Growth-Promoting Rachitogenic Diets for Rats

Abstract

In the Medical Research Council's 1924 “Report on the Present State of Knowledge of Food Accessory Factors ”emphasis is laid on the fact that rickets develops in well nourished children and that rachitic dogs also grow at a normal rate while the disease develops. They call attention to the lack of good growth in rats on all commonly used rachitic diets and say: “It is manifest that experimental rickets in rats as at present produced fails to fulfill the condition of being a disease occurring in well growing and apparently healthy animals. ”Some of the early diets, made up for other purposes, were highly deficient and gave little growth. Diets designed later on for rickets production were much better in this respect, but even Steenbock's diet No. 2965 falls short of normal growth. This lack of growth cannot be looked upon as a “Vitamin D ”deficiency since the addition of cod liver oil in liberal amounts will not materially improve the condition.

Several years ago we began a survey of feeding materials suitable for rickets production with a view to finding a more rational procedure for studies in experimental rickets and avoiding the obviously correct criticism of the British investigators. Numerous experiments were done with a view to satisfying the various aminoacid, vitamin and mineral requirements and it became apparent that Vitamin B (complex) was the most important factor. It was shown that by means of rice polishings a diet otherwise poor in growth and only slightly rachitogenic could be made to produce practically normal growth with a greater degree of rickets. Yeast and yeast extracts gave a marked improvement in growth but led to other complications to be discussed later.