gamma-Glutamyltransferase in breast milk.

The activity of gamma-glutamyltransferase was measured in a series of human breast milk samples collected during the first post natal week. All the samples showed considerable gamma-glutamyltransferase activity. The mean level fell from 28.8 U/ml to 3.9 U/ml seven days later. There was a highly significant correlation between gamma-glutamyltransferase and the protein content of the samples studied.