Chemistry:Provitamin
From HandWiki
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.
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 ({{{2}}}) 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]
References
- ↑ 1.0 1.1 "provitamin". https://medical-dictionary.thefreedictionary.com/provitamin.
- ↑ Oxford Dictionary of Biochemistry and Molecular Biology. Oxford University Press. 1 January 2006. doi:10.1093/acref/9780198529170.001.0001. ISBN 978-0-19-852917-0. https://www.oxfordreference.com/display/10.1093/acref/9780198529170.001.0001/acref-9780198529170-e-16265.
- ↑ "previtamin - definition of previtamin in the Medical dictionary". The Free Dictionary. https://medical-dictionary.thefreedictionary.com/previtamin.
- ↑ Carey, Francis A.; Sundberg, Richard J. (1990). Advanced Organic Chemistry. Part A: Structure and Mechanisms (3rd ed.). New York: Plenum Press. p. 616. ISBN 0-306-43440-7. https://archive.org/details/advancedorganicc00care.
- ↑ Björn, Lars Olof (6 December 2012). Photobiology: The Science of Light and Life. Springer Science & Business Media. pp. 265–266. ISBN 978-94-010-0581-4. https://www.google.com/books/edition/Photobiology/n0TvCAAAQBAJ?gbpv=1&pg=PA266. Retrieved 27 February 2026. "Ultraviolet-B radiation can photoisomerize the provitamins to the corresponding previtamins ... The previtamins are slowly converted by a non-enzymatic and non-photochemical reaction to the vitamins."
- ↑ "Office of Dietary Supplements - Vitamin D" (in en). https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/.
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