- Vitamin A: Nutritional Aspects of Retinoids and Carotenoids
Vitamin A is now a century old, having rst been identied in 1913 as an essential component of the diet in rodent studies by E.V. McCollum and Margurite Davis at the University of Wisconsin, and independently by Osborne and Mendel at Yale. Both groups were studying the effects of diets made from puried protein and carbohydrate sources such as casein and rice our on the growth of young rats. They observed growth cessation and mortality in rats fed the puried diets, unless the diet was supplemented with butter, sh oils, or a quantitatively minor ethersoluble fraction extracted from these substances or milk or meats. “Fat soluble A” was soon recognized to also be extractable from yellow vegetables, and this substance was later identi-ed as carotene. Early studies on vitamin A deciency linked this nutritional state to specic disease conditions, including xerophthalmia, squamous metaplasia of epithelial and mucosal tissues, increased susceptibility to infections, and abnormalities of reproduction. Vitamin A was chemically identied, and retinol and β-carotene (β-C) were rst synthesized, in the 1930s. In 1937, Paul Karrer, a Swiss chemist, shared the Nobel Prize in Chemistry for his investigations on carotenoids, vitamin A, and other natural compounds. Detailed reviews on the history of vitamin A can be found in Refs.  and .