Supplementation of Cereal Proteins with Amino Acids

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Abstract
Six children recently recovered from severe protein malnutrition, ranging in age from one year, 5 months to 5 years, 9 months and in weight from 7.7 to 12.7 kg, were fed a simplified wheat diet in which the protein was contributed by both the flour and gluten from wheat, in 8 experiments. All of the children were fed 2 gm of protein and 80 to 100 Cal./kg of body weight/day; a vitamin and mineral capsule was also given. The effect of the addition of the limiting amino acids according to the FAO “reference protein” was measured in most cases using three three-day balance periods. Comparison of the essential amino acid pattern of the wheat basal diet to the FAO “reference protein” showed that the order of the limiting amino acids was: lysine, tryptophan, methionine, isoleucine, valine and threonine. The results supply further evidence that in the utilization of wheat protein, lysine is the most limiting amino acid, since in most of the cases described in this paper, its addition to the basal wheat diet produced a sustained nitrogen retention sometimes similar to that obtained with milk feeding or observed when the basal diet was supplemented with all of the limiting amino acids according to the pattern of the FAO “reference protein.” In one of two trials an improvement in nitrogen retention was obtained upon the addition of tryptophan to the lysine-supplemented diet. The refusal and vomiting of the diet fed and a reduction in nitrogen retention when the basal diet was supplemented with all the limiting amino acids except lysine, was further evidence of the importance of the lysine deficiency of wheat diets. For wheat protein, at least, the level of methionine in the FAO “reference protein” appeared to be too high since its addition did not improve nitrogen retention.