Influence of variable quantities of methionine on nitrogen retention of adult human subjects.

T HAT the apparent requirement for a particular amino acid may be altered by the quantities of other essential amino acids present in the diet of human subjects has been demonstrated in a seriesof investigations related to lysine, isoleucine and ry’ The sulfur-containing amino acids also deserve consideration because they are present in relatively low concentration in certain legumes and nuts and are less abundant in milk and meat than in egg proteins.2 Methionine may be the limiting amino acid of greatest importance in economically developing countries.3 On the other hand, excess methionine is deleterious, at least in growing animals.4 The earlier series of experiments has now been extended to study the influence of different quantities of methionine on nitrogen retention of young men.