In 1914 Goldberger (5) began an investigation of the factors operating in the etiology of pellagra. His studies have proven of the greatest significance in clearing up this problem. He noted the fact that in several institutions where pellagra was either epidemic or endemic among the inmates, the physicians, nurses and attendants were almost without exception immune to the disease. This indicated that contact with persons suffering from pellagra, or opportunity for transmission by bedbugs, with which such institutions are almost always infested, did not seem a satisfactory explanation for the transmission of the disease. In institutions where the food purchases were assumed to be alike for patients and attendants, it was pointed out by Goldberger, that the diets of the two groups were not comparable. The nurses and attendants, due to their favorable position, chose the best articles, and diverted certain foods to their own table where the amounts did not suffice for all. The patients were thus placed at a disadvantage in regard to the quality of their food. Thus where the meat and milk purchased for an insane asylum was inadequate, the tendency would be for the milk and the desirable cuts of meat to find their way to the table of the attendants, while the unattractive pieces of fat or gristle would be served to the patients. Physicians, nurses and attendants were also in a position to supplement the institutional diet in any manner they saw fit.

Goldberger gained the impression after an examination of the character of the dietaries of certain institutions where pellagra was of common occurrence, that more cereals and vegetables were used than in the dietaries of people in better financial circumstances who were practically immune to the disease. This led him to undertake a study of the possibility of preventing the disease in institutions by improving the dietary.

At that time nothing was understood of the peculiar nutritive properties of the different natural food-stuffs. These have become known through the systematic studies of individual foods by means of the biological method introduced in 1915 by Mc-Collum and Davis (6). Goldberger could therefore do nothing better than to conclude that by comparing the diets of persons who developed pellagra, with those of people living in the same region but remaining free from the disease, he could arrive at a conclusion as to the kind of modification of the former type which should be necessary to test the relation of the diet to the incidence of pellagra. It was apparent to him that the habitants who remained free from the disease, took a diet which contained much greater quantities of fresh meats, eggs and milk, than those among whom the incidence was high. The well-to-do part of the population maintained a distinctly better dietary throughout the year than did the poorer people, who with the seasons suffered much greater changes in their food supply. The winter diet of the latter would naturally be simpler and more monotonous than one which would be available for a moderate expenditure of money during the summer months. The recognition of the importance of seasonal variations in the diet as an etiological factor in pellagra was one of great importance. It is true, however, that while pellagra is in great measure confined to the poorer classes, and afflicts those who live in the less desirable parts of cities and villages, this is by no means always the case, for it occurs among the well-to-do, but much less commonly than among those who depend upon a daily wage. As will be seen later, this can best be accounted for as due to idiosyncrasies which lead the patients to make a faulty selection of foods.