BACKGROUND: n-3 Fatty acids are purported to have health effects in patients with inflammatory bowel disease (IBD), but studies have reported mixed results.

OBJECTIVE: We aimed to synthesize published and unpublished evidence to determine estimates of the effect of n-3 fatty acids on clinical outcomes in IBD and whether n-3 fatty acids modify the effects of or need for treatment with other agents.

DESIGN: Computerized databases were searched for studies of n-3 fatty acids in immune-mediated diseases from 1966 to 2003. We also contacted experts in the nutraceutical industry to identify unpublished studies; however, none were identified.

RESULTS: Reviewers identified 13 controlled trials that assessed the effects of n-3 fatty acids on clinical, sigmoidoscopic, or histologic scores; rates of induced remission or relapse; or requirements for steroids and other immunosuppressive agents in Crohn disease or ulcerative colitis. Most clinical trials were of good quality. Fewer than 6 were identified that assessed the effects of n-3 fatty acids on any single outcome of clinical, endoscopic, or histologic scores or remission or relapse rates. Consistent across 3 studies was the finding that n-3 fatty acids reduce corticosteroid requirements, although statistical significance was shown in only 1 of these studies.

CONCLUSION: The available data are insufficient to draw conclusions about the effects of n-3 fatty acids on clinical, endoscopic, or histologic scores or remission or relapse rates.