYCLED
BASAL METABOLIC RATE
BODY’S “IDLING SPEED”
DIRECT CALORIMETERY
INDIRECT CALORIMETERY
(SEE LAB NOTES FROM DEC.2)
PROTEIN SYNTHESIS
USUALLY BALANCED WITH BREAKDOWN
INSULIN INCREASES SYNTHESIS
GLUCAGON IS ANTAGONISTIC
ESSENTIAL AMINO ACIDS
VALINETHREONINE ISOLEUCINELEUCINEHISTADINE
(IN INFANTS)
METHIONINE, PHENYLALANINETRYPTOPHANLYSINE
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
PLANTS AND PROTEIN QUALITY
FOOD SOURCE LIMITING AA ABUNDANT AA
WHOLE GRAINS THREONINE METHIONINE,LYSINE
CORN LYSINE,THREONINE,TRYPTOPHAN
OATS, RICE,WHITE FLOUR
LYSINE
LEGUMES SULFUR AA,TRYPTOPHAN
LYSINE,THREONINE
PLANTS AS A PROTEIN SOURCE
65% OF THE PER CAPITA SUPPLY WORLD WIDE
32% OF THE PER CAPITA SUPPLY IN THE US
INCOMPLETE PROTEINS NEEDED TO MEET REQUIREMENTS
2 2/3 CUPS COOKED WHEAT3 CUPS COOKED RICE5 3/4 SLICES BASIC BREAD3 CUPS DICED POTATOES1/3 CUP SOY SPREAD1/2 CUP WHEAT GERM2 3/4 CUPS RICE WITH 1/3 CUP
COOKED PEAS
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
SOME WAYS TO CUT DOWN ON FAT
EAT MORE VEGETARIAN MEALSEAT MORE FRESH FRUIT OR
YOGURT INSTEAD OF DESSERTSUSE YOGURT AS DRESSING
INSTEAD OF OILUSE FRESH HERBS INSTEAD OF
BUTTER (AND INSTEAD OF SALT)
TYPES OF VEGETARIAN DIETS
VEGAN: NO ANIMAL PRODUCTS (NEED DIETARY SUPPLIMENTS AND VARIED PROTEIN SOURCES)
LACTO: +DAIRY PRODUCTS
LACTO-OVO: +EGGS
FIBER
ROUGHLY SPEAKING, EVERYTHING IN PLANT FOODS OUR DIGESTIVE ENZYMES CAN NOT BREAK DOWN
NURTURES AEROBIC BACTERIA IN GUTSOLUABLE FIBER REDUCES INSULIN
NEED IN DIABETICSCHELATORS-INCREASE NEED FOR
MINERALS
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
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
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
PROPOSED MECHANISMS FOR FIBER CANCER PREVENTION
INCREASED FECAL BULK DECREASES CARCINOGEN CONCENTRATION
CHANGE IN FLORASHORTENED TRANSIT TIME
DECREASES CONTACT TIME AND TIME FOR SYNTHESIS OF TOXINS
CHANGE IN pH