Selenium supplementation in healthy Belgian adults: response in platelet glutathione peroxidase activity and other blood indices.

Selenium status was explored by investigating effects of a 60-d Se supplementation with DL-selenomethionine (100 micrograms Se/d) in a group of 10 adults (plasma Se levels, 0.76-1.33 mumol/L). Plasma, erythrocyte, and urinary Se and activities of glutathione peroxidase (GSH Px) in plasma, erythrocytes, and platelets were measured before intervention and after 5, 15, 30, 45, and 60 d. A placebo was given to six adults. Plasma and urinary Se were the most sensitive indices to Se exposure. Se in plasma increased steadily during the course of the study whereas urinary Se reached a plateau between 30 and 60 d. By contrast erythrocyte Se did only change after 45 d. Enzyme in plasma and erythrocytes did not respond whereas platelet GSH Px did. The plateau of activity that was observed after 15 d for plasma Se in the range 1.40-1.50 mumol/L could mean that the Se status is insufficient for an optimal function of GSH Px and implies that dietary intake in Belgium (less than 50-60 micrograms Se/d) is not adequate.