Omega 3 fatty acids for maintenance of remission in ulcerative colitis

Fish oil contains omega 3 fatty acids that may be beneficial in reducing inflammation, such as seen in the bowel of ulcerative colitis patients. Randomized placebo-controlled studies that evaluated the effect of daily intake of omega-3 fatty acids to maintain remission in ulcerative colitis were reviewed. Three studies were included of which none reported a reduction in the rate of disease relapse in comparison with placebo. When the studies were pooled for meta-analysis there was no benefit for omega 3 fatty acids. There were no serious side effects in any of the studies. None of the studies used enteric coated capsules which allow release of the fish oil in the small bowel. Non-enteric coated omega-3 fatty acids (fish oil) seem safe but ineffective for maintaining remission in ulcerative colitis. Further studies of enteric coated capsules may be justified.

Authors' conclusions: 

No evidence was found that supports the use of omega 3 fatty acids for maintenance of remission in UC. Further studies using enteric coated capsules may be justified.

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Background: 

Omega-3 fatty acids (n-3, fish oil) have been shown to have anti-inflammatory properties. Therefore, n-3 therapy may be beneficial in chronic inflammatory disorders such as ulcerative colitis.

Objectives: 

To systematically review the efficacy and safety of n-3 for maintaining remission in ulcerative colitis (UC).

Search strategy: 

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 Experts were contacted for unpublished data.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 fish oil for maintenance of remission in UC 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 given in pre-defined dosage. Co-interventions were allowed only if they were balanced between the study groups. The primary outcome was relapse rate and the secondary outcome was frequency of adverse events. Other outcomes to assess efficacy were change in disease activity scores and time to first relapse.

Data collection and analysis: 

Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality. Meta-analysis weighted by the Mantel-Haenszel method was performed using RevMan 4.2.8 software. Random or fixed effect models were used according to degree of heterogeneity and subgroup analyses were performed to explore heterogeneity. A sensitivity analysis was performed excluding a study of questionable quality .

Main results: 

The three studies that were included used different formulation and dosing of n-3 but none used enteric coated capsules. The pooled analysis showed a similar relapse rate in the n-3 treated patients and controls (RR 1.02; 95% CI 0.51 to 2.03; P = 0.96). Combining the studies resulted in virtually no statistical heterogeneity (P = 0.93, I2 = 0%). Various subgroup and sensitivity analyses showed similar results. However, the total number of patients enrolled in these studies was small (n = 138). No significant adverse events were recorded in any of the studies and not enough data were available to pool the other secondary outcomes for meta-analysis.

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