AMINO-ACID-COMPOSITION OF HUMAN-MILK IS NOT UNIQUE

To determine whether the amino acid pattern of human milk is unique, w e compared the amino acid pattern of human milk with the amino acid pa tterns of the milks of great apes (chimpanzee and gorilla), lower prim ates (baboon arid rhesus monkey) and nonprimates (cow, goat, sheep, Il ama, pig, horse, elephant, cat and rat). Amino acid pattern was define d as the relative proportion of each amino acid (protein-bound plus fr ee) (in mg) to the total amino acids (in g). Total amino acid concentr ation was lower in primate milk than in nonprimate milk. There were co mmonalities in the overall amino acid pattern of the milks of all spec ies sampled: the most abundant amino acids were glutamate (plus glutam ine, 20%), proline (10%) and leucine (10%). Essential amino acids were 40%, branched-chain amino acids 20%, and sulfur amino acids 4% of the total amino acids. The amino acid pattern of human milk was more simi lar to those of great apes than to those of lower primates.' For examp le, cystine was higher and methionine was lower in primate milks than in nonprimate milks, and in great ape and human milks than in lower pr imate milks. Because the milk amino acid patterns of the human and ele phant, both slow-growing species, were dissimilar, the amino acid patt ern of human milk seems unrelated to growth rate.