To the Editor: In a recent publication,1 Fomon et al have reported on the requirements of infants for methionine, valine, and leucine, based on growth and nitrogen balance studies on young infants fed a soya bean formula. They report adequate growth and nitrogen retention on intakes of these three amino acids which, by and large, were appreciably lower than figures for minimal requirements obtained by us2 on diets in which nitrogen was provided as a mixture of amino acids. They are inclined to attribute this difference to the form in which the nitrogen was supplied.
We should like to point out that other variables may have been responsible for the discrepancy between their results and ours. The criteria of normal growth and adequate nitrogen retention were not identical in the two sets of studies. We have regarded weight gain as unsatisfactory unless it was comparable to that of