Colorectal cancer may be prevented by reducing the development of adenomatous polyps.
Dr Bjelakovic and colleagues from Serbia and Montenegro assessed the benefits and harms of antioxidant supplements in preventing colorectal adenoma.
The research team reviewed all randomized clinical trials comparing antioxidant supplements with placebo or no intervention.
The researchers used the Cochrane Collaboration methodology and searched electronic databases and the reference lists until 2005.
The outcome measures included development of colorectal adenoma adverse events.
|Antioxidants increased colorectal adenoma in 3 low-bias risk trials|
|Alimentary Pharmacology & Therapeutics|
The team also analyzed dichotomous outcomes with fixed- and random-effects model meta-analyses.
The relative risk with 95% confidence interval was calculated.
The researchers identified 8 randomized trials with 17,620 participants.
Neither fixed- nor random-effect models showed significant effects of supplementation with ß-carotene, vitamins A, C, E and selenium alone or in combination.
The team found that antioxidant supplements seemed to increase the development of colorectal adenoma in 3 low-bias risk trials.
In addition, the team observed that antioxidant supplements significantly decreased colorectal adenoma development in 5 high-bias risk trials.
The estimates difference was significant.
The researchers noted no significant difference between the intervention groups regarding adverse events, including mortality.
Dr Bjeclakovic's team concluded, “Our team found no convincing evidence that antioxidant supplements have significant beneficial effect on primary or secondary prevention of colorectal adenoma.”