Cclv. Experiments with Pigs on a Pellagra-producing Diet by Thomas William Birch', Harriette Chick and Charles

WHILE the rat has been used in recent years with great success in nutritional studies, the results obtained have proved to be misleading in the investigation of pellagra. Goldberger and his co-workers discovered that rats ceased to thrive, became ill and developed a symmetrical dermatitis when deprived of the heatstable portion of the B vitamin complex contained in yeast and concluded that this disease was probably the analogue of pellagra [Goldberger, Wheeler et al. 1926; Goldberger & Lillie, 1926]. Autoclaved dried yeast cured and prevented this rat disease and also canine "black tongue", the experimental disorder produced in dogs by feeding on diets consisting of 80% maize with addition of ample protein in the form of purified casein. For this reason the aetiology of this canine disease was considered by Goldberger and his school to be the same as that of human pellagra [Goldberger, Wheeler et al. 1926; 1928, 1, 2; Goldberger & Wheeler, 1928]. Spies [1934] has since shown that human pellagra can be cured by autoclaved dried yeast. Goldberger and his colleagues found the preventive factor or factors against canine black tongue and rat dermatitis to be present in an (autoclaved) aqueous extract of yeast and to be adsorbed on fuller's earth (at pH about 5-0). Goldberger's pellagra-preventive, or "P-P" solid, was prepared in this manner [Goldberger & Lillie, 1926; Goldberger, Wheeler et al. 1928, 1].Further investigation has, however, shown that this symmetrical dermatitis of rats has not the same causation as human pellagra or canine black tongue. The constituent of the heat-stable vitamin B2 complex, which has been found curative and preventive of this type of rat dermatitis (often known as "rat pellagra"), has been found present in whole maize and other cereals and to a less extent in the highly milled grains [Birch et al. 1935; Copping, 1936, 2; Dann, 1936]. It has been called vitamin B6 by Gyorgy and his colleagues. Lactoflavin, another constituent of the heat-stable vitamin B2 complex, is also water-soluble and adsorbed on fuller's earth. It is present in relatively large amounts in yeast, liver, milk and meat, the foodstuffs which have been found to have the greatest protective and curative effects in human pellagra and canine black tongue. Although necessary for health and growth of rats, it has proved to be neither curative nor preventive of this rat dermatitis; in fact the disorder has been found to be developed more regularly when pure lactoflavin is added to the experimental diet [Gyorgy, 1934; Chick et al. 1935; Copping, 1936, 1]. Further, treatment with pure lactoflavin has been without success in human pellagra [Dann, 1936] and in experimental canine black tongue [Birch et al. 1935; Koehn & Elvehjem, 1936; Sebrell, Hunt & Onstott, 1937]. Beit Memorial Fellow.