VITAMINS

Organic compounds that are essential for normal body growth and maintenance. They are classified into two groups: fat-soluble ( A, D, E, and K) vitamins, and water-soluble vitamins ( B and C). Vitamins are measured in very low concentrations, such as 1–100 mg. Through biochemical action, they perform various functions in such processes as cell growth, normal digestion, manufacture of red blood cells, and absorption of calcium and phosphorus. Inadequate vitamin intake can be the result of food deficiency, increased vitamin requirements, and increased vitamin loss. The vitamins of determined importance include: A (retinol), B1 (thiamine), B2 (riboflavin), B5 (pantothenic acid), B6 (pyridoxine), B12 (cyanocobalamin), C (ascorbic acid), D2 (calciferol), E (tocopherol), K, niacin, folic acid, and biotin.

Vitamins are a class of organic substances required in small amounts by living organisms to maintain normal health.
Some well-identified vitamins are (a) vitamin A (retinol), (b) vitamin B complex which are water-soluble vitamins [for example, vitamin B1 (thiamin), B2 (riboflavin), B6 (pyridoxine) and B12 (cyanocobalamin)], (c) vitamin C (ascorbic acid), (d) vitamin D, (found in the liver and in fish oils), which is important for the absorption of calcium and for the prevention of diseases like rickets in children and osteomalacia in adults, (e) vitamin E (tocopherol), (f) vitamin H (biotin), (g) vitamin K, found mainly in green leaves, and essential in treating blood-clotting, (h) vitamin M (folic acid), and (i) vitamin P. Bioflavanoides are regarded as a vitamin in the USA. Most B and C vitamins occur in plants, animals and micro-organisms. The vitamin D group includes vitamin D2 (calciferol) and D3 (cholecalciferol). The vitamin K group includes K1, (phylloquinone) and K2 (menaquinone).
Animals cannot synthesize many vitamins and these must, therefore, be supplied in their food through plants and microbes. Vitamin A, D, E and K are fat-soluble and are stored in fat bodies. Vitamins B and C are watersoluble and cannot be stored, and have to be regularly supplied through the diet.
All animals contain gut bacteria capable of producing sufficient amount of B vitamins. The livestock are able to produce adequate supplies of vitamin D in their coats and skin, irradiated during the summer months.
Foods may contain vitamin precursors (called provitamins) , and they change chemically in the body to form actual vitamins. Many vitamins are destroyed by light and heat, (e. g , , during cooking). When brown rice is milled, it is deprived of about 80% of thiamin, 56% of riboflavin, 65% of niacin, 60% of pantothenic acid and 55 % pyridoxine.
Many people depend on rice for a major part of energy intake (almost 80 %). But highly polished rice is deficient in B complex, which is subsequently made up by the addition of thiamin, niacin and iron.
Vitamins and minerals reduce the incidence of diseases like beriberi, pellagra, scurvy, etc. Milled rice can be enriched by coating it with enriching ingredients. Par boiling can be considered as a form of enrichment as some vitamins and minerals are retained in the process.
Deficiencies of some vitamins can cause ill health. To overcome these deficiencies in animals, livestock feed must contain synthetic vitamin supplements, added in balanced amounts according to the needs of the animals.
Vitamins function as coenzymes. Active parts of the enzyme systems catalyze many anabolic and catabolic reactions of living organisms, necessary for producing energy, synthesizing tissue components, hormones and chemical regulators, and detoxification and degradation of waste products. Owing to their role in metabolism, vitamins are generally concentrated in metabolically most active tissues of animals and plants; for example, in the liver or kidneys, and in seed germ.