Medicine: Vitamin X

A hitherto unknown dietary factor essential for reproduction in rats has been discovered by Dr. Herbert M. Evans and Dr. Katharine S. Bishop, of the University of California.* They call it “;Vitamin X.” “Vitamins,” now so popular, were unknown ten years ago. They have not been isolated. They cannot be seen or weighed. They came to light only when it was found that diets apparently perfectly balanced according to pre-existent information did not provide proper nourishment in some cases arid even brought on certain “; deficiency “; diseases (e. g., scurvy, beriberi, pellagra). There are three major vitamins (Fat-soluble A, Water-soluble B, Water-soluble C), and all three must be present in any correct diet. Plenty of milk and oranges or tomatoes will furnish all of them. But they are not units of measurement and have in no way abolished the necessity for a balance of other elements in the food, nor for an adequate total of energy units.

When female rats were raised (by Doctors Evans and Bishop) on a standard synthetic diet used in animal laboratories, containing vitamins A and B, they became fat, sleek and healthy, but practically all of them were sterile. When fresh green lettuce leaves were added to their menu, the sterile rats produced litters. Drs. Evans and Bishop found this X-substance also in the whole-wheat grain, egg yolk, beef liver and some other foods, but not in milk, the otherwise perfect food. The absence of Vitamin X affects the reproductive powers of the male, as well as the female rat. This vitamin can be extracted from the wheat embryo with ethyl alcohol and ether and a daily dose of 100 milligrams of the resulting oil cures sterility in the rats.

Whether the data on Vitamin X can be applied to other animals, including humans, has not yet been determined. But it can be said, at least, that much of our present-day knowledge of human nutrition and physiology was first learned through experiments on rats.

* JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, Vol. 81, No. 11, Sept. 15, 1923.