Effect of supplementation with antioxidants upon long-term risk of hypertension in the SU.VI.MAX study: association with plasma antioxidant levels

OBJECTIVE: To assess the effects of supplementation with a combination of antioxidant vitamins and trace elements, at nutritional doses, upon the 6.5-year risk of hypertension in the SU.VI.MAX trial. To describe the association between baseline plasma antioxidant levels and the same long-term risk using observational data from the study. SETTING: A total of 5086 adults from the SU.VI.MAX trial, a randomized primary prevention trial. RESULTS: Compared with the placebo group, no effect of supplementation upon the 6.5-year risk of hypertension could be detected (odds ratio, 1.04 and 95% confidence interval, 0.87-1.23 in men; and odds ratio, 1.10 and 95% confidence interval, 0.95-1.29 in women). Furthermore, compared with men in the first tertile, those in the second and third tertiles of serum baseline levels of beta-carotene presented a lower risk of hypertension in both the placebo and supplementation groups. Multivariate-adjusted odds ratios (95% confidence interval) were 0.70 (0.44-1.12) and 0.53 (0.33-0.86) in the placebo group, and were 0.59 (0.37-0.94) and 0.67 (0.42-1.07) in the supplementation group. In women, a decreasing trend was observed with vitamin C levels and risk of hypertension in the intervention group. No association could be shown between vitamin E and trace element plasma levels and the risk of hypertension. CONCLUSIONS: Despite an inverse association between baseline plasma levels of beta-carotene in men and the risk of developing hypertension, we could not demonstrate any beneficial effect of low-dose antioxidant supplementation upon the 6.5-year risk of hypertension in the randomized analysis.