Article
Article
Vitamin D
Article By:
DeLuca, Hector F. Department of Biochemistry, University of Wisconsin, Madison, Wisconsin.
Last reviewed:August 2020
DOI:https://doi.org/10.1036/1097-8542.734400
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- Vitamin D, published June 2014:Download PDF
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The collective term for a group of fat-soluble sterol-like compounds, particularly vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D, also known as calciferol, is essential for the proper formation of the skeleton and for mineral homeostasis. In humans, the two most important forms are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) [see illustration]. Vitamin D2 is formed from the irradiation of ergosterol, which is a plant sterol. In contrast, vitamin D3 is normally manufactured in the skin, where ultraviolet light (for example, sunlight) activates the compound 7-dehydrocholesterol. Vitamins D2 and D3 are about equal in activity in most mammals (excluding New World monkeys) and birds; in general, vitamin D2 is approximately one-tenth as active as vitamin D3. See also: Nutrition; Vitamin
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