Vitamin E supplementation in patients with ischemic heart disease:: effect on in vitro LDL oxidation

The oxidative modification of low density lipoprotein (LDL) is accepted as an initial step in the pathogenesis of atherosclerosis. Antioxidants can increase the resistance of LDL to oxidation and hence reduce its atherogenicity. The objective of this study was to investigate whether in vivo supplementation of vitamin E can increase the oxidative resistance of LDL in patients with ischemic heart disease and a moderate hypercholesterolemia. Thirty-two patients (16 male patients and 16 postmenopausal women) participated in this placebo-controlled, randomized trial. Patients in placebo and vitamin E supplemented group (8 male patients and 8 postmenopausal women in every group) ingested placebo or vitamin E at a dose of 400 mg per day during 6 weeks. We compared the effects of vitamin E supplementation on the resistance of LDL to oxidation (lag time and maximal rate of oxidation) between male patients and postmenopausal women because of the observed different effects of vitamin E in both sexes. Plasma total and LDL cholesterol levels increased significantly in male patients after vitamin E supplementation (by 8% and 23%, respectively) when compared with postmenopausal women. The increase in plasma vitamin E levels after supplementation was also higher in male patients (by 87%) than in postmenopausal women (by 34%). In male patients six weeks of vitamin E supplementation prolonged significantly lag time by 33% (p = 0.002) and decreased the maximal rate of LDL oxidation by 13% (p = 0.008). In postmenopausal women the prolongation of lag time by 12% (p = 0.025) and no change in maximal rate of oxidation after supplementation with vitamin E were observed. A significant positive correlation between lag time and plasma vitamin E levels was found when male and female patients after vitamin E supplementation were evaluated as one group (r = 0.49; p = 0.007). Our results show a more favourable effect of vitamin E supplementation on in vitro LDL oxidation in male patients when compared with postmenopausal women. This observation could be helpful in selecting the appropriate dose of vitamin E in the prevention diseases from oxidative stress in patients of different sexes.