To-day few would dare to reject the array of experimentally established facts and deny the relation of beri-beri or scurvy to lack of some essential substances in the diet, or question that there is a high degree of specificity in the effects of the missing constituents which induce the development of these syndromes. Many, however, who consider themselves capable of passing sound critical judgment on health matters have attributed some of the nutritive disturbances seen in certain parts of Europe during the great war, to lack of sufficient fat in the diet when the latter was derived in great measure from cereals and potatoes, and have felt satisfied with thus disposing of the matter. In so doing they have ignored several other defects in such a restricted food supply which have within recent years become clearly demonstrated, but are still not generally understood. The experimental data discussed in earlier chapters leaves but small room for doubt that lack of fats, strictly speaking, had little or nothing to do with health conditions. It was a lack of the substance fat-soluble A, which certain fats of animal origin contain in abundance, but which vegetable fats and oils derived from oil-bearing seeds either lack entirely or at best supply but very inadequate amounts, which was responsible for such nutritive disturbances as could be attributed to lack of fats in the diet. This view is supported by the observation of Wells (1), who observed remarkable benefit through the administration of small amounts of cod liver oil to malnourished Roumanians whose eyes were damaged by faulty diet. In many places, it would doubtless have been possible under wise management, to have corrected the defect due to lack of fat-soluble A in the diet by a liberal use of leafy vegetables, although these contain no more fats than do the cereals.

There were operating at the same time to produce malnutrition, other factors essentially as important as the lack of fat-soluble A in the diets just described. These were a low intake of protein of relatively low biological value, and lack of sufficient amounts of certain mineral elements, especially calcium and phosphorus and a low anti-scorbutic value of the foods employed. These deficiencies were doubtless on a parity with lack of fat-soluble A in causing lowered vitality, ill-defined cravings of the appetite, gastro-intestinal disturbances, and interruption of growth and faulty skeletal development in children.