A total of 241 studies were identified, of which 28 were included for meta-analysis. Overall standardized mean depression scores were reduced in response to fish oil supplementation as compared with placebo (standardized mean difference -0.291, 95% CI -0.463 to -0.120, p = 0.001). Subgroup analyses showed significant effects for: (1) diagnostic category (bipolar disorder and major depression showing significant improvement with omega3 LC-PUFA supplementation versus mild-to-moderate depression, chronic fatigue and non-clinical populations not showing significant improvement); (2) therapeutic as opposed to preventive intervention; (3) adjunctive treatment as opposed to monotherapy; and (4) supplement type. Symptoms of depression were not significantly reduced in 3 studies using pure DHA (p= 0.997) or in 4 studies using supplements containing greater than 50% DHA (p = 0.417), but were significantly reduced in 13 studies using supplements containing greater than 50% EPA (standardized mean difference -0.446, 95% CI -0.753 to -0.138, p = 0.005) and in 8 studies using pure ethyl-EPA (standardized mean difference -0.396, 95% CI -0.650 to -0.141, p = 0.002). The current meta-analysis provides evidence that EPA may be more efficacious than DHA in treating depression. (J Am Coll Nutr. 2009 Oct;28(5):525-42.) PMID: 20439549.
