Vitamin A: Physiology, Dietary Sources, and Requirements

Research output: Chapter in Book/Report/Conference proceedingChapter


Vitamin A (retinol) physiology comprises of reactions that take place in the intestine (absorption), liver (uptake, storage, metabolism, secretion, and elimination), and target organs including nearly all the tissues of the body, especially the eye, immune system, reproductive organs, and other epithelial tissues. These reactions result in the conversion of dietary forms of vitamin A, either retinyl esters or β-carotene, into functionally active metabolites, 11-cis-retinal in the retina, and all-trans-retinoic acid in nearly all tissues. Various binding proteins, enzymes, and nuclear receptors participate in the metabolism and functions of vitamin A in vision and the regulation of gene expression.

Original languageEnglish (US)
Title of host publicationEncyclopedia of Human Nutrition
PublisherElsevier Inc.
Number of pages7
ISBN (Electronic)9780123848857
ISBN (Print)9780123750839
Publication statusPublished - Jan 1 2012


All Science Journal Classification (ASJC) codes

  • Medicine(all)

Cite this

Ross, A. C. (2012). Vitamin A: Physiology, Dietary Sources, and Requirements. In Encyclopedia of Human Nutrition (Vol. 4-4, pp. 333-339). Elsevier Inc..