NUTRITION I

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NUTRITION I II METABOLIC AND DIETARY ASPECTS

• D. C. MIKULECKY
• PROFESSOR OF PHYSIOLOGY
• VIRGINIA COMMONWEALTH UNIVERSITY

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NUTRITION, ENERGY BALANCE AND TEMPERATURE
REGULATION

• ENERGY SOURCES
• ENERGY METABOLISM
• REGULATION OF ENERGY METABOLISM
• BASAL METABOLIC RATE

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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

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ENERGY BALANCE WITH RESPECT TO THE BODY
INPUT - OUTPUT STORAGE OR DEPLETION (CONTINUI
TY EQUATION ?E/?t ?2E)
(
)
OUTPUT INTERNAL WORK EXTERNAL WORK
INTERNAL WORK ------ HEAT
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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

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FOOD AS STORED FUEL

• 3500 CALORIES 1 LB OF BODY MASS

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ENERGY INPUT

• 50 GOES TO ATP
• 50 GOES TO HEAT
• CARBOHYDRATE, FAT AND PROTEIN

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FOOD AS FUEL

• CARBOHYDRATE 4 CAL/G
• PROTEIN 4 CAL/G
• FAT 9 CAL/GRAM
• ETHANOL 7 CAL/G

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FOOD INTAKE

• CONTROLED BY HYPOTHALAMUS
• FEEDING CENTERS
• SATIETY CENTERS

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CONTROL OF FOOD INTAKE

• POORLY UNDERSTOOD
• OBESITY IS TOO MUCH STORED FAT
• LIPOSTATIC THEORY
• GI DISTENSION THEORY
• GLUCOSTATIC THEORY
• CCK SECRETION THEORY
• PSYCHOSOCIAL INFLUENCES

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FOOD AS STORED FUEL

• 3500 CALORIES 1 LB OF BODY MASS

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THE METABOLIC RATE
METABOLIC RATE ENERGY EXPENDITURE PER UNIT
TIME (Calories/hour)
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FACTORS INFLUENCING METABOLIC RATE

• EXERCISE
• FOOD INTAKE
• SHIVERING
• ANXIETY

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GENERAL ADAPTATION SYNDROME

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

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ANABOLISM VS CATABOLISM

• BUILD UP VS BREAKDOWN OF LARGE MOLECULES
• ANABOLISM REQUIRES ENERGY (ATP)
• CATABOLISMENERGY PRODUCTION

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THE ROLE OF VITAMINS AND MINERALS IN METABOLISM

• COFACTORS FOR ENZYMES (MOST WATER SOLUABLE
  VITAMINS)

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WATER SOLUABLE VITAMINS

• B1 (THIAMINE)
• B2 (RIBOFLAVIN)
• NIACIN
• C (ASCORBIC ACID)
• FOLIC ACID
• B6 ( PYRIDOXINE, PYRIDOXAL,
  PYRIDOXAMINE)
• B12
• PANTHOTHENIC ACID
• BIOTIN

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FAT SOLUABLE VITAMINS

• ABSORBED ALONG WITH FATS
• VITAMIN A PRECURSOR OF RHODOPSIN
• VITAMIN D CALCIUM METABOLISM
• VITAMIN E LIPID ANTIOXIDANT
• VITAMIN K BLOOD CLOTTING

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CONTROL OF FUEL METABOLISM

• GLYCOGENESIS
• GLYCOGENOLYSIS
• GLUCONEOGENESIS
• PROTEIN SYNTHESIS
• PROTEIN DEGRADATION
• FAT SYNTHESIS
• FAT BREAKDOWN

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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

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GLYCOGENOLYSIS

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

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GLUCONEOGENESIS

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

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PROTEIN DEGRADATION

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

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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

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

• MOST CONCENTRATED ENERGY STORE
• ONE DAYS 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

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BASAL METABOLIC RATE

• BODYS IDLING SPEED
• DIRECT CALORIMETERY
• INDIRECT CALORIMETERY
• (SEE LAB NOTES FROM DEC.2)

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PROTEIN SYNTHESIS

• USUALLY BALANCED WITH BREAKDOWN
• INSULIN INCREASES SYNTHESIS
• GLUCAGON IS ANTAGONISTIC

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ESSENTIAL AMINO ACIDS

• VALINE
• THREONINE
• ISOLEUCINE
• LEUCINE
• HISTADINE (IN INFANTS)

• METHIONINE,
• PHENYLALANINE
• TRYPTOPHAN
• LYSINE

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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

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PLANTS AND PROTEIN QUALITY
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PLANTS AS A PROTEIN SOURCE

• 65 OF THE PER CAPITA SUPPLY WORLD WIDE
• 32 OF THE PER CAPITA SUPPLY IN THE US

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PROTEIN SOURCES-EXCEPTIONS

• SOYBEANS
• QUINONA
• SPINACH
• HAVE THE SAME QUALITY AS MILK

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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

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SOME DISEASES LINKED WITH DIET

• CANCER
• HEART DISEASE
• HIGH BLOOD PRESSURE
• OBESITY
• DIVERTICULITIS

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FOOD INGREDIENTS AND DISEASE

• REFINED SUGAR
• FAT
• SALT
• LOW IN FIBER

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CANCER AND DIET PHYTOCHEMICALS

• FOUND ONLY IN PLANTS
• IMMUNE FUNCTION
• HORMONE BALANCE
• DETOXIFICATION

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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

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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)

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TYPES OF VEGETARIAN DIETS

• VEGAN NO ANIMAL PRODUCTS (NEED DIETARY
  SUPPLIMENTS AND VARIED PROTEIN SOURCES)
• LACTO DAIRY PRODUCTS
• LACTO-OVO EGGS

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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

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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

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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

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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

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SOURCES OF FIBER

• LEGUMES (ALSO PROTEIN SOURCE)
• FRUITS AND VEGETABLES
• WHOLE GRAIN CEREALS AND FLOURS

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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

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CHELATORS LOWER MINERAL ABSORPTION

• PHYTATES
• OXALATES