Twelve RCTs were included. Seven RCTs (n=81,788) examined vitamin E and 8 RCTs (n=138,113) examined beta-carotene.
Vitamin E.
Over all studies, there was no statistically significant difference between vitamin E and control for all-cause mortality (OR 1.02, 95% CI: 0.98, 1.06, P=0.42), cardiovascular mortality (OR 1.0, 95% CI: 0.94, 1.06, P=0.94), or cerebrovascular accident (OR 1.02, 95% CI: 0.92, 1.12, P=0.71). No statistically significant heterogeneity was detected.
A subgroup analysis found no statistically significant difference between vitamin E and control for all-cause mortality among secondary or primary prevention studies. The results were similar after including 2 RCTs that did not meet the inclusion criterion for size.
No statistically significant difference was found between vitamin E and control for the combined outcome of cardiovascular death or nonfatal MI, but statistical heterogeneity was found (P=0.053).
Beta-carotene.
Beta-carotene was associated with a slight statistically significantly increase in all-cause mortality (OR 1.07, 95% CI: 1.02, 1.11, P=0.003) and cardiovascular death (OR 1.1, 95% CI: 1.03, 1.17, P=0.003) when compared with control. Based on 3 RCTs, there was no statistically significant difference between treatments for all-cause cerebrovascular accident (OR 1.0, 95% CI: 0.91, 1.09, P=0.92). No statistically significant heterogeneity was detected.