Numerous studies have investigated the influence of omega-3 fatty acids, especially EPA and DHA (docosahexaenoic acid) in those with depression. While various combinations of EPA and DHA have displayed positive effects on mood, those composed mainly of EPA have shown more consistent benefits compared to mainly-DHA formulations.
EPA and DHA are known to play distinct roles in neurological and immune function, and the results of several clinical trials suggest that an EPA-to-DHA intake ratio of about 2:1 or 3:1 may be more optimal for mood. Recent studies have employed a wide range of dosage levels for EPA and DHA with divergent results in mood-related outcomes, and efficacious dosage ranges for EPA and DHA in mood applications have not been defined.
This meta-analysis was designed to elucidate the separate contributions of EPA and DHA to the mood-related effects of omega-3 fatty acids and to identify their effective dose ranges. Researchers reviewed double-blind, randomized, controlled trials with clearly-defined dosages of EPA and DHA for defined intervention periods in adults with depression or depressive symptoms according to validated psychometric assessment. Omega-3 fatty acid supplements were defined as DHA-pure (100% DHA), DHA-major (≥60% DHA), EPA-pure (100% EPA), or EPA-major (≥60% EPA) according to their composition. Daily DHA dosages ranged from 120-2000 mg, while daily EPA dosages ranged from 180-4000 mg. Studies were assessed for bias, and data from those meeting all eligibility criteria were analyzed in a controlled process guided by Cochrane analysis standards. A total of 26 studies with 2160 participants were included in the meta-analysis.
EPA’s Impact on Mood
EPA and DHA each contribute to brain function and neuroprotection in unique ways. A growing body of evidence suggests that EPA may exert greater influence over immune-related mechanisms that target neurocognitive function and immune balance in adults, with significant mood benefits. Omega-3 fatty acid supplements providing ≤1 gram of EPA daily in formulations consisting of at least 60% EPA may provide the most consistent effect on mood.