Use of antioxidant vitamins for the prevention of cardiovascular disease: meta-analysis of randomised trials

Introduction Oxidised LDL is thought to play an important part in the pathogenesis of atherosclerosis. Observational studies have associated α tocopherol (vitamin E), β carotene, or both, with reductions in cardiovascular events, but not clinical trials. We did a meta-analysis to assess the effect of these compounds on long-term cardiovascular mortality and morbidity. Methods We analysed seven randomised trials of vitamin E treatment and, separately, eight of β carotene treatment; all trials included 1000 or more patients. The dose range for vitamin E was 50–800 IU, and for β carotene was 15–50 mg. Follow-up ranged from 1•4 to 12•0 years. Findings The vitamin E trials involved a total of 81 788 patients and the p carotene trials 138 113 in the all-cause mortality analyses. Vitamin E did not provide benefit in mortality compared with control treatment (11•3 vs 11•1%, odds ratio 1•02 [95% Cl 0•98–1•06] p=0•42) or significantly decrease risk of cardiovascular death (6•0 vs 6•0%, p=0•86) or cerebrovascular accident (3•6 vs 3•5%, p=0•31). β carotene led to a small but significant increase in all-cause mortality (7•4 vs 7•0%, 1•07 [1•02–1•11] p=0•003) and with a slight increase in cardiovascular death (3•4 vs 3•1%, 1•1 [1•03-1•17] p=0•003). No significant heterogeneity was noted for any analysis. Interpretation The lack of a salutary effect was seen consistently for various doses of vitamins in diverse populations. Our results, combined with the lack of mechanistic data for efficacy of vitamin E, do not support the routine use of vitamin E.