Longitudinal changes in selenium content of breast milk.

The selenium (Se) contents of human milk, serum and hair obtained from 22 lactating mothers were measured by fluorometric analysis. The Se contents in 41 milk samples from different stages of lactation were obtained longitudinally from 10 mothers. They showed a large variance of individual samples at any stage of studies. The highest Se level was found in colostrum (median 80 ng/ml); subsequently, Se content declined significantly during the first month of lactation and then came to a plateau level (median 17-18 ng/ml). No positive correlation of Se content was found between the serum and the milk samples at three months of lactation. No positive correlation of Se content was found between the hair and the milk samples obtained from lactating mothers.