A substudy of the Alpha Omega Trial tested the hypothesis that omega-3 fatty acid supplementation will improve depressive symptoms and optimism. The three treatment groups that received either 400 mg/day EPA-DHA, and/or 2 g/day ALA and the placebo group of in total 4116 patients did not differ in baseline characteristics. Forty months of intervention with low-dose omega-3 fatty acid supplementation did not affect depressive symptoms and optimism.


We did not observe an effect of omega-3 fatty acid supplementation on either depressive symptoms or optimism. These results are in accord with those from earlier trials in individuals without psychopathology or without severe depressive symptoms.