ABSORPTION AND STORAGE OF VITAMIN A

The circumstances surrounding the discovery of vitamin A emphasized the indispensability of this food factor for normal nutrition. No small part of the investigative effort in the two decades since its discovery has been expended in the detection and estimation of vitamin A in food materials. Many of the puzzling features of the distribution of this factor and its behavior toward chemical manipulation have been partially explained by the recently established relationship between it and the natural pigment carotene. There is convincing evidence that the vitamin A activity of plant materials is due largely to carotene, which, when taken into the body, is transformed to vitamin A, whereas the potency of active sources of animal origin arises largely from the presence of the vitamin itself. Aside from its recognized requirement for maintenance and growth, there exists a close correlation between an adequate supply of vitamin A and the integrity of