| provitamin D2 | Any substance that can give rise to ergocalciferol (vitamin D2); e.g., ergosterol. (05 Mar 2000) |
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| provitamin D3 | Cholesta-5,7-dien-3b-ol;a zoosterol in skin and other animal tissues that upon activation by ultraviolet light becomes antirachitic and is then referred to as cholecalciferol (vitamin D3). Synonym: provitamin D3. (05 Mar 2000) |
| provitamin | A chemical that becomes a vitaminvia a natural reaction within anorganism, such as when 7-dehydrocholesterol in the skin becomes vitamin Dwhen its exposed to sunlight. (09 Oct 1997) |
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| provitamin A | Trivial name for carotenoids exhibiting qualitatively the biological activity of beta-carotene, i.e., vitamin A precursors (alpha-, beta-, and gamma-carotene and cryptoxanthin); contained in fish liver oils, spinach, carrots, egg yolk, milk products, and other green leaf or yellow vegetables and fruits. (05 Mar 2000) |