The Composite Nature of Vitamin B.

Abstract

Chick and Roscoe 1 have recently reviewed and amplified the evidence that vitamin B involves two factors of importance for young rats, one thermolabile, the other stable under several hours autoclaving at 125°. Seidell 2 has shown that the stable factor does not noticeably contribute to the well-being of pigeons on a polished rice diet. In this paper we present evidence confirming these findings and throwing some further light on the multiple nature of vitamin B.

We used as supplements (1) aqueous extract of brewers yeast, (2) fullers earth activated with the same extract with interposition of a collodion membrane, as described in a forthcoming paper in the Journal of Biological Chemistry, and (3) brewers yeast which had been autoclaved for 6 hours at 125°. As a basal diet we used a typical synthetic preparation, the No. 107 diet of Sherman and Spohn. 3 In all cases the diets were fed ad libitum, and the supplements separately, so as to insure their complete consumption. Identical lots of material were used throughout the experiments tabulated.

We have been led to conclude: (1) That the dietary requirements of adult pigeons are distinctly different from those of young rats, since identical diets gave contrasting results, cf., Exp. 5 and 6. (2) That young rats require two B factors, one of which is of little or no consequence to pigeons. (3) That, on the other hand, pigeons require something not required by young rats, since normal weight of pigeons was not maintained on a diet that supported normal growth in rats. See Exp. 6. This third unknown factor required by pigeons but not by rats is present in whole wheat, for birds assume a higher and normal level of weight when fed whole wheat.