Production of rickets and osteoporosis on diets of purified food substances.

In experiments on rickets, osteoporosis and xerophthalmia by my students and myself, white rats belonging to litters 1-150 were fed diets 1-467. In most of these white flour was an ingredient but some were made of purified food substances. It was found that a group of vitamins known as Vitamin A were all contained in the cod liver oil used; that commercially dehydrated spinach, or spinach dried in the laboratory at a low temperature, contained a growth promoting Vitamin A, and prevented xerophthalmia, but had no detectable antirachitic effect. Its effect in preventing osteoporosis was extremely small, and since the spinach contained calcium it was very difficult to decide whether the effect was due to calcium or due to vitamin. Extracts made from this spinach also failed to show antirachitic and antiosteoporotic effects. Vitamin B was derived from bakers'yeast. In most of these series of experiments, the antirachitic vitamin was kept low and constant while the calcium and phosphorus were varied. Results confirm those of Sherman and Pappenheimer as well as those of Osborne, Mendel and Park. It has not been possible so far, however, to show that rickets depended on any ratio of calcium to phosphorus, the most striking result being that low calcium produces osteoporosis and low phosphorus produces rickets.

Diagnosis of rickets was made by Dr. C. M. Jackson¹ in the earlier experiments. By comparing the diagnosis made by Dr. Jackson on gross and microscopic pathology with x-rays taken the same day, a basis of interpretation was made of x-rays, and x-rays were used for diagnosis in the later experiments. It is not possible to record all1 these experiments but the following is given as an example. Ca was added as CaSO₄ and P as KH₂ PO₄.