Omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been studied for their potential role in supporting or treating depression. Several observational studies have noted that populations with higher dietary intake of Omega-3s tend to have lower rates of depression. Randomized controlled trials (RCTs) and meta-analyses have shown mixed but generally modest positive effects, especially for EPA-rich formulations and in individuals with diagnosed major depressive disorder rather than mild symptoms or healthy individuals.

A 2016 meta-analysis in Translational Psychiatry and a 2019 umbrella review in Molecular Psychiatry concluded that Omega-3 supplementation, particularly with higher EPA content, may provide a small but statistically significant reduction in depressive symptoms compared to placebo, especially as an adjunct to standard antidepressant treatments. However, results are heterogeneous, with some studies showing little to no benefit.

The biological rationale for Omega-3s in depression includes their anti-inflammatory effects, influences on neurotransmitter function, and roles in neuronal membrane fluidity. Major psychiatric guidelines do not universally recommend Omega-3s as a first-line treatment, but some suggest they may be considered as adjunctive therapy. Overall, there is scientific evidence supporting a modest benefit, but more research is needed to clarify optimal dosing, formulation, and which patients may benefit most.