Omega-3 and polyunsaturated fat for prevention of depression and anxiety symptoms: systematic review and meta-analysis of randomised trials
What this study found
Increasing long-chain omega-3 supplementation probably has little or no effect on preventing depression symptoms, and it probably has little or no effect on anxiety symptoms as well. For depression prevention, the pooled risk ratio was 1.01 (95% CI 0.92 to 1.10; I2 = 0%), and a sensitivity analysis restricted to better adherence suggested possible increased risk (RR 1.16, 95% CI 0.99 to 1.36). In people with existing depression, evidence for change in severity or remission was very uncertain; one small trial showed a mean difference of -0.94 on the GDS-15 (95% CI -2.27 to 0.39; n = 61).…
- Study & population
- Systematic review and meta-analysis of randomized trials in adults aged 18 years and older, excluding pregnant or seriously ill people.
- Intervention
- This systematic review evaluated increasing long-chain omega-3 fatty acids, mainly EPA plus DHA, versus lower-dose or control regimens across randomized trials.
- Key limitation
- Evidence was sparse for several outcomes, especially depression treatment, ALA, omega-6, and total PUFA.
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Open PDFOriginal abstract
Background There is strong public belief that polyunsaturated fats protect against and ameliorate depression and anxiety. Aims To assess effects of increasing omega-3, omega-6 or total polyunsaturated fat on prevention and treatment of depression and anxiety symptoms. Method We searched widely (Central, Medline and EMBASE to April 2017, trial registers to September 2016, ongoing trials updated to August 2019), including trials of adults with or without depression or anxiety, randomised to increased omega-3, omega-6 or total polyunsaturated fat for ≥24 weeks, excluding multifactorial interventions. Inclusion, data extraction and risk of bias were assessed independently in duplicate, and authors contacted for further data. We used random-effects meta-analysis, sensitivity analyses, subgrouping and Grading of Recommendations, Assessment, Development and Evaluations (GRADE) assessment. Results We included 31 trials assessing effects of long-chain omega-3 (n = 41 470), one of alpha-linolenic acid (n = 4837), one of total polyunsaturated fat (n = 4997) and none of omega-6. Meta-analysis suggested that increasing long-chain omega-3 probably has little or no effect on risk of depression symptoms (risk ratio 1.01, 95% CI 0.92–1.10, I2 = 0%, median dose 0.95 g/d, duration 12 months) or anxiety symptoms (standardised mean difference 0.15, 95% CI 0.05–0.26, I2 = 0%, median dose 1.1 g/d, duration 6 months; both moderate-quality evidence). Evidence of effects on depression severity and remission in existing depression were unclear (very-low-quality evidence). Results did not differ by risk of bias, omega-3 dose, duration or nutrients replaced. Increasing alpha-linolenic acid by 2 g/d may increase risk of depression symptoms very slightly over 40 months (number needed to harm, 1000). Conclusions Long-chain omega-3 supplementation probably has little or no effect in preventing depression or anxiety symptoms. Declaration of interest L.H. and A.A. were funded to attend the World Health Organization Nutrition Guidance Expert Advisory Group (NUGAG) Subgroup on Diet and Health meetings and present review results. The authors report no other conflicts of interest.