Abstract
Many reports on the relationship between tryptophan (Trp) and niacin (NiA) have been published since Elvehjem and Goldsmith. Also the relationship between leucine (Leu) and NiA was studied by Gopalan et al. Goldsmith and Horwitt reported that 60 mg of Trp is equivalent to 1 mg of NiA. However, this ratio are not stationary. The relationship between Trp and NiA is affected when the physical conditions, the amount of Trp intake, caloric intake, and certain amino acid imbalances are varied. Gopalan et al. reported that excess intake of Leu induced the same biochemical effect in the human and other mammals as in pellagrin, and amino acid imbalance due to an excess of Leu has been suggested as a possible factor in the development of pellagra. On the other hand, Truswell et al. did not support the suggestion that a relative excess of Leu in the diet played a part in the pathogenesis of pellagra. In our experiments, there was not seen the same biochemical effect as in those of Gopalan et al., but a marked decrease of the plasma valine level was observed, when supplied large amounts of Leu.
