The distribution of vitamin B2 in certain foods

BY vitamin B2 is here meant the factor in the vitamin B complex, other than the antineuritic, which promotes growth and cures and prevents dermatitis in rats.Its possible identity with the "P.P." factor, preventive and curative of human pellagra, and probably of " black-tongue " in dogs, is discussed later in this paper.Since the discovery that McCollum and Davis's [1915, 1, 2] water-soluble B vitamin can be subdivided into at least two factors, Eijkman's [1897] anti- neuritic and another [Smith and Hendrick, 1926; Goldberger et al., 1926; Chick and Roscoe, 1927], no attempt has been made to work out syste- matically the distribution of the more heat-stable factor, vitamin B2.The distribution of the other constituent, the antineuritic vitamin B1, as investi- gated by the power of a food to protect a bird on polished rice from poly- neuritis or to cure the condition when it is developed, is presumably not affected by the discovery of another factor in the vitamin B complex.As early as 1912 Cooper [1912] showed that pigeons require to maintain their weight on a diet of polished rice a factor different in its distribution from that which protects against and cures polyneuritis, and it is possible that this factor was what is here designated vitamin B2.But, since autoclaved yeast, one of the richest sources of vitamin B2, has no effect in curing polyneuritis, it would follow that the presence or absence of vitamin B2 in the food does not affect its strictly antineuritic potency.The distribution of the thermolabile anti- neuritic factor B1, in so far as it has been investigated by experiments with birds fed on polished rice, has therefore not been upset by later discoveries.Where the "water-soluble vitamin B" value of a substance has been investigated with the growth of rats as a criterion, it is not possible, since both factors are equally necessary for growth, to form any idea of the relative amounts of vitamins B1 and B2 present.Chick and Roscoe's [1928] work