a fat-soluble, crystalline, unsaturated alcohol, C 28 H 43 OH, occurring in milk, fish-liver oils, etc., produced by ultraviolet irradiation of ergosterol, and used as a dietary supplement, as in fortified milk. Also called vitamin D2.
a fat-soluble steroid, found esp in fish-liver oils, produced by the action of ultraviolet radiation on ergosterol. It increases the absorption of calcium from the intestine and is used in the treatment of rickets. Formula: C28H43OH Also vitamin D2