McCOLLUM— RELATION OF DIET TO PELLAGRA. 51 



the diets of pellagrous families, and that calorific value of the diets 

 of the former households was somewhat higher than of the latter. 

 Animal proteins were eaten more liberally and cereal proteins were 

 eat<=^n less abundantly by the non-pellagrous than by the pellagrous 

 households. The pellagrous households had a distinctly smaller 

 supply of fat-soluble A, and a somewhat smaller supply of water- 

 soluble B than did the non-pellagrous, and the inorganic content of 

 the diets of the latter were of less satisfactory character than those 

 of the former households. We do not regard a moderate shortage 

 of one or another of the chemically unidentified dietary factors as 

 of greater gravity than faulty character in any other dietary factor. 

 Our studies of the several foodstufl:s lead us to agree with Gold- 

 berger's interpretation of the quality of the diets of pellagrous and 

 non-pellagrous households in all respects. 



From the observations which we have made concerning the 

 chemical factors which the diet must contain in order to be adequate 

 for the support of growth in the young, or the maintenance of phys- 

 iological well-being in the adult, together with the results of our 

 studies of the qualities of each of the more important kinds of nat- 

 ural foodstuffs, we are not able to account for the etiology of pel- 

 legra on the assumption that it is a disease which is due to the lack 

 of a specific substance or substances of unknown chemical nature, 

 as are without question beri-beri and xerophthalmia. This follows 

 from the fact that, with the exceptions of certain manufactured food 

 products which are derived from the endosperm of the decorticated 

 grains, any natural foodstuffs of the class of seeds, tubers, edible 

 roots, or leafy parts of the plant, are so constituted that they can be 

 supplemented by means of three kinds of purified food additions of 

 known nature : viz., protein, certain salts, and fat-soluble A, so as 

 to be complete for the nutrition of the young rat throughout the 

 growing period. This has been demonstrated to be true not only 

 for each of the ordinary human foods but likewise for such mixtures 

 as form the monotonous diets of the pellagrous. 



It is necessary, therefore, that we choose between two alterna- 

 tives in arriving at an opinion concerning the etiology of pellagra. 

 We have the assurances of Goldberger and his associates that a diet 

 such as that described on page 49, and having the qualities described 



