The absorption and retention of nitrogen from leaf protein by infants recovering from malnutrition.

In underdeveloped countries no source of protein can be neglected that is likely to be useful as human food. Duckworth and his colleagues have shown that leaf protein (LP) prepared by the method of Morrison & Pirie (1961) has good nutritive value for chicks, rats and pigs (Duckworth & Woodham, 1961; Duckworth, Hepburn & Woodham, 1961). These results were encouraging enough to justify trials on human subjects. Balance studies were therefore made on Jamaican infants recovering from malnutrition. To give LP as the sole source of nitrogen would not be realistic; it is more likely to be useful as one component of a vegetable protein supplement. In Jamaica the most readily available sources of protein, apart from green leaves, are legumes and coconuts. As a first step, however, LP was given in combination with milk protein. Dietary histories and surveys show that many Jamaican infants aged about I year receive an amount of protein from milk which, though inadequate, is not negligible-of the order of 0-5 g/kg body-weight daily. The practical question therefore seemed to be: can leaf protein be used as a supplement to marginal quantities of milk? To answer it, mixtures were given providing daily 3-5 g protein/kg body-weight, in which one-half to twothirds of the nitrogen was derived from LP and the remainder from milk. Two kinds of control diet were needed: diets providing an equal intake of protein but derived entirely from milk; and diets providing a marginal intake of protein from milk, without supplementary leaf protein. As far as possible, each subject was used as his own control, but each kind of comparison could not be made with every patient. The results obtained with low protein intakes are also of some interest in relation to the problem of protein requirements. This point is considered in more detail on P. 537. The criterion used in this work was that of N balance. In recent years balance studies and their interpretation have been subjected to much criticism, and some people have maintained that the method is of little or no value (Gordon & Ganzon, 1959). Therefore it seemed necessary in the discussion to examine as closely as possible the validity of the conclusions drawn from these measurements.