Efficacy of omega-3 fatty acids in mood disorders - a systematic review and metaanalysis

Existing efficacy trials of Omega-3 (omega-3) fatty acids in mood disorders have yielded inconsistent results. The current paper is an effort to provide a systematic review and meta-analysis to evaluate efficacy of omega-3 fatty acids in treatment of mood disorders.

We searched Medline, Embase, PsychInfo, and the Cochrane Controlled Trials registry up to June 2008 for randomized trials investigating efficacy of omega-3 fatty acids in mood disorders.We conducted random effects meta-analyses.We used the I2 statistic to quantify between-study inconsistency, and conducted pre-specified subgroup analyses to explore potential explanations for inconsistency.

We included 21 trials in our systematic review and found 13 trials to be eligible for meta-analysis. The pooled standardized mean difference in depressed mood states (n = 554 in 12 trials) was -0.47 (95% CI:-0.92,-0.02; I2 = 82.7; p = 0.07) and in manic mood states (n = 126 in 4 trials) was 0.22 (95% CI: -0.21, 0.65; I2 = 40.5; p = 0.31).We did not identify any treatment- subgroup interaction across forms of omega-3 fatty acids preparations (P = 0.99) or patient diagnosis (bipolar vs. unipolar depressive disorder; P = 0.96); there was a significant correlation between omega-3 fatty acids dose and treatment effect on depressive symptoms (r = 0.5, p = 0.04), but not on manic symptoms (P = 0.3).

The available evidence suggests that omega-3 fatty acids are a potential treatment of depressive disorders, but not mania. The unexplained between-study inconsistency and imprecision of the pooled estimates mitigate this suggestion. Large randomized placebo-controlled trials are needed to better estimate the value of this intervention for patients with depression.