Meta-analysis: antioxidant supplements for primary and secondary prevention of colorectal adenoma
Article first published online: 26 JUN 2006
Alimentary Pharmacology & Therapeutics
Volume 24, Issue 2, pages 281–291, July 2006
How to Cite
BJELAKOVIC, G., NAGORNI, A., NIKOLOVA, D., SIMONETTI, R. G., BJELAKOVIC, M. and GLUUD, C. (2006), Meta-analysis: antioxidant supplements for primary and secondary prevention of colorectal adenoma. Alimentary Pharmacology & Therapeutics, 24: 281–291. doi: 10.1111/j.1365-2036.2006.02970.x
- Issue published online: 26 JUN 2006
- Article first published online: 26 JUN 2006
- Publication data Submitted 7 December 2005 First decision 6 March 2006 Resubmitted 19 April 2006 Accepted 21 April 2006
Colorectal cancer may be prevented by reducing the development of adenomatous polyps.
To assess the benefits and harms of antioxidant supplements in preventing colorectal adenoma.
Using the Cochrane Collaboration methodology we reviewed all randomized clinical trials comparing antioxidant supplements with placebo or no intervention. We searched electronic databases and the reference lists until October 2005. Outcome measures were development of colorectal adenoma adverse events. We analysed dichotomous outcomes with fixed- and random-effects model meta-analyses and calculated the relative risk with 95% confidence interval.
We identified eight randomized trials (17 620 participants). Neither fixed-effect (relative risk: 0.93, 95% CI: 0.81–1.1) nor random-effect model meta-analyses (0.82, 0.60–1.1) showed statistically significant effects of supplementation with β-carotene, vitamins A, C, E and selenium alone or in combination. Antioxidant supplements seemed to increase the development of colorectal adenoma in three low-bias risk trials (1.2, 0.99–1.4) and significantly decrease its development in five high-bias risk trials (0.59, 0.47–0.74). The estimates difference is significant (P < 0.0001). There was no significant difference between the intervention groups regarding adverse events, including mortality (0.82, 0.47–1.4).
We found no convincing evidence that antioxidant supplements have significant beneficial effect on primary or secondary prevention of colorectal adenoma.