VITAMIN-B-12 LEVELS IN HUMAN-MILK DURING THE FIRST 9 MONTHS OF LACTATION

Vitamin B-12 concentration was measured by competitive binding radioas say in 48 samples of human milk from healthy mothers eating unrestrict ed diets, Specimens were collected 1-35 weeks after full-term delivery and were subjected to proteolytic digestion before radioassay in orde r to destroy binding proteins. The distribution of the results was ske wed, but the distribution of the logged values was not significantly d ifferent from normal, The geometric mean vitamin B-12 level remained a lmost unchanged during the first 12 weeks postpartum (261-297 pmol/l) and then declined to a low of 139 pmol/l at 27-35 weeks, A significant (P = 0.033) decline in vitamin B-12 concentration between 6-12 weeks and 19-25 weeks postpartum was observed.