Pattern of trace elements in human milk during the course of lactation

In 79 human milk samples (days 1-293 post partum) from 46 healthy mothers 19 trace elements (Ba, Be, Bi, Cd, Co, Cs, Cu, Hg, La, Li, Mn, Mo, Pb, Rb, Sb, Sn, Sr, Tl, and Zn) were determined to investigate the concentrations of trace elements in human milk, the changes of elemental concentrations during the course of lactation and during the event of breast feeding. Except for cobalt, showing an 100% increase during the course of lactation, for essential trace elements (Cu, p < 0.005; Mn, p < 0.05; Mo, p < 0.0001 and Zn, p < 0.0001) a highly significant decrease in their concentrations in human milk could be observed. Generally, concentrations of toxic elements, such as Cd, Hg, and Tl decreased in early mature milk to 11 to 20% of the concentrations in colostrum, except Pb showing a much slower decrease. Concentrations of other elements of potential interest: such as Ba, Be, La, Li, and Sb were higher in colostrum than in mature milk. Trace elements, such as Bi, Cs, and Sr showed no change during the course of lactation. During an event of breast feeding concentrations of the essential trace elements Cu and Mo showed, a tendency to increase. Concentrations of Zn tended to decrease in transitory milk and to increase in mature milk during a single feed, whereas concentrations of Ba, Cs, Rb, and Sr decreased in human milk towards the end of an event of breast feeding. Our data indicate a fluctuation of up to 60% of the actual concentrations of Ela, Cs, Cu, Mo, Rb, and Sr in human milk during an event of breast feeding. Beside the time period of sampling, this fact has to be considered whenever milk samples are collected, to obtain comparable data about elemental concentrations in human milk. (C) 1998 Elsevier Science Inc.