Vitamin E and red blood cell glutathione.

High doses of orally administered vitamin E (1000 IU/day) have been given to ten normal volunteers. Ten control subjects received placebo. Red blood cell glutathione was significantly higher in treated subjects than in the controls (controls: 267.5 +/- 15.7 micrograms/mL; treated: 374.8 +/- 17.3 micrograms/mL). These findings could be explained by an increase of glutathione synthesis brought about by the stimulation of glutathione synthetase activity. An alternative possibility is a reduced utilization of glutathione for the detoxification of free radicals. These two mechanisms could be effective in counteracting the glutathione content feedback of the synthetizing enzymes.