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VITAMINS
Vijayalakshmi
INTRODUCTION
organic molecules with wide variety of capacitiesprominent function - cofactors for enzymatic reactions generally cannot be synthesized by mammalian cells Vitamins are usually supplied in the diet or in dietary supplements necessary for our growth, energy, and general well-being
HISTORY
Ancient Egyptians recognized night blindness 1747-Scottish naval surgeon James Lind discovered the unknown nutrient (vitamin C) in citrus foods prevented scurvy
1753- Lind published his Treatise on the Scurvy 1860- Louis Pasteur demonstrated that microscopic organisms can cause diseases1880- Christian Eijkman
vitamin-deficiency conditions in animals on an experimental basis 1905- Julius Friedenwald and John Ruhräh
Beri-Beri is probably of microbic origin
1906- Frederick Hopkin's - foods contain a small amount of “growth factors” 1911- Casimir Funk discovered what he
termed "vitamines" 1919- “Eat and Be Healthy”, Virgil MacMickle, M.D., of Portland
“ chemical substances of which the body is composed are similar to those of the foods which nourish it. They are made up of the same chemical elements...the body can only get these from foods...”
FUNCTIONS
Digestion
Converting food into energy
Cell division and growth
Tissue repair
Transporting oxygen and wastes in the circulation
Immunity
FUNCTIONS
Mental alertness
Making hormones
Reproduction
Protecting the body from poisons
Neutralizing the harmful by-products of metabolism such as free radicals
CLASSIFICATIONWater soluble Fat soluble
Thiamin (B1)
Riboflavin (B2)
Niacin (B3)
Pantothenic acid (B5)
Pyridoxine (B6)
Biotin, Folic acid
Cobalamin (B12)
Ascorbic acid
Vitamin A
Vitamin D
Vitamin E
Vitamin K
VITAMIN AVitamin A consists of three biologically active molecules, retinol, retinal and retinoic acidRetinol - “sticky” and light sensitive Provitamin A carotenoids – converted to retinol by the body ex- Beta (b)-carotene
Sources
milk, cheese, cream, liver, kidney, cod and halibut fish oil milk, Beta carotene - carrots, pumpkin, sweet potatoes, winter squashes, cantaloupe, pink grapefruit, apricots, broccoli, spinach and most dark green leafy vegetables
FUNCTIONS-VISION
isom eriza tion o f 1 1 -c is re tin a l toa ll-tran s re tin a l
1 1 -c is re tin a l g oes to rod ce llsan d b in d s w ith p ro te in
ca lled op s in to fo rmvisu a l p ig m en t ca lled rh od op s in
1 1 -c is re tin a l
1 1 -c is re tin o l
re tin yl e th e r
R E TIN O L
Immunity- maintains integrity of skin and mucosal cells - Development and differentiation of WBC- by
Retionic Acid- activation of t-cells requires all-trans RA binding
Growth and Development-embryonic development• Regulation of expression of gene for growth hormone
Red blood cell production DEFICIENCIES:
Night Blindness- Bitot’s spot, Xeropthalmia
infectious disease – Diarrhea, respiratory diseases
VITAMIN D
synthesized only when exposed to sunshine.Converted to active form, a,25-dihydroxyvitamin DThe a,25-dihydroxyvitamin D acts as a hormone, and has a specific nuclear receptor
SOURCES
Sunlight(PRIMARY)MILK PRODUCTS:Cheese, butter, margarine, cream, fortified milk SEA FOODS :fish, oystersfortified cereals.
FUNCTIONS:Calcium metabolism Vitamin D endocrine system - D3 bounds to vitamin D-binding protein and transported to liver- converted to 25-OH-D3 or calcidol (inactive)- increase exposure of sunlight – increase blood level of calcidol- hydroxyled to 1,25-OH-D3 or calcitriol- parathyroid hormone released
Vitamin D receptor – Vitamin D Receptor to Retinoic Acid X Receptor to form heterodimer-interacts with DNA
Vitamin D Responsive Elements - change in transcription of a nearby gene.
Cell differentiation- proliferation- psoriasis - the proliferation of skin cells called keratinocytes
- identification of VDR in keratinocytes led to the use of creams containing analogs of calcitriol in the treatment of severe cases of psoriasis.
Immunity – WBC recognizes Antigens- Autoimmune disease - Immune responses are mediated by T-Cells
DEFICIENCIES:RicketsOsteomalacia
VITAMIN K
The K vitamins exist naturally as K1 (phylloquinone) in green vegetables
K2 (menaquinone) produced by intestinal bacteria
K3 is synthetic menadione.
SOURCE
Spinach, cauliflower and other green leafy vegetables
chief source of vitamin K is synthesis by bacteria in the large intestine
FUNCTIONSCoagulation (clotting)
- ability to bind Ca2+ required for activation of the 7 “vitamin k-dependent” clotting factor in the coagulation cascade
- Factors II , VII, IX,X make up the core- Protein Z enhances the action of thrombin by promoting
association with phospholipids- Protein C and S control cascade- Vitamin k-dependent factors synthesized in liver
Bone mineralization – Osteocalcin – Osteoblasts- regulated by active form of vitamin D or calcitriol.
DEFICIENCIES
Liver disease
Poisoning with vitamin K antagonists
Hemorrhagic disease of the newborn results from vitamin K deficiency in human infants
Increased risk of fractures or reduced bone density may result from inadequate intake of vitamin K
VITAMIN E
Describes a family of 8 alpha, beta, gamma, delta and 4 tocotrienolsAlpha tocopherol is the only vitamin E that is actively maintained in human body found in tissues and bloodMaintains integrity of cell membrane and protects fats from oxidation
VITAMIN E
SOURCES:
Vegetable oils, nuts, egg yolk, Parmesan, chickpeas, wheat germ, oatmeal, olives,carrots, parsnips, red peppers, green leafy vegetables, sweet potatoes, tomatoes, sweet corn
DEFICIENCIES:Sever malnutrition
Genetic defects
Fat malabsorption
Neurological symptoms
VITAMIN B
THIAMIN B1
RIBOFLAVIN B2
NIACIN B3
PANTOTHENIC ACID B5
VITAMIN B6
TYPE FUNCTION
SOURCE
DEFICIENCY
B1
Thiamin pyrophosphate
Coenzyme
non – coenzyme function
Whole grains,
cereals, legumes nuts, lean pork, yeast
BERI-BERI
B2
Flavin mononucleotide
Flavin adenine dinucleotide
Oxidation-reduction (redox) reactions
Antioxidant functions
liver, eggs, cheese, milk and cereals
damage to eyes, mouth, and genitals
NIACIN
found in fish,poultry, meat, nuts and eggs
Niacin is required for the synthesis of of the active form of vitamin B3 NICOTINAMIDE ADENINE DINUCLEOTIDE
Deficiency disease is pellagra
VITAMIN B6
PYIDOXAL, PYRIDOXAMINE and PYRIDOXINE
Protein metabolism
Deficiencies are rare and usually related to overall deficiency of all the B-complex vitamins.
VITAMIN C
derived from glucose via the uronic acid pathway
extracted from plant sources such as rose hips, blackcurrants or citrus fruits
easily oxidised in air
SOURCES
Broccoli, Brussels sprouts, cauliflower, cabbage, mange tout, green leafy vegetables, red peppers, chilies, watercress, parsley, blackcurrants, strawberries, kiwi fruit, guavas, citrus fruit.
VITAMIN C
FUNCTIONS:synthesis of collagen, neurotransmitter, norepinephrine
protects indispensable molecules
regenerate other antioxidants such as vitamin E
DEFICIENCY:Scurvy