OBJECTIVE: This article is an overview of epidemiological and treatment studies suggesting that deficits in dietary-based omega-3 polyunsaturated fatty acids may make an etiological contribution to mood disorders and that supplementation with omega-3 fatty acids may provide a therapeutic strategy.

METHOD: Relevant published studies are detailed and considered.

RESULTS: Several epidemiological studies suggest covariation between seafood consumption and rates of mood disorders. Biological marker studies indicate deficits in omega-3 fatty acids in people with depressive disorders, while several treatment studies indicate therapeutic benefits from omega-3 supplementation. A similar contribution of omega-3 fatty acids to coronary artery disease may explain the well-described links between coronary artery disease and depression.

CONCLUSIONS: Deficits in omega-3 fatty acids have been identified as a contributing factor to mood disorders and offer a potential rational treatment approach. This review identifies a number of hypotheses and studies for consideration.

In particular, the authors argue for studies clarifying the efficacy of omega-3 supplementation for unipolar and bipolar depressive disorders, both as individual and augmentation treatment strategies, and for studies pursuing which omega-3 fatty acid, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), is likely to provide the greatest benefit.