AbstractSupplemental selenium (Se) as selenate, selenomethionine, or Se‐enriched yeast at 100–200 μg Se/day causes an increase or prevents a decline in human milk selenium content during the first 6 months of lactation. In this study, we evaluated the impact of supplemental Se as sodium selenate at 20 μg/day, an amount that closely approximates the quantity of selenium lost daily via milk secretion. Lactating women (n = 23) provided dietary data and milk and plasma samples at 3 and 6 months postpartum. At 3 months postpartum, all women received a daily vitamin/mineral supplement that furnished 20 μg of Se as sodium selenate for 3 months. Mean Se intake from self‐selected diets was 111 ± 40 μg/day and did not differ between 3 and 6 months. Selenium supplementation increased milk Se from 3 (295 ± 18 nmol/L; 23 ± 7 ng/mL) to 6 months (417 ± 39 nmol/L; 32 ± 14 ng/mL) postpartum (P ≤ 0.01) and corresponding infant Se intakes from 12 μg/day to 20 μg/day. Maternal plasma Se concentration was 1.46 ± 0.42 μmol/L (115 ± 33 ng/mL) at 3 months and 1.76 ± 0.20 μmol/L (155 ± 16 ng/mL) at 6 months postpartum, but this apparent difference was not significantly different. Maternal supplemental Se at 20 μg/day caused a 41% increase in human milk Se and a corresponding 67% increase in infant Se intake. Data show that supplemental Se at or near the quantity secreted daily is sufficient to prevent a decline in human milk Se with advancing lactation. J. Trace Elem. Exp. Med. 15:191–199, 2002. © 2002 Wiley‐Liss, Inc.
