Selenium content of breast milk sampled in 1978 and 1983 in Sweden.

Selenium in human milk sampled at different intervals after parturition was analyzed on two occasions five years apart. The selenium content of colostrum and transitional milk was higher than that of mature milk. Mature milk sampled in 1983 contained more selenium than mature milk sampled in 1978 (11.9 (0.8) vs. 9.4 (0.5) micrograms/l, mean (SD), p less than 0.01). The selenium and protein content in milk were positively correlated, which may be explained by the occurrence of seleno-amino acids in proteins. The selenium content was not correlated to that of tocopherol or of highly unsaturated fatty acids in mature milk. The values for the selenium content in human milk found here are lower than those previously reported from other countries.