Oct 6, 2015
RAND researchers conducted a systematic review that synthesized evidence from randomized controlled trials of omega-3 fatty acids — used adjunctively or as monotherapy — to provide estimates of their efficacy and safety in treating adults with major depressive disorder.
Outcomes of interest included changes in depressive symptomatology, quality of life, and adverse effects. Efficacy meta-analyses used the Hartung-Knapp-Sidik-Jonkman method for random-effects models. Quality of evidence was assessed using a modification of the Grades of Recommendation, Assessment, Development, and Evaluation (or GRADE) approach.
In total, 24 studies met inclusion criteria. All studies combined showed a small but significant effect of omega-3 fatty acids compared with placebo on depression scale scores and the proportion of treatment responders, but there was evidence of publication bias. Only two studies compared eicosapentaenoic acid (EPA) with docosahexaenoic acid (DHA) head to head. Pooling studies of EPA alone and those with a high EPA:DHA ratio revealed a significant effect on depression scale scores and on the proportion of treatment responders compared with placebo, but studies that administered DHA alone or a high DHA:EPA ratio showed no effect. Very few studies specified depression severity, and few studies assessed effects on quality of life. Omega-3 fatty acids were associated with an increased risk for mild gastrointestinal symptoms compared with placebo but not with other categories of mild adverse events or serious adverse events.
The omega-3 fatty acid EPA may have a small benefit in improving depression symptoms compared with placebo, with relatively minor gastrointestinal adverse events for adults with MDD, but the existing evidence base is weak.
Discussion and Conclusions
Evidence Table of Included Studies
Excluded Full-Text Articles
Depression Scale Standard Cut-Points
Funnel Plots for Comparisons with Publication Bias