Fat-soluble vitamins

vitamin /vi·ta·min/ (vi´tah-min) any of a group of unrelated organic substances occurring in many foods in small amounts and necessary in trace amounts for the normal metabolic functioning of the body; they may be water- or fat-soluble.

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vitamin A  retinol or any of several fat-soluble compounds with similar biological activity; the vitamin acts in numerous capacities, particularly in the functioning of the retina, the growth and differentiation of epithelial tissue, the growth of bone, reproduction, and the immune response. Deficiency causes skin disorders, increased susceptibility to infection, nyctalopia, xerophthalmia and other eye disorders, anorexia, and sterility. As vitamin A it is mostly found in liver, egg yolks, and the fat component of dairy products; its other major dietary source is the provitamin A carotenoids of plants. It is toxic when taken in excess; see hypervitaminosis A.

vitamin A1  retinol.

vitamin A2  dehydroretinol.

vitamin B1  thiamine.

vitamin B2  riboflavin.

vitamin B6  any of a group of water-soluble substances (including pyridoxine, pyridoxal, and pyridoxamine) found in most foods, especially meats, liver, vegetables, whole grains, cereals, and egg yolk, and concerned in the metabolism of amino acids, in the degradation of tryptophan, and in the metabolism of glycogen.

vitamin B12  cyanocobalamin by chemical definition, but generally any substituted cobalamin derivative with similar biological activity; it is a water-soluble hematopoietic vitamin occurring in meats and animal products. It is necessary for the growth and replication of all body cells and the functioning of the nervous system, and deficiency causes pernicious anemia and other forms of megaloblastic anemia, and neurologic lesions.

vitamin B complex  a group of water-soluble substances including thiamine, riboflavin, niacin (nicotinic acid), niacinamide (nicotinamide), the vitamin B6 group, biotin, pantothenic acid, and folic acid, and sometimes including p- aminobenzoic acid, inositol, vitamin B12, and choline.

vitamin C  ascorbic acid.

vitamin D  either of two fat-soluble compounds with antirachitic activity or both collectively: cholecalciferol, which is synthesized in the skin and is considered a hormone, and ergocalciferol, which is the form generally used as a dietary supplement. Dietary sources include some fish liver oils, egg yolks, and fortified dairy products. Deficiency can result in rickets in children and osteomalacia in adults, while excessive ingestion can cause hypercalcemia, mobilization of calcium from bone, and renal dysfunction.

vitamin D2  ergocalciferol.

vitamin D3  cholecalciferol.

vitamin E  any of a group of at least eight related fat-soluble compounds with similar biological antioxidant activity, particularly α-tocopherol but also including other isomers of tocopherol and the related compound tocotrienol. It is found in wheat germ oil, cereal germs, liver, egg yolk, green plants, milk fat, and vegetable oils and is also prepared synthetically. In various species it is important for normal reproduction, muscle development, and resistance of erythrocytes to hemolysis.

fat-soluble vitamins  those (vitamins A, D, E, and K) that are soluble in fat solvents and are absorbed along with dietary fats; they are not normally excreted in the urine and tend to be stored in the body in moderate amounts.

vitamin K  any of a group of structurally similar fat-soluble compounds that promote blood clotting. Two forms, phytonadione and menaquinone, exist naturally, and there is one synthetic provitamin form, menadione. The best sources are leafy green vegetables, butter, cheese, and egg yolk. Deficiency, usually seen only in neonates, in disorders of absorption, or during antibiotic therapy, is characterized by hemorrhage.

vitamin K1  phytonadione.

vitamin K2  menaquinone.

vitamin K3  menadione.

water-soluble vitamins  the vitamins soluble in water (i.e., all but vitamins A, D, E, and K); they are excreted in the urine and are not stored in the body in appreciable quantities.

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Fat-soluble vitamins

Fat-soluble vitamins can be dissolved in oil or in melted fat.

Mentioned in: Vitamin B 6 Deficiency