Mortality in randomized trials of antioxidant supplements
- From: William Wagner <not-to-here-williamwag@xxxxxxxxx>
- Date: Tue, 15 May 2007 19:17:50 -0400
"CONCLUSIONS: Treatment with beta carotene, vitamin A, and vitamin E may
increase mortality. The potential roles of vitamin C and selenium on
mortality need further study."
.................................
JAMA. 2007 Feb 28;297(8):842-57.
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Mortality in randomized trials of antioxidant supplements for primary
and secondary prevention: systematic review and meta-analysis.
? Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C.
The Cochrane Hepato-Biliary Group, Copenhagen Trial Unit, Center for
Clinical Intervention Research, Copenhagen University Hospital,
Rigshospitalet, Copenhagen, Denmark. goranb@xxxxxxxxxxxxxx
CONTEXT: Antioxidant supplements are used for prevention of several
diseases. OBJECTIVE: To assess the effect of antioxidant supplements on
mortality in randomized primary and secondary prevention trials. DATA
SOURCES AND TRIAL SELECTION: We searched electronic databases and
bibliographies published by October 2005. All randomized trials
involving adults comparing beta carotene, vitamin A, vitamin C (ascorbic
acid), vitamin E, and selenium either singly or combined vs placebo or
vs no intervention were included in our analysis. Randomization,
blinding, and follow-up were considered markers of bias in the included
trials. The effect of antioxidant supplements on all-cause mortality was
analyzed with random-effects meta-analyses and reported as relative risk
(RR) with 95% confidence intervals (CIs). Meta-regression was used to
assess the effect of covariates across the trials. DATA EXTRACTION: We
included 68 randomized trials with 232 606 participants (385
publications). DATA SYNTHESIS: When all low- and high-bias risk trials
of antioxidant supplements were pooled together there was no significant
effect on mortality (RR, 1.02; 95% CI, 0.98-1.06). Multivariate
meta-regression analyses showed that low-bias risk trials (RR, 1.16; 95%
CI, 1.05-1.29) and selenium (RR, 0.998; 95% CI, 0.997-0.9995) were
significantly associated with mortality. In 47 low-bias trials with 180
938 participants, the antioxidant supplements significantly increased
mortality (RR, 1.05; 95% CI, 1.02-1.08). In low-bias risk trials, after
exclusion of selenium trials, beta carotene (RR, 1.07; 95% CI,
1.02-1.11), vitamin A (RR, 1.16; 95% CI, 1.10-1.24), and vitamin E (RR,
1.04; 95% CI, 1.01-1.07), singly or combined, significantly increased
mortality. Vitamin C and selenium had no significant effect on mortality.
CONCLUSIONS: Treatment with beta carotene, vitamin A, and vitamin E may
increase mortality. The potential roles of vitamin C and selenium on
mortality need further study.
PMID: 17327526 [PubMed - indexed for MEDLINE]
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