Retinol, the dietary form of vitamin A, is a fat-soluble, antioxidant vitamin
important in vision and bone growth. It belongs to the family of chemical compounds
known as retinoids. Retinol is ingested in a precursor form; animal sources (milk
and eggs) contain retinyl esters, whereas plants (carrots, spinach) contain
carotenoids. Tissue cells convert these precursors to retinol, and then to either
retinal or retinoic acid. Many of the non-vision functions of vitamin A are mediated
by retinoic acid, which acts at intracellular retinoic acid receptors. Retinoic acid
is used medicinally as a topical treatment for acne. The other main metabolite,
retinal, is used in vision.
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