A NOTE ON THE TECHNIQUE FOR STUDYING VITAMIN B

Abstract

Although for more than a decade the vitamins have been recognized as dietary essentials and although numerous experimental data on the distribution of these food factors have been gathered, the satisfactory methods available for their detection and relative quantitative determination are singularly few.Various techniques, such as the yeast growth tests, have been devised in an attempt to obviate the use of animals, but they have not proven satisfactory.Today the most desirable and accurate means of testing for the vitamins involves the use of rats, guinea pigs, mice, or pigeons.In 1923, Steenbock, Sell, and Nelson pointed out the fact, which seems clear from their data, that in tests for vitamin B carried out with rats, considerable variation is found in the quantity of vitamin-containing material required for normal growth, depending on the method of caging the rats.When the experimental animals had access to their excreta, demonstrably smaller quantities of the vitamin-containing materials were required to bring about resumption of growth in the curative tests than when the rats were prevented from eating their feces.This indicated either that part of the ingested food factor was excreted unchanged or that the bacteria in the intestine synthesized the vitamin in the course of their growth processes.Corroborative studies on the rat have been made recently by Dutcher and Francis (1923-24), and Cowgill, Deuel, and Smith (1925) have given such findings a wider significance by their report of similar phenomena shown by the dog.This suggestion of improved technique made by the Wiscon-15