Associations of habitual fish oil use with risk of SARS-CoV-2 infection and COVID-19-related outcomes in UK: national population based cohort study

ObjectivesTo prospectively investigate the associations of habitual fish oil use with Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, hospital admission, or mortality with Corona Virus Disease-19 (COVID-19) in a large-scale cohort. DesignProspective population-based cohort study. SettingUK Biobank. ParticipantsA total of 110 440 participants aged 37 -73 years who completed a questionnaire on supplement use, which included fish oil at baseline were enrolled between 2006 and 2010 and followed up until 2022. Main exposureAll participants filled out questionnaires about the habitual use of supplements, including fish oil. Main outcome measuresSARS-CoV-2 infection, COVID-19 hospital admission and COVID-19 mortality. ResultsAt baseline, 29 424 (26.6%) of the 110 440 participants reported habitual use of fish oil supplements. The multivariable adjusted hazard ratios for habitual users of fish oil versus non-users were 0.95 (0.93 to 0.98) for SARS-CoV-2 infection among participants with follow-up time less than 12.1 years but no significant associations were observed for participants with follow-up time more than 12.1 years. For COVID-19-related outcomes, the hazard ratios were 0.79 (95% confidence interval 0.71 to 0.88) for COVID-19 hospital admission and 0.72 (0.60 to 0.87) for COVID-19 mortality. For COVID-19-related outcomes, the association seemed to be stronger among those with longstanding illness. The Cox proportional hazard analysis after propensity-score matching yielded consistent results. ConclusionsHabitual fish oil supplement is associated with a lower risk of hospital admission and mortality with COVID-19, but not associated with SARS-CoV-2 infection in the population with more than 12.1 years of follow-up.