Selenium status of lactating women is affected by the form of selenium consumed.

The impact of providing selenomethionine (2.7 mumol Se) or selenium-enriched yeast (2.9 mumol Se) on the selenium status of lactating and nonlactating women with customary intakes of approximately 1.3 mumol Se/d was studied. Plasma selenium declined in unsupplemented lactating women but not in nonlactating women. Selenomethionine increased plasma selenium in both lactating and nonlactating women whereas selenium-enriched yeast increased plasma selenium only in nonlactating women. Erythrocyte selenium concentration was not significantly modified by lactation. Plasma glutathione peroxidase (GPx) activity decreased with duration of lactation in unsupplemented women and selenomethionine or selenium-enriched yeast supplementation prevented the decline. Milk selenium declined markedly for 20 wk after parturition in unsupplemented women. Selenomethionine significantly increased milk selenium concentrations whereas selenium-enriched yeast prevented a decline. These results clearly show that the source of selenium provided to lactating women can significantly influence selected indexes of selenium status, including milk selenium concentration.