An Antithyrotoxic Factor for the Rat Not Identical with Vitamin B12.

Abstract

Growth was markedly reduced in hypothyroid rats fed purified rations containing casein as the dietary protein and sucrose as the dietary carbohydrate. The retardation in growth was completely counteracted by the administration of a water-insoluble fraction of liver. Crystalline vitamin B₁₂ was ineffective. The protective factor in liver is distinct from any of the known nutrients including vitamin B₁₂.