Toxic Effects of an Excess of Vitamin B 1 in Rats

Abstract

Summary

Additions of Mead Johnson's brewer's yeast in amounts equivalent to 50 I.U. of vitamin B₁ per animal per day will cause a marked increase in the weight curve for several generations. This amount of yeast, however, results in a disturbance in lactation and a loss of the nursing instinct evident in the first generation, but almost universal in the second generation, with consequent starvation of the young, and a high incidence of cannibalism. The effect was more pronounced in those animals fed B₁ concentrate (adsorbate). Among these, still-births were common as well. Synthetic vitamin B₁ was somewhat less toxic in excess amounts than the vitamin B₁ adsorbate but similar interference with lactation and the nursing instinct in the second generation occurred. It is interesting that vitamin B₁ in amounts equivalent to 40 times the maintenance requirement seems to have a similar effect in interfering with the capacity of the mother to rear her young and the nursing instinct as does a relative insufficiency of this vitamin. This should in no way discourage the generous use of vitamin B₁ in the diet of human beings, as the difference between the optimal requirement and the amount which may prove toxic after several generations is considerable. The excess amount given to our rats would be equivalent to the administration of between 5,000 and 10,000 I.U. of vitamin B₁ per day for several generations (assuming that the vitamin B₁ requirement of humans is between 100 and 200 units per day).

I am indebted to Mead Johnson for the supply of brewer's yeast for these and other experiments, to Eli Lilly for vitamin B₁ concentrate, and to Winthrop Chemical Company for the generous supply of Betaxin (synthetic vitamin B₁).