Protein Deficiency.—Animal protein is a superior protein and maize protein an inferior one. Wilson grades proteins according to their assimilability and taking meat protein as 1 he assigns to maize protein a relative value of 3.4, which means that one must consume 3.4 times as much maize protein as that of meat to obtain the necessary protein requirements. Thirty grams of animal protein daily is sufficient to maintain nitrogenous equilibrium but Wilson considers 40 as a minimum B. P. V. (Biological protein value). We should have to consume 136 grams of maize protein to obtain a B. P. value of 40. Where hard labour is required the B. P. V. should be 50 and when associated with chronic intestinal disease it should be as high as 60.
Wilson noted a B. P. V. of 23 for males in the diet which caused an outbreak of pellagra in Armenian refugees at Port Said. The diet of the pellagrous Turkish prisoners in Egypt had a B. P. V. of 33.5. It may be stated that zein, the protein of maize, is deficient in tryptophane and lysine, two important amino-acids necessary for proper nutrition. Chick apparently produced pellagra in a monkey fed on a low protein diet (Total protein 8.2 grams, of which all but 2.7 grams was from zein.). The monkey was given an abundance of accessory food substances in butter, marmite and orange juice.
Amino-acid Deficiency.—In a recent paper Goldberger and Tanner note that a low biological protein value is not necessarily indicative of a pellagra-producing diet. In a series of experiments the deficiency of vitamines did not seem to be related to pellagra production and the same was true of the mineral elements. In studying the nature of low protein biological values they were of the opinion that this rested in certain amino-acid deficiencies in the proteins consumed by the pellagrins. Benefit seemed to result from administering cystine to two cases of pellagra and in a third case there was steady improvement following the giving of both cystine and tryptophane.
It is a question whether zein, the principal protein of maize, contains any cystine.
Goldberger and his colleagues, after a careful investigation of pellagra epidemiology, decided that such facts as the complete absence of the disease among the nurses and attendants of the pellagrous insane, or among the prison guards of institutions where pellagra prevailed extensively, as well as among those caring for pellagrous orphans, indicated that a dietary factor rather than an infectious one was operative in the disease. Even where it was stated that attendants and inmates of institutions had the same dietary investigation indicated that as a matter of fact the insane and the prisoners were not as well fed as the other group. Then too the insane frequently fail to avail themselves of the food provided.
A study of the records of the Army and Navy of the United States failed to show that a single case of pellagra had ever developed among the personnel, although large numbers of the men came from pellagrous districts of the South. This exemption they thought due to the generous service ration.
In an investigation of the diet of the workingman’s family in the North and South it was found that the southern one consumed much larger quantities of starches and fats than the northern one, but less fresh meat. In the family of the cotton mill operative, a class showing a great incidence of pellagra, corn bread, flour biscuits, and fat pork were the chief articles of diet. There is a great deal of ancylostomiasis among these cotton mill people and the debilitating effect of this disease may predispose to pellagra. The general rise in the cost of food and, in particular, the disproportionate increase in price of meats over cereals, since 1907, may explain the greater incidence of the disease since that time. The wages of southern mill operators have also suffered on account of frequent periods of financial depression during the last ten years, thus causing them to buy cereals rather than meats.
Goldberger’s Experiment.—In February, 1915, Goldberger started a “pellagra squad,” consisting of 11 prisoners on a diet of wheat flour (patent), corn meal, corn grits, corn starch, polished rice, granulated sugar, cane syrup, sweet potatoes, fat fried out of salt pork, cabbage, collards, turnip greens and coffee. Baking powder was used for making biscuits and corn bread. The food value of each man’s diet averaged 2952 calories.
A control was carried out with prisoners on a normal diet. The experiment was continued until Oct. 31, 1915. Of the 11 volunteers on the excessive carbohydrate diet six developed symptoms. Loss of weight and strength and mild neurasthenia were early symptoms. Definite cutaneous manifestations appeared only after five months. The skin lesions were first noted on the scrotum, later appearing on backs of hands in two cases and back of neck in one case.