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Vitamin A

Chemistry

Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids. Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision. Vitamin A is needed by the retina of the eye in the form of retinal, which combines with protein opsin to form rhodopsin, the light-absorbing molecule necessary for both low-light and color vision. Vitamin A also functions in a very different role as retinoic acid, which is an important hormone-like growth factor for epithelial and other cells.

Relations

  • General 

  • Medical use 

  • Side effects 

  • Dietary recommendations 

  • Sources 

  • Metabolic functions 

  • Vitamin A and derivatives in medical use 

  • History