Effects of supplementation with high-selenium wheat bread on selenium, glutathione peroxidase and related enzymes in blood components of New Zealand residents.

The effects of supplementation with high-Se wheat bread on selenium (Se) concentrations, glutathione peroxidase (EC 1.11.1.9, GSHPx) activities and related enzymes in the prevention of lipid peroxidation were studied. Four New Zealand women were supplemented with 200 micrograms Se daily for 8-13 weeks followed by a post-dosing period of 9-12 weeks. GSHPx activities increased in whole blood, erythrocytes, plasma and platelets of all subjects but increases were considerably less than those of Se concentrations in whole blood, plasma and erythrocytes. During the post-dosing period Se concentrations and GSHPx activities fell to levels which were in most cases somewhat higher than baseline values. Glutathione-S-transferase activities in erythrocytes, plasma and platelets did not change during the study, nor did superoxide dismutase in erythrocytes and platelets, erythrocyte catalase or plasma alpha-tocopherol. Thus Se supplementation of healthy New Zealand subjects increased GSHPx activities but did not produce any adaptive changes in other components of the lipid peroxidation defense mechanisms.