Antioxidant supplements and mortality

Antioxidant supplements appear not to decrease mortality in healthy people or patients with chronic diseases. Beta carotene and vitamin E may increase the risk of death, and so may higher doses of vitamin A.

A Cochrane review included 78 studies with a total of 296 707 subjects. Overall, the antioxidant supplements had no significant effect on mortality in a random-effects meta-analysis (RR 1.02, 95% CI 0.98 to 1.05), but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). In 56 low-bias trials the antioxidant supplements significantly increased mortality (RR 1.04, 95% CI 1.01 to 1.07). In low-bias risk trials beta carotene (RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (RR 1.07, 95% CI 0.97 ti 1.18), vitamin C (RR 1.02, 95% CI 0.98 to 1.07), and selenium (RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002).

Comment: The quality of evidence is downgraded by inconsistency (variability in results across studies).

Ədəbiyyat

1. Bjelakovic G, Nikolova D, Gluud LL et al. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Database Syst Rev 2012;(3):CD007176. .