The influence of stages of lactation on the mineral and trace element conce
ntrations of breast milk collected from 20 healthy lactating women in a Nig
eria population was investigated using instrumental neutron activation anal
ysis (INAA) and proton induced X-ray emission (PIXE) analysis. The breast m
ilk samples were divided into colostrum (day 1-5), transitional (day 6-13)
and mature milk (day 14-28). The result of the study show that colostrum mi
lk has a significantly higher mean concentration of Ca, Cl, Cu, Fe, Mg, Na
and Zn than the transitional and mature milk. Furthermore, the mean concent
rations of Fe, Mg, Na and Zn in transitional milk were found to be signific
antly higher when compared with the mature milk. It was also observed from
the serni-log plot of the concentration of the elements against days of lac
tation that the concentration of all the elements decreased significantly t
hroughout the lactation period studied with Cu, Fe and Zn concentration sho
wing the greatest decline, particularly in the early stages of lactation.