Are omega-3 fatty acids efficacious in the treatment of depression? A review

Abstract

The hypothesis that omega-3 fatty acids may play a role in preventing and treating depression is based on correlative associations between fish consumption, omega-3 fatty acid intake and the prevalence of major depressive disorder. Reduced omega-3 fatty acid erythrocyte levels have been found in individuals with depressive disorders. These observational findings are unable to establish a causal relationship between omega-3 fatty acids and depression. The results of randomized controlled trials of omega-3 fatty acids for depressive disorders are inconclusive and also fail to prove causation. The therapeutic efficacy of omega-3 fatty acids appears to be moderate at best but is more likely to be minimal or non-existent. Potential long-term adverse effects of omega-3 fatty acid supplementation should be considered. Large-scale, well-controlled clinical trials are required to establish potential anti-depressive effects of omega-3 fatty acids. Such studies need to consider baseline values of omega-3 fatty acids and symptom severity, the dosage and types of the fatty acids used, the duration of supplementation and the concomitant use of medication. Conclusive evidence of the efficacy of omega-3 fatty acids in depression is currently lacking. The recommendation of potentially ineffective therapies may have considerable opportunity costs, with other possibly more useful treatments remaining unutilized.