Essential Amino Acid Requirements of Infants

Abstract

The tryptophan requirement of the normal infant has been studied, using the dietary procedures, metabolic and laboratory techniques employed in previously described studies of the essential amino acid requirements of infants.^1-4 Our subjects were 5 male and 2 female infants who remained in the hospital for social reasons and were 12 days to 3 months old when they were included in the study. Two of these infants were born prematurely, had made uneventful progress, and were discharged from the premature unit when they became subjects in the study. The feeding was kept isonitrogenous by the substitution of glycine for the tryptophan that was withdrawn. The nicotinic acid intake was 0.85 mg. daily; this is the amount contained in the vitamin B mixture used to supplement all our synthetic diets. Individual protocols of these babies follow. Case 1 (Fig. 1).—Boy. Birth weight 3,750 gm. He was 3 months old and