Clinical trials testing cardiovascular benefits of antioxidant supplementation

Self-selected supplementation of vitamin E has been associated with reduced coronary events and atherosclerotic progression, but the evidence from clinical trials is controversial. ASAP was a 6-year randomized trial to study the effect of supplementation with vitamin E plus slow-release vitamin C on carotid atherosclerotic progression in 520 hypercholesterolemic men and women aged 45-69 years. The supplementation reduced the progression of carotid atherosclerosis by 26% (P = 0.014), by 33% (P = 0.024) in men and 14% (not significant) in women. The effect was larger in subjects with low baseline vitamin C or atherosclerotic plaques. In the Harvard IVUS trial, the combined supplementation with vitamins E and C significantly inhibited the progression of coronary atherosclerosis in one year. These data confirm that the supplementation with a combination of vitamins E and C can retard atherosclerotic progression. The findings of completed trials testing the effect on cardiovascular events are less consistent. The major on-going clinical trials include the SU.VI.MAX, WHS, WACS and WAVE studies. These involve in total over 80,000 subjects, who are treated with antioxidative supplements for years. The results of these studies will become available during 2003-2006. They may provide the necessary additional information concerning the effect of antioxidants on cardiovascular events.