In 1948, we had occasion to undertake a series of nitrogen-balance experiments on African patients in Mulago hospital, with a view to assessing their state of nutrition with respect to protein. Some had been admitted to hospital suffering from severe hookworm anaemia, others with enlargement of the liver and spleen sufficient to bring them into hospital. Others bore the diagnosis simply of 'malnutrition'. They all gave a history, extending over years, of a diet grossly deficient in protein, and from which animal protein was almost absent. Malnutrition of the type encountered here differs from that seen in Europe and America in that very serious protein deficiency may accompany a diet of reasonable calorie value. Bayliss's dictum 'Take care of the calories, and the protein will take care of itself' is emphatically not true in this part of Africa. This is because the common carbohydrate staples, sweet potato, cassava, and plantain contain z % or less of protein.Accurate figures for food consumption among the general population are lacking, but the following data are of interest. They were calculated from figures in a report of a cost-of-living survey carried out by the East African Statistical Department (1952). The number of individuals (all adult male labourers) observed was I 10, and the period of observation 30 consecutive days, The daily food consumption was: protein 53 g, carbohydrate 525 g, fat 42 g. This provided 2647 Cal. Only 9 g of the protein were of animal origin. Neither milk, eggs, butter nor cheese were consumed.Our subjects all gave a history of a diet consisting mainly of sweet potato, cassava, or plantain. Groundnuts or beans or both were eaten about once weekly, meat or fish not more often than once monthly, and eggs, milk, or cheese were never consumed. Although, in the absence of diet surveys, we cannot say what proportion of the population live on a diet of this kind, it is quite certain that the type of case with which we have been dealing is extremely common, and examples can be obtained from the general wards of the hospital whenever required. We were not surprised to find that these subjects retained nitrogen when placed on a diet high in animal protein and calories. But as the period of observation extended, and the nitrogen retention continued, we began to realize that some mechanism or mechanisms, not hitherto clearly recognized, must be playing an important part. We have made a long series of observations on the haematology and serum protein of these subjects. We shall, however, confine ourselves in this paper to the question of nitrogen and phosphorus balances.https://www.cambridge.org/core/terms. https://doi