Supplementation with vitamin E but not with vitamin C lowers lipid peroxidation in vivo in mildly hypercholesterolemic men.

Although the use of vitamin E supplements has been associated with a reduction in coronary events, assumed to be due to lowered lipid peroxidation, there are no previous long-term clinical trials into the effects of vitamin C or E supplementation on lipid peroxidation in vivo. Here, we have studied the long-term effects of vitamins C and E on plasma F2-isoprostanes, a widely used marker of lipid peroxidation in vivo. As a study cohort, a subset of the "Antioxidant Supplementation in Atherosclerosis Prevention" (ASAP) study was used. ASAP is a double-masked placebo-controlled randomized clinical trial to study the long-term effect of vitamin C (500 mg of slow release ascorbate daily), vitamin E (200 mg of D-alpha-tocopheryl acetate daily), both vitamins (CellaVie), or placebo on lipid peroxidation, atherosclerotic progression, blood pressure and myocardial infarction (n = 520 at baseline). Lipid peroxidation measurements were carried out in 100 consecutive men at entry and repeated at 12 months. The plasma F2-isoprostane concentration was lowered by 17.3% (95% CI 3.9-30.8%) in the vitamin E group (p = 0.006 for the change, as compared with the placebo group). On the contrary, vitamin C had no significant effect on plasma F2-isoprostanes as compared with the placebo group. There was also no interaction in the effect between these vitamins. In conclusion, long-term oral supplementation of clinically healthy, but hypercholesterolemic men, who have normal vitamin C and E levels with a reasonable dose of vitamin E lowers lipid peroxidation in vivo, but a relatively high dose of vitamin C does not. This observation may provide a mechanism for the observed ability of vitamin E supplements to prevent atherosclerosis.