No effect of n-3 long-chain polyunsaturated fatty acid (EPA and DHA) supplementation on depressed mood and cognitive function: a randomised controlled trial
What this study found
EPA and DHA supplementation did not improve depressed mood or cognitive function over 12 weeks. For the primary DASS depression outcome, the week-12 adjusted difference was -1.0 (95% CI -2.83, 0.81; P = 0.27), indicating no statistically significant benefit versus placebo. Other mood-related measures were also null, including Beck Depression Inventory at week 12 (P = 0.44), General Health Questionnaire (P = 0.88), and STAXI state anger (P = 0.46). The overall conclusion was that n-3 long-chain polyunsaturated fatty acid supplementation produced no meaningful benefit, and meta-analysis…
- Study & population
- Randomized placebo-controlled trial in adults aged 18 to 70 years with mild to moderate depressive symptoms, recruited mainly from general practice surgeries and community settings in Bristol, United Kingdom.
- Intervention
- Participants took three capsules daily by mouth for 12 weeks.
- Key limitation
- The intervention lasted only 12 weeks, so longer-term effects were not assessed.
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Open PDFOriginal abstract
Low dietary intakes of the n-3 long-chain PUFA (LCPUFA) EPA and DHA are thought to be associated with increased risk for a variety of adverse outcomes, including some psychiatric disorders. Evidence from observational and intervention studies for a role of n-3 LCPUFA in depression is mixed, with some support for a benefit of EPA and/or DHA in major depressive illness. The present study was a double-blind randomised controlled trial that evaluated the effects of EPA+DHA supplementation (1·5 g/d) on mood and cognitive function in mild to moderately depressed individuals. Of 218 participants who entered the trial, 190 completed the planned 12 weeks intervention. Compliance, confirmed by plasma fatty acid concentrations, was good, but there was no evidence of a difference between supplemented and placebo groups in the primary outcome – namely, the depression subscale of the Depression Anxiety and Stress Scales at 12 weeks. Mean depression score was 8·4 for the EPA+DHA group and 9·6 for the placebo group, with an adjusted difference of − 1·0 (95 % CI − 2·8, 0·8; P = 0·27). Other measures of mood, mental health and cognitive function, including Beck Depression Inventory score and attentional bias toward threat words, were similarly little affected by the intervention. In conclusion, substantially increasing EPA+DHA intake for 3 months was found not to have beneficial or harmful effects on mood in mild to moderate depression. Adding the present result to a meta-analysis of previous relevant randomised controlled trial results confirmed an overall negligible benefit of n-3 LCPUFA supplementation for depressed mood.