Long-term pharmacologic doses of vitamin E only moderately affect the erythrocytes of patients with type 1 diabetes mellitus

In erythrocytes from diabetic patients, increased membrane lipid peroxidati on might lead to abnormalities in composition and function. To study this r elationship, we investigated the effects of a moderate pharmacologic dose o f vitamin E for 1 y on erythrocyte membrane peroxidation in vitro and on it s fatty acid composition, antioxidant capacity and theological function. In a random and double-blind manner, type 1 diabetic patients (n = 44) were a ssigned to the following two groups: Group S received 250 lu (168 mg) d-alp ha tocopherol 3 times daily for 1 y, Group P received placebo for 6 mo foll owed by d-alpha -tocopherol for an additional 6 mo. Variables were monitore d every 3 mo. After 3 mo of supplementation, serum vitamin E doubled (P < 0 .0005), thiobarbituric acid reactive substances in erythrocyte membranes in cubated with tert-butyl hydroperoxide decreased by 25% (P = 0.006) and the lagtime of fluorescence increased from 28 +/- 16 to 41 +/- 28 min (P = 0.02 8). Patients who did not respond to supplementation (13 of 44) had lower se rum lipids (P = 0.017) and body mass index (P = 0.024). We did not detect a ny significant effects of vitamin E supplementation on membrane lipid compo sition, antioxidant capacity or blood viscosity. Continuing supplementation for up to 1 y did not further affect serum vitamin E or membrane peroxidat ion. Stopping supplementation was followed by a return to inclusion values. These results show that the decrease in erythrocyte membrane peroxidation after vitamin E supplementation is moderate, saturable, reversible, restric ted to some individuals and has no detectable effect on erythrocyte composi tion and function.