Provitamin
Substances animals can metabolize into vitamins
From Wikipedia, the free encyclopedia
A provitamin is a substance that may be converted within the body to a vitamin.[1] The term previtamin is occasionally used as a synonym,[2][3] though it has its own distinct usage for Vitamin D.
The term "provitamin" is used when it is desirable to label a substance with little or no vitamin activity, but which can be converted to an active form by normal metabolic processes.[citation needed]
Example
Some provitamins are:
- "Provitamin A" is a name for β-carotene,[1] which has only about 1/6 the biological activity of retinol (vitamin A); the body uses an enzyme to convert β-carotene to retinol. In other contexts, both β-carotene and retinol are simply considered to be different forms (vitamers) of vitamin A.
- "Provitamin B5" is a name for panthenol, which may be converted in the body to vitamin B5 (pantothenic acid).
- Menadione is a synthetic provitamin of vitamin K.
- Provitamin D2 is ergosterol, and provitamin D3 is 7-dehydrocholesterol. They are converted by UV light to previtamin D2 and previtamin D3, which in turn spontaneously convert to vitamin D2 and vitamin D3.[4][5]
The human body produces provitamin D3 naturally; deficiency is usually caused by a lack of sun exposure, not a lack of the provitamin.[6]
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