A method for the assay of the antineuritic vitamin B1, in which the growth of young rats is used as a criterion

Abstract

Two methods are given. In (1) the basal diet is similar to that previously recommended for assay of the more heat stable (anti-dermatitis, ? anti-pellagra) vitamin B2 constituent of the water-soluble B vitamin complex (See B. A. 3(4-6): Entry 6032.), stress being laid upon the necessity for careful purification of the caseinogen used. Vitamin B2 is supplied by 0.4 gm. (dry weight) daily of yeast autoclaved at 120[degree] C. for 5 hrs. In (2) the caseinogen of the basal diet is replaced by fresh egg white in amount to supply 10% protein. This material is rich in vitamin B2 un- accompanied by vitamin B1. Young rats (40-50 gm. weight) placed on these diets immediately after weaning show increase in body weight for 2-4 weeks; when this is stationary or declining various doses of the materials to be tested are administered. The vitamin B1 content of the foods given is assayed by comparing the daily doses required to cause commensurate resumption of growth. Ten to twelve gm. weekly increase in body weight is a convenient standard for comparison. In tests made with equal doses of a series of yeast extracts good correspondence was found between the growth obtained on diets (1) and (2) respectively. In other tests, however, higher values were obtained on diet (1). It is suggested that a second heat-stable water-soluble dietary factor, in addition to vitamin B2, necessary for continuous growth in the rat, is present in autoclaved yeast and lacking in egg-white. Method (1) is, therefore, to be recommended above method (2) as providing a more complete basal diet.