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

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 UNDERSTOODOBESITY IS TOO MUCH STORED FATLIPOSTATIC THEORYGI DISTENSION THEORYGLUCOSTATIC THEORYCCK SECRETION THEORYPSYCHOSOCIAL 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 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

PROTEIN SOURCES-EXCEPTIONS

SOYBEANS

QUINONA

SPINACH

HAVE THE SAME QUALITY AS MILK

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

SOME DISEASES LINKED WITH DIET

CANCERHEART DISEASEHIGH BLOOD PRESSUREOBESITYDIVERTICULITIS

FOOD INGREDIENTS AND DISEASE

REFINED SUGARFATSALTLOW IN FIBER

CANCER AND DIET: PHYTOCHEMICALS

FOUND ONLY IN PLANTSIMMUNE FUNCTIONHORMONE BALANCEDETOXIFICATION

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

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 FLORASHORTENED TRANSIT TIME

DECREASES CONTACT TIME AND TIME FOR SYNTHESIS OF TOXINS

CHANGE IN pH

CHELATORS LOWER MINERAL ABSORPTION

PHYTATES

OXALATES