LONGITUDINAL-STUDY ON SELENIUM CONTENT IN HUMAN-MILK PARTICULARLY DURING EARLY LACTATION COMPARED TO THAT IN INFANT FORMULAS AND COWS MILK IN JAPAN

239 samples of human breast milk were collected from 36 healthy Japanese women. Selenium content of the samples was determined mainly by highly sensitive fluorometric analysis with 2,3-diaminonaphthalene. The highest selenium content, 247 mu g/kg, was found on the first day postpartum. The arithmetic mean of selenium content was higher in colostrum (<4 days) 47 mu g/kg (SD 42, n=116) than in transitional milk 24 mu g/kg (SD 13, n=87) or in mature milk (>10 days) 10 mu g/kg (SD 4, n=36). Selenium content was also determined for six brands of commercial infant formula powder (32-58 mu g/kg) based on cow's milk, seventeen brands of cow's milk (10-25 mu g/kg) and eight brands of powered cream for cofee (9-162 mu g/kg). The average selenium content was significant lower in the liquid formula prepared for infant lactation, 6.0 mu g/L, than in the human colostrum and transitional milk. The dietary selenium intake of newborns fed on colostrum is estimated to be in the range of 2-12 mu g per day.