[Skip to Content]
[Skip to Content Landing]
Other Articles
September 2, 1950

DEFICIENCIES OF THE FAT-SOLUBLE VITAMINS

JAMA. 1950;144(1):34-45. doi:10.1001/jama.1950.62920010016008
Abstract

VITAMIN A  In addition to the general limiting effect on growth common to all nutrients, vitamin A seems to affect almost exclusively the mechanism of the adaptation of vision to dim light (dark adaptation) and the health and integrity of the epithelium. The functional and structural changes resulting from a deficiency of this vitamin constitute the manifestations of the deficiency disease.

Dark Adaptation.—  The adaptation of vision to dim light, principally a function of the retinal rods, requires an adequate supply of vitamin A (vitamin A1). The process depends on the presence of an adequate amount of visual purple (rhodopsin). Vitamin A with a protein forms visual purple. Visual purple, or rhodopsin, is reversibly broken down in bright light to retinene, which in turn is reconverted to vitamin A1 by a reaction involving reduced cozymase as a co-enzyme. Recent studies indicate a complicated process possibly involving two

First Page Preview View Large
First page PDF preview
First page PDF preview
×