What we learnt from randomized clinical trials and cohort studies of antioxidant vitamin? Focus on vitamin E and cardiovascular disease.

There is no doubt that oxidative stress is pivotally involved in the process of atherosclerosis. Thus antioxidants, particularly vitamin E, have been expected to retard the development of atherosclerosis. In fact, several cohort studies suggested reduced cardiovascular risk in persons taking vitamin E supplements. However, randomized clinical trials of vitamin E did not show any benefit of vitamin E supplementation in terms of prevention of coronary heart disease and death. Discrepancy between cohort studies and randomized clinical trials may be partly explained by difference in coronary risk in study participant. However, use of vitamin E supplementation in low risk population has not been justified yet.