Vitamin A

A. Catharine Ross

Research output: Chapter in Book/Report/Conference proceedingChapter


Vitamin A (all-trans-retinol, vitamin A alcohol) is the parent molecule of a family of compounds with shared biological activities. Collectively, these compounds are essential for visual functions and for the maintenance of healthy epithelial tissues (skin, immune system organs, gastrointestinal tract, reproductive organs, lungs, and others). The nutritional term vitamin A encompasses both preformed vitamin A and provitamin A. Preformed vitamin A (retinol and its esters) occurs naturally in foods of animal origin and is added in the preparation of some fortified foods and nutritional supplements. Provitamin A compounds (b-carotene, a-carotene, and b-cyptoxanthin), which are synthesized by plants as accessory photosynthetic pigments, can be metabolized by humans and animals to retinol. The essential metabolites of vitamin A include 11-cis-retinaldehyde, the form required for vision, andalltrans-retinoic acid (RA), which functions as a hormone and an essential regulator of gene transcription.

Original languageEnglish (US)
Title of host publicationEncyclopedia of Dietary Supplements
PublisherCRC Press
Number of pages13
ISBN (Electronic)9781482204056
ISBN (Print)0824755049, 9780824755041
StatePublished - Jan 1 2004

All Science Journal Classification (ASJC) codes

  • General Pharmacology, Toxicology and Pharmaceutics
  • General Health Professions
  • General Medicine


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