vitamin D n.
A fat-soluble vitamin occurring in several forms, especially vitamin D2 or vitamin D3, required for normal growth of teeth and bones, and produced in general by ultraviolet irradiation of sterols found in milk, fish, and eggs.
vitamin D2 n.
A white crystalline compound produced by ultraviolet irradiation of ergosterol. Also called calciferol, ergocalciferol.
vitamin D3 n.
A colorless crystalline compound found in fish-liver oils, irradiated milk, and all irradiated animal foodstuffs and having biological activity similar to vitamin D2. Also called cholecalciferol.
|vitamin D |
Any of a group of fat-soluble sterols necessary for normal bone growth, especially vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D is found in milk, fish, and eggs and can be produced in the skin on exposure to sunlight. A deficiency of vitamin D in the diet causes rickets in children.
|vitamin D2 |
A white crystalline sterol produced by ultraviolet irradiation of ergosterol and also occurring naturally in fungi and some fish oils. Vitamin D2 is the form of vitamin D generally used as a dietary supplement. Also called calciferol, ergocalciferol. Chemical formula: C28H44O.
|vitamin D3 |
A colorless, crystalline steroid hormone that the body synthesizes in the skin when its precursor, a derivative of cholesterol, is irradiated by sunlight. Vitamin D3 is also found in fish-liver oils, irradiated milk, and all irradiated animal foodstuffs. Also called calciferol, cholecalciferol. Chemical formula: C27H44O.