Meta-analysis: antioxidant supplements for primary and secondary prevention of colorectal adenoma

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#adult #aged #aged-80-and-over #antioxidants #colorectal-neoplasms

Meta-analysis: antioxidant supplements for primary and secondary prevention of colorectal adenoma

Bjelakovic et al., 2006 | Aliment Pharmacol Ther | Meta Analysis

Citation

Bjelakovic G, Nagorni A, ... Gluud C. Meta-analysis: antioxidant supplements for primary and secondary prevention of colorectal adenoma. Aliment Pharmacol Ther. 2006-Jul-15;24(2):281-91

Abstract

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 beta-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.

Key Findings

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 beta-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

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population See abstract
Sample Size 620
Age Range See abstract
Condition See abstract

MeSH Terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antioxidants
  • Colorectal Neoplasms
  • Dietary Supplements
  • Female
  • Humans
  • Male
  • Middle Aged
  • Randomized Controlled Trials as Topic
  • Treatment Outcome

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Research Support, Non-U.S. Gov't, Review
  • Vertical: selenium

Provenance

  • PMID: 16842454
  • DOI: (not available)
  • PMCID: Not in PMC
  • Verified: 2026-04-09 via PubMed E-utilities API

Source extracted via PubMed E-utilities API on 2026-04-09