Lecture Vitamins

8/3/2019 Lecture Vitamins

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from vita meaning life

organic compounds that are essential insmall amounts for body process

do not provide energy


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Fat-soluble vitamins

Vitamin A Vitamin D

Vitamin E

Vitamin KWater-soluble vitamins

Vitamin B complex

Thiamin or B1 Folate

Riboflavin or B2 Vit B12(cobalamin)

Niacin Pantothenic acid

Vitamin B6 Biotin

Vitamin C (ascorbic acid)


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avitaminosis : without vitamins

hypervitaminosis : excess of one or more

vitamins vitamin supplements : vitamins taken in

addition to those received in the diet

natural or synthetic

synthetic maybe in tablet or liquid form


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True or false? natural vitaminsare better than synthetic ones

False. The body cannot distinguish thatcoming animals or plants nor that made inthe laboratory. Once in the body, theyhave been dismantled in the digestive

system


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Fortified

terminology for products with addedvitamins during processing; also called

enriched examples are breads and cereals enriched

with thiamin, niacin, riboflavin, folate andiron

milk and fortified margarine fortified withvitamins A & D


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Preserving vitamin content in

food

buy fresh, unbruised fruits and vegetablesand use in raw form whenever possible

prepare fruits and vegetables just beforeserving

heat canned vegetables quickly and in

their own liquid follow package directions when using

frozen vegetables or fruits


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use as little water as possible when

cooking and boil it before addingvegetables; or steam them

cover pan (except for the first fewminutes when cooking strongly flavoredvegetables such as broccoli andcauliflower) and cooking as short time aspossible

save cooking for later use in soups, stew,and gravies

store fresh vegetables and most fruits in a

cool, dark place


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Classification of vitamins

Fat-soluble : A, D, E, K

vitamin D - sometimes classified as ahormone

water soluble : B complex, ascorbic acid

vitamin B complex - sometimes classified ascatalysts or coenzumes

precursors or provitamins - substance fromwhich a the body can synthesize(manufacture) a specific vitamin; ex,carotenoids


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Fat-soluble vitamins

not lost to heat in cooking but lost whenmineral oil is ingested

mineral oil - not absorbed by humans; maybeused in salad dressing to avoid kcal ofvegetable oils; sometimes used as laxative;use should be discouraged as it carries fatsoluble vitamins

transported by lipoproteins excess amount stored in the liver;

deficiencies slower to appear

avoid megadoses


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Vitamin A

one of the antioxidant vitamins that

protects cells from destruction by oxygen oxygen causes free radicals to form which

damage cell structure and function which maycontribute to some cancers and heart disease

free radicals are highly reactive chemicalcompounds that damage other compounds


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Vitamin A

Three forms of vitamin A retinol - major transport and storage of vitamin A

retinal

retinaldehyde transported in the blood by retinol binding

protein (RBP)

Vitamin A in vision : as light enters the eye, pigments within the cells of theretina absorb the light and generate nerve impulsesthat travel to the brain. Each pigment contains retinal,the active form of vitamin A


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Vitamin A

When vitamin A is lacking, the eye has difficultyadapting to changing light levels; at night a lag occursbefore the eye can see again after a flash of bright

light; this lag in the recovery of night vision is callednight blindness; it is , however only a symptom andmay indicate a condition other than vit A deficiency

Vit A in reproduction and growth

in men, vit A participates in sperm development; inwomen, promotes normal fetal growth & development


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Beta- carotone:as anti-oxidant (phytochemical)

beta carotene prevents some cancers

phytochemicals are nonnutrient compounds foundplant-derived foods that have biological activity inthe body

Integrity of epithelial cells

in vitamin A deficiency, epithelial cells flatten andproduce keratin, which leads to drying of corneaand may progress to blindness


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Sources and actions of phytochemicals

Source Name ActionDeeply pigmented frts &veg Carotenoids;lyc antioxidant;reduce cancer risk

Citrus fruits Limonene enzyme to excrete carcinogen

Phenols inhibit lipid oxidation; blockformation of carcinogenic

nitrosamines

Garlic, onion, leek, chives Allyl sulfides trigger enzyme for carcinogenexcretion

Broccoli, sprouts, cruciferous Sulforaphane protects against cancer

(cauliflower,cabbage, kale, Dithiolthiones trigger enzyme to blockbrussel sprouts) carcinogen damage

Indoles trigger enzyme to inhibit estrogen action;red breast

cancer risk

Isothiocyanates enzyme to block carcinogendamage to cells


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Sources and actions of phytochemicalsSource Name Action

Grapes Ellagic acid scavenges carcinogens

Soy / legumes Protease inhibitors suppress enzymeactivity;slows tumor growth

Phytosterols inhibit cell reproduction;prevents colon cancer

Isoflavones block estrogen activity;reducebreast & ovarian cancer

Saponins prevent c cell multiplication

Flaxseed Lignans block estrogen activity

Fruits (Blueberries, Caffeic acid triggers enzyme prod to make

prunes,grapes) oats carcinogens water solublesoybeans to facilitate excretion

Grains Phytic acid binds minerals, preventing

free radical formation

Fruits, veg, tea, Flavonoids (incl antioxidants, reduce cancer

wine, oregano quercetin) and heart disease


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Vitamin A

Infection proneness

flattening and hardness of epithelial cells in

vitamin A deficiency reduces mucus secretionwhich makes it prone to infections (VAD andmeasles or pneumonia); in the digestive tract, itcan hinder digestion and absorption of nutrients

(VAD and diarrhea)


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maintains healthy eyes and skin

for normal growth and reproduction

for healthy immune system aids in the prevention of infections by

helping to maintain healthy mucusmembranes (lining of nose and throat, GIand genito-urinary tract)


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Sources

Provitamin A or beta carotene - found indark green leafy and yellow vegetablesand fruits, ie carrots, kangkong,malunggay, squash, tiesa, mango

eating five a day of fruits and vegetables

consumption of carotenoid rich foods shownby research to decrease risk of some cancers;but taking beta carotene has not shown thesame results

Preformed vitamin A (retinol) : liver,butter, cream, whole milk and cheese,

egg yolk


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What is the Golden Rice ?

variety of rice developed that has theability to produce beta carotene

potential source of beta carotene that willhelp reduce vitamin A deficiency indeveloping countries


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Requirement

expressed as Retinol Equivalent (RE) - 1g retinol or 12 g beta carotene

see RENI

from well balanced diet


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Hypervitaminosis

due to excess intake of vitamin A; signsinclude birth defects, hair loss, dry skin,

headache, nausea, dryness of mucusmembranes; signs and symptomsdisappear after discontinued intake;

excess intake should be discouraged


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Beta carotene conversion

expressed as Retinol Equivalent (RE);earlier used was IU

1 RE =3.33 IU form animal foods or 10 IUfrom plant foods (average of1 RE=5 IU)


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Deficiency

xerophthalmia - serious eye diseasecharacterized by lack of luster of the eyes,

may lead to blindness nightblindness

dry skin

susceptibility to infection


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Vitamin D

7 -dehydrocholecalciferol - a precursor ofvitamin D, made in the liver, fromcholesterol

precursor migrates to the skin where it isconverted to a 2nd precursor with UV rays

next the liver and the kidneys alter the precursorinto an active form

1-25 dihydroxycholecalciferol ordehydroxy vitamin D : the final, activeform of vitamin D


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Vitamin D

two forms : considered a prohormonebecause it is converted to a hormone inthe body; each is formed from a

provitamin when exposed to UV rays D2 (ergocalciferol) - formed in plants

D3 (cholecalciferol) -formed in humans fromcholesterol in the skin

heat stable and not easily oxidized; notharmed by storage, food processing orcooking


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Functions

promotion of calcium and phosphorusabsorption in the body

thus, it helps helps increase concentration inthe blood so that normal bone and toothmineralization can occur and tetany(involuntary muscle movement; a symptom of

hypocalcemia) can be prevented absorbed in the intestine and chemically

changed in the liver and kidneys; excessamount stored in liver and adipose tissue


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Sources

sunlight as best source; sunshine vitamin

amount formed depends on pigmentation and

amount of sunlight food sources : milk, fish liver oil, egg yolk,

butter, fortified margarine

milk fortified with vitamin D


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Conversion of vitamin D

Previously in IU but later as mcg (Qg) ofcholecalciferol. To conver IU to Qg

100 IU = 2.5 Qg 400 IU = 10 Qg


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Effects ofDeficiency orExcess

rickets - malformed bones and pain ininfants

osteomalacia - softening of bones inadults

osteoporosis - brittle bones where vit D

deficiency may also contribute


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tocopherols - composed of alpha, beta,delta and gamma

tocotrienols

an anti-oxidant ; it protects othersubstances from oxidation by beingoxidized itself, esp PUFA

oxidation is a type of chemical reaction so namedbecause oxygen is one of the agents that oftenbrings it about

Vitamin E


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protects the lungs from air pollutants thatare strong oxidants

protects against heart disease byprotecting LDL from oxidation; oxidationof LDL encourages development ofatherosclerosis

Vitamin E


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Discredited claims against Vitamin E

enhances athletic skill

improves sexual performance or cures sexualdisfunction in men

prevention or cure for hereditary musculardystrophy (weakening of muscles)

delay of aging

Vitamin E


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as an antioxidant, aided by vitamin C andselenium

for the prevention of hemolytic anemia

among premature infants fall of vit E below critical levels tend to break the

RBC open to spill their content; maybe due tooxidation of PUFA; can be corrected w/ treatment

may enhance the immune system as antioxidant in foods to prevent spoiling

Functions


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Conditions that respond to vit E therapy

in non-malignant breast disease (fibrocystic breastdisease)

intermittent claudication (abnormal blood flow ofblood that causes cramping in the leg)

Toxicity high dose interfere with blood clotting action of

vitamin K enhance action of anticoagulant medications,

leading to hemorrhage

Functions


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vegetable oils made from corn, soybean,safflower,cottonseed

margarine an d products made from these

wheat germ, nuts and green leafyvegetables

Sources


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requirement increases with increase in theamount of polyunsaturated fatty acids

long term megadoses of the vitaminshould be avoided

Requirements


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detected in premature,low birthweightinfants

also in patients who are unable to absorbnormally

Deficiency


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made up of several compounds essential inblood clotting, commonly calledphylloquinone (K1), esp from green leafyvegetables

vitamin K2 or menaquinone is synthesizedin the intestine by bacteria and found alsoin animal foods

absorbed like fats mainly in the from thesmall intestine and slightly from the colon,requiring bile and improved absorption

when there is fat

Vitamin K


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essential for the formation of prothrombin,which permits proper clotting of blood

prothrombin may be given to newbornsimmediately after birth because human milk has

little vitamin K and there are little bacteria in theintestines of newborns

insufficient vitamin K makes infants prone tointracranial hemorrhage

may be given to adults after extensive antibiotictherapy

Functions


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best sources are dark green leafyvegetables such as broccoli, spinach,cabbage, kale

Dairy products

Sources

as antidote for overdose of anticoagulant

drugs (blood thinner such as WarfarinCoumadin, Warnerin) or to treat cases ofhemorrhage


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defective blood coagulation - increase inclotting time makes one prone to

hemorrhage this maybe caused by deficiency of fat

metabolism, antibiotic therapy,

inadequate diet or anticoagulants

Deficiency


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Vitamin B complex

Thiamin

Riboflavin Niacin

Vitamin B 6

Vitamin B12 Folate

Ascorbic Acid

WATER-SOLUBLEVITAMINS


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Help burn fuel but do not serve as fuelthemselves

the energy-yielding nutrients are carbohydrate,

fat and protein Many coenzymes have B vitamins as part

of their structure

Thiamin, riboflavin, niacin, pantothenic acidand biotin - part of a distinct coenzymenecessary for the production of energy fromglucose, amino acids and fats

The BVitamins


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A coenzyme containing B6 assists enzymesthat metabolize amino acids

folate and B12 - involved in duplicating genetic

material when cells divide

pantothenic acid - component of coenzyme A

The BVitamins


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a coenzyme, originally B1; partly destroyedby by heat and alkalis and lost in cooking

essential for the metabolism of

carbohydrates and some amino acids essential to nerve and muscle action

absorbed in the small intestine

best sources : unrefined and enrichedcereals, yeast, wheat germ, lean pork,organ meats and legumes

Thiamin (vitamin B1)


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requirement (mg) see RENI Deficiency : loss of appetite, fatigue,

nervous irritability, constipation; beriberi inserious deficiency

alcoholics at risk due to malabsorption;renal patients on long term dialysis andpatients on long term intravenous feeding

thiaminase - enzyme in raw fish thatinhibits normal action of thiamin;inactivated by cooking


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destroyed by light and irradiation andunstable in alkalis

essential for carbohydrate, fat and protein

metabolism essential for tissue maintenance especially

for the skin around the mouth and for

healthy eyes; absorbed in small intestine rich sources : milk, meats, poultry, fish

and enriched breads; rich sources are

broccoli, spinach, asparagus

RIBOFLAVIN (Vitamin B2)


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requirement (mg) :

deficiency : cheilosis, characterized by

fissures on the lips and cracks on cornersof the mouth; glossitis (inflammation ofthe tongue; dermatitis; eye strain in the

form of itching, burning and eye fatigue


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Niacin

generic name for nicotinic acid andniacinamide

reasonable stable in foods

serves as coenzyme in energy metabolism essential for the prevention of pellagra, a

disease characterized by sores on theskin, diarrhea, confusion, anxiety,irritability, poor memory, dizziness anduntimely death, if untreated


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niacin - when used as anti-cholesterol

lowering agent must be supervised byphysician due to side effects such as liverdamage and peptic ulcers

best sources : meats, poultry, and fish;also in peanuts and legumes

requirements (as niacin equivalent or NE =1 mg niacin or 60 mg tryptophan)

deficiency : weakness, indigestion, anxiety,irritability; pellagra (4Ds dermatitis,diarrhea, dementia,death)


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three related forms : pyridoxine, pyridoxaland pyridoxamine

essential for protein metabolism and

absorption aids in the release of glucose from

glycogen

helps in the conversion of excess aminoacids to those the body is deficient

catalyst in the conversion of tryptophan to

niacin

Vitamin B6


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helps in the formation of other substancesfrom amino acids

sources : poultry, fish, liver, potatoes,bananas, spinach

requirements (mg):

deficiency : in combination w/ other Bvitamins


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needed for DNA synthesis, proteinmetabolism and formation of hemoglobin

sources : fortified cereals, green leafyvegetables, legumes, sunflower seeds,fruits like orange juice and strawberry

destroyed by heat, UV light, oxidation,processing destroys 50-90 % folate

requirement (mcg) :

Folate ( folacin and folic acid)


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Deficiency : neural tube defect in thefetus such as spina bifida (spinal cord andspinal fluid bulge through the back),anencephaly (absence of brain);inflammation of mouth and tongue , poorgrowth, depression, mental confusion,problems with nerve function;

megaloblastic anemia (red bloodimmature and large; unable to carryoxygen properly)


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excessive intake of over the counter

supplements can mask a vit B12deficiency and inactivate phenytoin, ananticonvulsant drug used by epileptics

Sources : liver, legumes, green leafyvegetables, beets; in fruits, oranges andcantaloupe; fortified grain products

Folate interacts with alcohol - whichimpairs folate absorption and increasesexcretion


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contains cobalt slightly soluble in waterand fairly stable to heat but damaged by

strong acids or alkali; can be stored inbody for 3-5 yrs

involved in folate metabolism (assist incell division),

maintenance of the myelin sheath andhealthy red blood cells

Vitamin B12 (cobalamin)


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must bind with a glycoprotein (intrinsicfactor) present in gastric secretions ofstomach and small intestine combiningwith pancreatic protease and travel to the

ileum where it attaches to special receptorcells for complete absorption

pernicious anemia - condition of a patient

who has lost ability to produce the gastricsecretions, pancreatic protease , intrinsicfactor or special receptor cells


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best sources : animal foods, esp organmeats, lean meat, seafood, eggs and

dairy products requirements (mcg) : megaloblastic

anemia if due to insufficient B12, if due

to lack of intrinsic factor, perniciousanemia develops


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Pantothenic acid

from Greek word pantothen meaning frommany places

fairly stable but can be damaged by acids

and alkali pantothenic acid involved in metabolism of

carbohydrates, fats and protein

essential for the synthesis of theneurotransmitter acetylcholine and ofsteroid hormones


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sources : animal foods ie meats, poultry,eggs; whole grain cereals and legumes;

thought to be synthesized by the body requirements (mg)

natural deficiencies are unknown;

weakness, fatigue, burning sensation offeet


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participates as coenzyme in the synthesisof fatty acids

sources : liver, egg yolk, soy flour,cereals, yeast ; synthesized by the body

requirement (mcg)

deficiency : deficiency symptoms arenausea, anorexia,depression, pallor,dermatitis, increase serum cholesterol;toxicity unknown

Biotin


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readily destroyed by heat, air and alkali

Role of vitamin C

helps in collagen formation collagen serves as matrix on which bone is

formed, the material of scars and animportant glue that attaches cells to one

another; a protein substance that holds bodycells together making it necessary for wouldhealing; important for elasticity of capillaries



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has antioxidant properties and protectsfood from oxidation

protects water-soluble substances; by being

oxidized, vitamin C regenerates alreadyoxidized substances such as iron and copperto their original state

in the process vit C removes the damaging

oxidizing agent protects molecules incl fat soluble compounds

and vit A, E and PUFA



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Involved in the metabolism of certain aminoacids (some converted as hormones)

may be involved in the formation or

functioning of norepinephrine ( aneurotransmitter and vasoconstrictor thathelps the body cope with stressful

conditions) may reduce severity and duration of cold (as

antihistamine)



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aids in the absorption of nonheme iron

can reduce cancer risk by reducing nitrites

in foods (role in cancer being studied)


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best sources ; citrus fruits, melon,strawberries, tomatoes, potatoes

cabbage, broccoli requirement (mg) over 1 g is a megadose

deficiency : bleeding gums, loose teeth,

tendency to bruise easy, poor woundhealing, scurvy


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food no longer contains the right nutrientsin the adequate quantities

supplements can bulk up muscles andenhance athletic performance

vitamins provide needed energy

vitamins and minerals can cure anythingincluding heart trouble, the common coldand cancer

Why do people take

supplements? They believe that:


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A balanced diet does provide for thenutritional needs of healthy people

No amount of vitamins will build muscles;only weight lifting will do that

Vitamins do not provide energy

themselves. They help to release theenergy within the carbohydrates, proteinsand fats that people ingest.

The facts


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Only certain diseases caused by vitamindeficiencies( such as beriberi, scurvy,rickets) can be cured with the help of

vitamin supplements. Heart disease,cancer and the common cold cannot.

megadose - intake 10 times the RDA;

should be prescribed by physician as supplement, vitamins should not

exceed 100% of RDA

Lecture Vitamins

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