FAT-SOLUBLE VITAMINS A, E AND K
- HUGH R. BUTT, M.D.
Since this article does not have an abstract, we have provided the first 150 words of the full text.
Excerpt
Chemistry.— Vitamin A is a colorless, fat-soluble vitamin. Karrer and associates isolated it in 1931 and determined its structure, but effective syntheses of vitamin A were achieved by Milas1 and others only during the last five years.
The vitamin is an alcohol and hence is not itself saponifiable. Evidence has been presented indicating that vitamin A occurs in more than one form. The form that predominates in the tissues of salt water fish and mammals has been designated as vitamin A1 and the form which predominates in the tissues of fresh water fishes as vitamin A2. Both forms appear to exert similar functions, although vitamin A1 is considerably more effective in mammals than vitamin A2. The international unit of vitamin A has been fixed as the activity of 0.6 micrograms of pure beta-carotene. This, dissolved in a vegetable oil at such concentration
