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Meta‐analysis: antioxidant supplements for primary and secondary prevention of colorectal adenoma
Author(s) -
BJELAKOVIC G.,
NAGORNI A.,
NIKOLOVA D.,
SIMONETTI R. G.,
BJELAKOVIC M.,
GLUUD C.
Publication year - 2006
Publication title -
alimentary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.308
H-Index - 177
eISSN - 1365-2036
pISSN - 0269-2813
DOI - 10.1111/j.1365-2036.2006.02970.x
Subject(s) - medicine , relative risk , colorectal adenoma , randomized controlled trial , adenoma , adverse effect , colorectal cancer , meta analysis , placebo , confidence interval , gastroenterology , cancer , pathology , alternative medicine
Summary Background Colorectal cancer may be prevented by reducing the development of adenomatous polyps. Aim To assess the benefits and harms of antioxidant supplements in preventing colorectal adenoma. Methods 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. Results 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). Conclusion We found no convincing evidence that antioxidant supplements have significant beneficial effect on primary or secondary prevention of colorectal adenoma.