Associations of plasma omega-3 fatty acid levels and reported fish oil supplement use with depression and anxiety: A cross-sectional analysis from the UK Biobank

The role that marine omega-3 polyunsaturated fatty acids (PUFAs) may play in reducing the risk for developing depression and/or anxiety is unclear. The present study examined the relationships between plasma levels of total omega-3 PUFAs, docosahexaenoic acid (DHA) and the non-DHA omega-3 PUFAs with medical-record documented depression and/or anxiety (both historical and recent, within the last 12 months) in the UK Biobank. The associations of these outcomes with the reported use of fish oil supplements (FOS) were also examined. Data from 258,354 participants who had data on plasma omega-3 PUFA levels and all covariates were used for the biomarker-based analyses, and data from 468,145 people who reported FOS use at baseline were used in the latter analysis. We found that all three omega-3 PUFA metrics were inversely associated with a history of both depression and anxiety. Specifically, risk for the former outcome was between 15% and 33% lower in Q5 vs Q1, and for the latter outcome, between 19% to 22% lower comparing Q5 with Q1. Risk for recent depression was 29% and 32% lower (Q5 vs Q1) for total omega-3 PUFAs and for non-DHA, respectively. FOS use was associated with a 9-10% lower risk for a history of depression and anxiety, respectively, and a 20% lower risk for recent anxiety. In conclusion, we found evidence that higher levels of omega-3 PUFAs may play a protective role in depression and anxiety.