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NUTRITION I & II: METABOLIC
AND DIETARY ASPECTS
D. C. MIKULECKY
PROFESSOR OF PHYSIOLOGY
VIRGINIA COMMONWEALTH
UNIVERSITY
NUTRITION, ENERGY BALANCE AND
TEMPERATURE REGULATION
ENERGY SOURCES
ENERGY METABOLISM
REGULATION OF ENERGY
METABOLISM
BASAL METABOLIC RATE
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
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
FOOD AS STORED FUEL
3500 CALORIES =
1 LB OF BODY MASS
ENERGY INPUT
50% GOES TO ATP
50% GOES TO HEAT
CARBOHYDRATE, FAT AND PROTEIN
FOOD AS FUEL
CARBOHYDRATE 4 CAL/G
PROTEIN 4 CAL/G
FAT 9 CAL/GRAM
ETHANOL 7 CAL/G
FOOD INTAKE
CONTROLED BY HYPOTHALAMUS
FEEDING CENTERS
SATIETY CENTERS
CONTROL OF FOOD
INTAKE
POORLY UNDERSTOOD
OBESITY IS TOO MUCH STORED FAT
LIPOSTATIC THEORY
GI DISTENSION THEORY
GLUCOSTATIC THEORY
CCK SECRETION THEORY
PSYCHOSOCIAL INFLUENCES
FOOD AS STORED FUEL
3500 CALORIES =
1 LB OF BODY MASS
THE METABOLIC RATE
METABOLIC RATE =
ENERGY EXPENDITURE PER UNIT TIME
(Calories/hour)
FACTORS INFLUENCING
METABOLIC RATE
EXERCISE
FOOD INTAKE
SHIVERING
ANXIETY
GENERAL ADAPTATION
SYNDROME
FLIGHT OR FIGHT
EPINEPHRINE
CRH-ACTH-CORTISOL
RENIN-ANGIOTENSIN-ALDOSTERONE
VASOPRESSIN
COORDINATED BY HYPOTHALAMUS
CAN 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 FATS
VITAMIN A: PRECURSOR OF
RHODOPSIN
VITAMIN D: CALCIUM METABOLISM
VITAMIN E : LIPID ANTIOXIDANT
VITAMIN K: BLOOD CLOTTING
CONTROL OF FUEL
METABOLISM
GLYCOGENESIS
GLYCOGENOLYSIS
GLUCONEOGENESIS
PROTEIN SYNTHESIS
PROTEIN DEGRADATION
FAT SYNTHESIS
FAT 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 PHOSPHATE
GLUCAGON CONTROLLED
MAIN 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 CYCLE
FATTY ACIDS PRODUCED
CONSTANTLY IN ADIPOSE TISSUE.
BECOME FFA OR BECOME
TRIGLYCERIDES DEPENDING ON GLYCEROL PHOSPHATE FROM
GLUCOSE OXIDATION
GLUCOSE - FATTY ACID
CYCLE
ADIPOCYTE
MYOCYTE
FFA
FATTY
ACIDS
KETONES
(-)
CO2
(-)
BLOOD
GLUCOSE-6-P
TRIGLYCERIDES
GLUCOSE
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
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
VALINE
THREONINE
ISOLEUCINE
LEUCINE
HISTADINE
(IN INFANTS)
METHIONINE,
PHENYLALANINE
TRYPTOPHAN
LYSINE
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
LYSINE
,
OATS, RICE
WHITE FLOUR
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
PROTEIN SOURCES-EXCEPTIONS
SOYBEANS
QUINONA
SPINACH
HAVE THE SAME QUALITY AS MILK
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
SOME DISEASES LINKED WITH DIET
CANCER
HEART DISEASE
HIGH BLOOD PRESSURE
OBESITY
DIVERTICULITIS
FOOD INGREDIENTS AND
DISEASE
REFINED SUGAR
FAT
SALT
LOW IN FIBER
CANCER AND DIET:
PHYTOCHEMICALS
FOUND ONLY IN PLANTS
IMMUNE FUNCTION
HORMONE BALANCE
DETOXIFICATION
CANCER AND DIET N.R.C.RECOMMENDATIONS
EAT LESS FAT (30% OR LESS 0F TOTAL
CALORIES)
EAT FRUITS, VEGITABLES, AND WHOLEGRAIN 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 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)
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 GUT
SOLUABLE FIBER REDUCES INSULIN NEED
IN DIABETICS
CHELATORS-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 DIETIMPLICATED CANCER 35-40 g/day
DIABETICS UP TO 50 g/day
SOURCES OF FIBER
LEGUMES (ALSO PROTEIN SOURCE)
FRUITS AND VEGETABLES
WHOLE GRAIN CEREALS AND
FLOURS
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
CHELATORS LOWER MINERAL ABSORPTION
PHYTATES
OXALATES