Effects of long-chain omega-3 polyunsaturated fatty acids on reducing anxiety and/or depression in adults; A systematic review and meta-analysis of randomised controlled trials

First-line treatment for anxiety and depressive disorders comprises pharmacotherapy and psychotherapy; options not safe, effective, or suitable for all. Mounting evidence suggests that the omega-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic (EPA), docosahexaenoic (DHA) and docosapentaenoic (DPAn-3) acids are promising therapeutic options. However, meta-analyses of randomised controlled trials (RCTs) have produced inconsistent findings. This review assesses for the first time the efficacy of omega-3 PUFAs against the severity of anxiety and depression symptoms, measured by validated scales, with specific consideration of methodological issues encountered in this area. PubMed, CINAHL, PsycINFO, Cochrane Library and Web of Science were searched for eligible RCTs administering omega-3 PUFAs against anxiety and/or depression. This study adopts the PRISMA guidelines. Ten RCTs comprising 1509 participants were included in the quantitative synthesis. EPA-enriched interventions at [≥]60% of total EPA+DHA were associated with significant reduction in depression severity, compared to placebo (SMD: -0.32; 95% CI: -0.59, -0.06; p=0.02); however, EPA doses of [≥]2000 mg/day were not (SMD: -0.11; 95% CI: -0.43, 0.20; p=0.48). Only 10 RCTs fulfilled the eligibility criteria, and there were some concerns regarding bias and population heterogeneity, highlighting the lack of high-quality RCTs in this area. Overall, these results support previous observations where EPA at proportions [≥]60% of total EPA+DHA, up to 2000 mg, reduces depression scores. However, more trials are needed which specifically consider the unique nature of this type of research to elucidate the therapeutic potential of EPA, DHA and DPAn-3.