Habitual fish oil use and risk of COVID-19-related outcomes: Evidence from a large scale cohort study and Mendelian randomization analysis.

BACKGROUND & AIMS:Previous findings for the effects of fish oil on COVID-19-related outcomes remain largely inconclusive and controversy persists. Large population-based studies in real-life settings are required to explore the impact of habitual fish oil use on Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, Coronavirus disease 2019 (COVID-19)-related hospitalization and death. To investigate the associations between habitual fish oil use and SARS-CoV-2infection, COVID-19-related outcome. METHODS:Cohort study based on the UK Biobank. 466,572 participants were enrolled. For Mendelian randomization (MR) study, single-nucleotide variants were selected for exposures of fish-oil-derived n-3 PUFAs, including docosapentaenoic acid (DPA). RESULTS:146,969 (31.5%) participants reported their habitual fish oil use at baseline. Compared with non-fish-oil-users, the hazard ratios for habitual users were 0.97 (95% confidence interval [CI] 0.94 to 0.99) for SARS-CoV-2 infection, 0.92 (95% CI 0.85 to 0.98) for COVID-19-related hospitalization and 0.86 (95% CI 0.75 to 0.98) for COVID-19-related death. MR showed that a higher level of circulating DPA is casually associated with a lower risk of severe COVID-19 (IVW, odds ratio = 0.26, 95% CI 0.08-0.88, P = 0.030). CONCLUSIONS:In this large cohort, we found that habitual fish oil use was significantly associated with lower risks of SARS-CoV-2 infection, hospitalization and death from COVID-19. MR analyses further support a possible causal role of DPA, one of the components of fish oil and valid biomarkers of dietary intake, in reducing the risk of severe COVID-19.