Vitamins are essential organic micronutrients required by body in small quantities to support metabolism, immunity and growth. They are not manufactured in body in sufficient amounts, therefore, they have to be supplemented through diet.
Vitamins can be classified into two major categories : fat soluble and water soluble vitamins.
Fat soluble vitamins – vitamin A, D, E and K. These dissolve in fat. These are stored in fatty tissue and liver.
Water soluble vitamins – vitamin B complex (B1, B2, B3, B5, B6, B7, B9, B12) and vitamin C. These dissolve in water and are not stored by the body.

IMPORTANT VITAMINS
| VITAMINS | DAILY REQUIREMENT | SOURCES | FUNCTION | DEFICIENCY SYMPTOMS | PREVENTION AND CONTROL OF DEFICIENCY |
| 1) Vitamin A (Retinol) | Infants – 300-400 microgram Adults – 750 microgram Children – 400-600 microgram Pregnancy and lactation – 750+400 microgram (one international unit of vitamin A = 0.3 microgram of Retinol) | Yellow vegetables and fruits (carrots, papaya, pumpkin, mangoes, liver, egg yolk, milk and its products, fish, fish liver oil) | i) Essential for normal vision ii) Maintains epithelial cells of skin and mucous membrane iii) Regulates body growth, especially skeletal growth iv) Protects body against infections | i) Decreased resistance to infections ii) Dry scaly skin (toad skin) iii) Night blindness iv) Xerophthalmia : a severe, progressive ocular disease, characterized by abnormal dryness of conjunctiva and cornea. Its stages are – conjunctival xerosis ( dry, wrinkled conjunctiva), Bitot’s spots (rough, greyish raised patches on conjunctiva), corneal xerosis (dry, hazy cornea), keratomalacia ( softening of cornea) | i) Regular intake of diet rich in vitamin A ii) Oral administration of 200,000 I.U of vitamin A drops every 6 months to pre-school children. |
| 2) Vitamin D (Cholecalciferol) | Infants and children – 10 microgram Adults – 7.5 microgram Lactation – 15 microgram ( 1 microgram of cholecalciferol = 40 I,U. of vitamin D) | Fish, liver, fish liver oils, eggs, butter, milk and its products, generated in the skin by the action of ultra-violet rays of sunlight. | i) Increases intestinal absorption of calcium and phosphate. ii) Mineralization of bones and teeth. | Rickets in children and Osteomalacia in adults. | i) Adequate sun exposure ii) Vitamin D supplement |
| 3) Vitamin E | Adults – 10 mg ( 15 I.U.) | Milk, eggs, oils, meat, leafy vegetables | i) Antioxidant activity ii) Co-factor in electron transport chain | Sterility, muscle wasting, ataxia, foetal death, testicular degeneration, hemolysis of red blood cells in animals. | No deficiency symptoms as it is widely distributed in food. |
| 4) Vitamin K | Adults – 30 microgram | Green leafy vegetables, cereals, fruits, synthesized by bacteria in GIT. | Activates clotting factors (especially prothrombin) by catalyzing gamma carboxylation of glutamic acid. | Prolongation of clotting time, leading to bleeding disorders. | Administration of single oral dose of vitamin K to premature infants. |
| 5) Vitamin B1 (Thiamine) | Children – 0.5 – 1 mg Adults – 1 – 1.5 mg Pregnancy and lactation – 1.5 – 2 mg | Meat, fish, liver, eggs, milk, cereals, pulses, fruits, vegetables, grains, nuts, yeast | Carbohydrate utilization, maintenance of good appetite, helps in digestion | Beri-beri. Wet beriberi – affects cardio-vascular system. Causes fluid retention, increased heart rate, swollen legs, breathlessness, heart failure. Dry beriberi – affects nervous system. It leads to peripheral neuropathy. | i) Consumption of thiamine rich food. ii) Use of parboiled or undermilled rice. |
| 6) Vitamin B2 ( Riboflavin) | 2 mg | Milk, meat, liver, green leafy vegetables, pulses, germinating cereals, synthesized by bacteria in large intestine. | i) Constituent of flavo-protein which helps in tissue oxidarion and respiration. ii) Helps in protein, fat and carbohydrate metabolism. | Glossitis, cheilosis, soreness of tongue, dermatitis, redness and burning sensation in eyes. | Adequate intake of foods rich in riboflavin.. |
| 7) Vitamin B3 (Niacin) | 10 – 15 mg | Yeast, meat, kidney, liver, cereals, pulses, germinating seeds, green vegetables, synthesized in body in liver. | Helps in normal functioning of skin, intestinal tract and nervous system. | Pellagra – characterized by 3 D’s : dermatitis, diarrhoea, dementia (memory loss) glossitis, mental disorders, polyneuropathy | Adequate intake of niacin rich foods. |
| 8) Vitamin B5 (Pantothenic acid) | 10 mg | Eggs, liver, yeast, vegetables | Constituent of coenzyme A | Dermatitis, enteritis, alopecia, (hair loss), adrenal insufficiency. | Widely distributed in food, so deficiency symptoms rarely seen. |
| 9) Vitamin B6 (Pyridoxine) | 1.5 mg | Yeast, wheat, corn, liver, cereals, legumes. | Help in metabolism of amino acids, fats and carbohydrates. | Convulsions, hyperirritability, dizziness, vomiting. | Vitamin B6 supplementation. |
| 10) Vitamin B7 (Biotin) | In traces | Egg yolk, liver, tomatoes. | Catalyzes carbon dioxide fixation in fatty acid synthesis. | Dermatitis, enteritis. | Deficiency symptoms rarely occur as it is widely distributed in food. |
| 11) Vitamin B9 (Folic acid) | Children and adults – 100 microgram Pregnancy – 300 microgram Lactation – 150 microgram | Liver, eggs, green leafy vegetables. | i) Coenzyme for 1 carbon transfer. ii) Involved in methylation reaction during DNA synthesis. | Sprue (malabsorption), megaloblastic anemia, sterility, low birth weight babies. | i) Avoid overcooking of food as it destroys folates. ii) Folic acid supplementation in pregnancy and in growing children since they need more folic acid. |
| 12) Vitamin B12 (Cyanocobalamin) | Children – 0.2 – 1 microgram Adults, pregnancy and lactation – 1 microgram. | Liver, meat, eggs, milk, synthesized by bacteria in colon. | i) Coenzyme in amino-acid metabolism. ii) Stimulates production of RBCs from bone marrow. iii) Required for DNA synthesis. | Pernicious anemia, infertility, neurological and mental disturbances. | Prophylactic administration in pure vegetarians as it is not found in vegetarian food. |
| 13) Vitamin C (Ascorbic acid) | Infants – 20 mg Children – 40 mg Adults – 40 mg Pregnancy and lactation – 80 mg | Citrus fruits (amla, lemon, orange, tomato), green leafy vegetables, | i) Necessary for collagen synthesis. ii) Helps in wound healing. iii) Prevents bleeding from small blood vessels. | Scurvy – characterized by : Swollen, spongy and bleeding gums, easy bruising and skin hemorrhages, anemia. | i) Increase dietary intake of vitamin C. ii) Vitamin C supplementation to milk fed children. |
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