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Published on: January 5, 2017
Antioxidant supplements for preventing gastrointestinal cancers
Goran Bjelakovic1, Dimitrinka Nikolova, Rosa G Simonetti
1Copenhagen Trial Unit, Centre for Clinical Intervention Research,, Department 3344, Rigshospitalet, Copenhagen University Hospital,, Blegdamsvej 9, Copenhagen, Denmark, DK-2100. goranb@junis.ni.ac.yu
The Cochrane Database of Systematic Reviews
|August 5, 2008
Summary
Antioxidant supplements do not prevent gastrointestinal cancers and may increase mortality. Selenium showed a potential benefit in some trials, warranting further investigation in well-designed studies.
Area of Science:
- Gastroenterology and Oncology
- Nutritional Science
- Evidence-Based Medicine
Background:
- Oxidative stress is implicated in gastrointestinal cancer development.
- Evidence regarding the efficacy of antioxidant supplements in preventing these cancers is conflicting.
Purpose of the Study:
- To evaluate the beneficial and harmful effects of antioxidant supplements for gastrointestinal cancer prevention.
- To synthesize findings from randomized controlled trials on antioxidant supplementation and gastrointestinal cancer risk.
Main Methods:
- Systematic review and meta-analysis of randomized controlled trials.
- Searched multiple databases including Cochrane, MEDLINE, EMBASE, LILACS, SCI-EXPANDED, and Chinese Biomedical Database.
- Extracted data on gastrointestinal cancers, overall mortality, and adverse effects; analyzed using random-effects and fixed-effect models.
Main Results:
- Twenty randomized trials (211,818 participants) assessed beta-carotene, vitamins A, C, E, and selenium.
- Antioxidant supplements showed no significant effect on gastrointestinal cancer incidence (RR 0.94, 95% CI 0.83-1.06).
- Significant heterogeneity was observed, potentially due to bias risk and supplement type; beta-carotene with vitamin A or E increased mortality, while selenium showed a potential protective effect in high-bias trials.
Conclusions:
- No convincing evidence supports antioxidant supplements for gastrointestinal cancer prevention.
- Antioxidant supplements may increase overall mortality.
- Further high-quality randomized trials are needed to investigate the potential cancer-preventive effects of selenium.
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