Comparison 1. Antioxidants versus placebo or no intervention.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mortality in trials with a low or high risk of bias	78	296707	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.98, 1.05]
1.1 Trials with low risk of bias	56	244056	Risk Ratio (M‐H, Random, 95% CI)	1.04 [1.01, 1.07]
1.2 Trials with high risk of bias	22	52651	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.85, 0.98]
2 Mortality in 76 trials with a low or high risk of bias with assigned fatalities to all of the dropouts	76	263805	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.99, 1.03]
2.1 Trials with low risk of bias	55	240738	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.99, 1.04]
2.2 Trials with high risk of bias	21	23067	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.86, 0.99]
3 Mortality in primary and secondary prevention trials with a low or high risk of bias	78	296707	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.98, 1.05]
3.1 Primary prevention trials with a low risk of bias	19	177868	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.97, 1.08]
3.2 Secondary prevention trials with a low risk of bias	37	66188	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.99, 1.07]
3.3 Primary prevention trials with a high risk of bias	7	38032	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.84, 1.03]
3.4 Secondary prevention trials with a high risk of bias	15	14619	Risk Ratio (M‐H, Random, 95% CI)	0.90 [0.81, 0.99]
4 Mortality after excluding trials administrating extra supplements in the antioxidant group	60	249526	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.99, 1.06]
4.1 Trials with low risk of bias	43	227700	Risk Ratio (M‐H, Random, 95% CI)	1.04 [1.01, 1.07]
4.2 Trials with high risk of bias	17	21826	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.82, 1.00]
5 Mortality after excluding trials with extra supplements for both intervention groups	63	283619	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.99, 1.05]
5.1 Trials with low risk of bias	48	233249	Risk Ratio (M‐H, Random, 95% CI)	1.04 [1.00, 1.07]
5.2 Trials with high risk of bias	15	50370	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.86, 1.00]
6 Mortality after excluding factorial trials with potential confounding	52	60544	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.94, 1.08]
6.1 Trials with low risk of bias	38	52955	Risk Ratio (M‐H, Random, 95% CI)	1.10 [1.05, 1.15]
6.2 Trials with high risk of bias	14	7589	Risk Ratio (M‐H, Random, 95% CI)	0.84 [0.73, 0.97]
7 Mortality after excluding factorial trials with potential confounding and trials with extra supplements	36	53542	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.92, 1.11]
7.1 Trials with low risk of bias	27	46783	Risk Ratio (M‐H, Random, 95% CI)	1.12 [1.06, 1.18]
7.2 Trials with a high risk of bias	9	6759	Risk Ratio (M‐H, Random, 95% CI)	0.84 [0.73, 0.98]
8 Mortality in beta‐carotene trials with a low or high risk of bias	31	195503	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.98, 1.07]
8.1 Trials with a low risk of bias	26	173006	Risk Ratio (M‐H, Random, 95% CI)	1.05 [1.01, 1.09]
8.2 Trials with a high risk of bias	5	22497	Risk Ratio (M‐H, Random, 95% CI)	0.81 [0.62, 1.07]
9 Mortality in vitamin A trials with a low or high risk of bias	18	61190	Risk Ratio (M‐H, Random, 95% CI)	1.04 [0.96, 1.13]
9.1 Trials with a low risk of bias	12	41144	Risk Ratio (M‐H, Random, 95% CI)	1.07 [0.97, 1.18]
9.2 Trials with a high risk of bias	6	20046	Risk Ratio (M‐H, Random, 95% CI)	0.96 [0.85, 1.07]
10 Mortality in vitamin C trials with a low or high risk of bias	41	90191	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.97, 1.05]
10.1 Trials with a low risk of bias	29	65942	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.98, 1.07]
10.2 Trials with a high risk of bias	12	24249	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.84, 1.04]
11 Mortality in vitamin E trials with a low or high risk of bias	64	211957	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.99, 1.04]
11.1 Trials with a low risk of bias	46	171244	Risk Ratio (M‐H, Random, 95% CI)	1.03 [1.00, 1.05]
11.2 Trials with a high risk of bias	18	40713	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.85, 0.99]
12 Mortality in selenium trials with a low or high risk of bias	24	86150	Risk Ratio (M‐H, Random, 95% CI)	0.96 [0.91, 1.01]
12.1 Trials with a low risk of bias	17	62740	Risk Ratio (M‐H, Random, 95% CI)	0.97 [0.91, 1.03]
12.2 Trials with a high risk of bias	7	23410	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.81, 1.01]