Further Evidence of Additional Substances Essential to Mammalian Nutrition

Abstract

This paper briefly reports some of the experimental evidence encountered in the course of experiments on vitamin G, which can best be interpreted by postulating the existence of more than the 6 vitamins generally recognized as factors in mammalian nutrition. The evidence included is of two types. The first type deals with the supplementary nature of 2 sets of vitamin G-containing products, and the second with the contrasting growth response of animals of different nutritional history, during the latter part of a vitamin G-test period.

In testing by the Bourquin and Sherman method 1 the vitamin G potency of laboratory preparations obtained in fractionation and concentration experiments, a supplementary effect on growth was observed when a mixture of 2 fractions of skim milk powder was fed, as contrasted with the results obtained upon feeding twice the quantity of either fraction by itself. Fig. 1 shows the effect upon gain curves of feeding daily, (a) a definite quantity (2x) of an extract made at room temperature from skim milk powder with 80% (by weight) alcohol; (b) a definite quantity (2y) of the residue left after extracting the milk powder as described in (a), and (c) a mixture (x + y) of half of each quantity of the products just described. During the first few weeks of the test period, the rate of gain permitted by the mixture of the 2 supplementary materials was between that permitted by either given separately, as would be expected if vitamin G were the sole growth-limiting factor. But during the latter part of the test period, the rate of growth permitted by the mixture exceeded that allowed by either of the supplements alone. These results can be explained by postulating that the bodily requirement of some nutritive essential other than vitamin G (in the strict sense of the Bourquin method) was not furnished by the basal diet, and was unequally supplied by the 2 fractions of the milk powder, the residue containing relatively more of the “new” factor.