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Omega 3 fatty acids (fish oil) for maintenance of remission in Crohn's disease

  • Conclusions changed
  • Review
  • Intervention

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Abstract

Background

The anti-inflammatory effects of n-3 (omega-3 fatty acids, fish oil) have been suggested to be beneficial in chronic inflammatory disorders such as inflammatory bowel disease.

Objectives

To systematically review the efficacy and safety of n-3 for maintenance of remission in Crohn's disease (CD).

Search methods

The following databases were searched from their inception without language restriction: Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Healthstar, PubMed, and ACP journal club. Experts were contacted for unpublished data.

Selection criteria

Randomized placebo-controlled trials (RCT) of n-3 for maintenance of remission in CD were included. Studies must have enrolled patients of any age group, who were in remission at the time of recruitment, and were followed for at least six months. The intervention must have been fish oil or n-3 given in pre-defined dosage. Co-interventions were allowed only if they were balanced between the study groups. The primary outcome was the relapse rate and secondary outcomes included change in disease activity scores, time to first relapse and adverse events.

Data collection and analysis

Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality using Jadad's criteria. Meta-analyses were performed using RevMan 4.2 software weighted by the Mantel-Haenszel method. Random or fixed effect models were used according to degree of heterogeneity and subgroup analyses were performed in an attempt to explore possible sources of heterogeneity.

Main results

Six studies were eligible for inclusion. There was a marginal significant benefit of n-3 therapy for maintaining remission (RR 0.77 0.; 95%CI 0.61 to 0.98; P = 0.03). However, the studies were both clinically and statistically heterogeneous (P = 0.03, I2 = 58%). Two large studies showed negative results. When considering the estimated rather than the observed 1-year relapse rate of these two studies, the benefit was no longer statistically significant (RR 0.59; 95% CI 0.34 to 1.03; P=0.06). A funnel plot suggested publication bias. No serious adverse events were recorded in any of the studies but in a pooled analyses there was a significantly higher rate of diarrhea (RR 1.36 95% CI 1.01 to 1.84) and symptoms of the upper gastrointestinal tract (RR 1.98 95% CI 1.38 to 2.85) in the n-3 treatment group.

Authors' conclusions

Omega 3 fatty acids are safe but probably ineffective for maintenance of remission in CD. The existing data do not support routine maintenance treatment of Crohn's disease with omega 3 fatty acids.

Plain language summary

Omega 3 fatty acids (fish oil) for maintenance of remission in Crohn's disease

Fish oil contains omega 3 fatty acids that may be beneficial in reducing inflammation, such as seen in the bowel of Crohn's disease patients. Randomized placebo-controlled studies that evaluated the effect of daily intake of capsules containing omega-3 fatty acids to maintain remission in Crohn's disease were reviewed. Six studies were included of which three reported a significant reduction in the 1-year rate of disease relapse in comparison with placebo (fake medicine). The two largest studies showed no benefit to omega-3 treatment. There were no serious side effects in any of the studies. Common side effects included unpleasant taste, bad breath, heartburn, nausea and diarrhea. Omega 3 fatty acids are probably not effective for maintenance of remission in Crohn's disease. The existing data do not support the use of omega 3 fatty acids for maintaining remission in Crohn's disease.

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