Positive Health Online

Abstract

RIMM and STAMPFER, Department of Nutrition, Harvard School of Public Health, Boston MA 02115 USA write that vitamin C, carotenoids, and vitamin E, the 3 major dietary sources of antioxidants, each affect lipid peroxidation and may reduce atherogenesis and decrease the risk of coronary heart disease (CHD). Cross cultural studies of antioxidants find that areas with relatively low dietary antioxidant intake tend to have higher rates of CHD, but that it is difficult in these studies to account for other important risk factors. @r: The authors write that evidence from observational studies do not support a cardiovascular benefit for vitamin C, although the effect of vitamin C supplementation among populations with marginal vitamin C deficiency is not known. Beta-carotene supplementation shows not cardiovascular benefit, and several studies have found an inverse association between carotenoid intake or plasma levels and CHD risk. The benefit reported may be due to consumption of foods rich in beta-carotene rather than beta-carotene itself. The strongest evidence for a cardiovascular benefit of antioxidants is with vitamin E. Three large prospective studies found that vitamin E supplement users have about 40% lower rates of CHD. Short durations and doses of less than 100 IU/day have no significant effect. The effect of dietary vitamin E may be more modest but is still associated with lower risk of CHD in populations in which vitamin E supplementation is infrequent. In a large randomised trial, a nonsignificant reduction in CHD risk was reported for 50 IU/day, although may have been insufficient. A secondary prevention trial of 400 and 800 IU/day showed a strong reduction in nonfatal myocardial infarction, further supporting the large body of research evidence which demonstrates that high doses of vitamin E reduce risk of CHD.

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References

Rimm EB and Stampfer MJ. The role of antioxidants in preventive cardiology. Curr Opin Cardiol. 12(2): 188-94. Mar 1997. @i:25