Objective: To determine the relationship between plasma omega-3 levels and incident atrial fibrillation (AF), and the association between fish oil supplement (FOS) use and risk for AF. Methods and Analysis: Recent studies in UK Biobank concluded that FOS use was associated with increased risk of incident AF. Conversely, a meta-analysis found inverse relationships between blood levels of omega-3 and AF risk. We performed a prospective observational study linking plasma omega-3 levels and reported FOS use with AF risk in UK Biobank. Among UK Biobank participants without prevalent AF, 261 108 had plasma omega-3 levels and 466 169 reported FOS use. The primary outcome was incident AF during follow-up (median 12.7 years). Multivariable-adjusted hazard ratios (HR, 95% confidence intervals, CI) for fatty acids were computed continuously (per inter-quintile range, IQ5R) and by quintile. Hazard ratios were computed for dichotomous fish oil supplement use. Results: Plasma omega-3 levels were inversely associated with incident AF (HR per IQ5R = 0.90, 95% CI 0.86, 0.93; HR=0.87 [0.83, 0.91] in quintile 5 vs quintile 1). Fish oil supplement use was reported by 31% of the cohort and was more common in older individuals. After adjusting for age as a continuous variable, no association was observed between fish oil supplement use and AF risk (HR=1.00; 95% CI 0.97, 1.02). Conclusion: Higher circulating omega-3 levels were linked to reduced AF risk in UK Biobank. Further, after age was adjusted for as a continuous variable, no association was found between fish oil supplement use and AF.

JHO holds an interest in Cardiotabs and WSH holds an interest in Omegaquant Analytics

This project was partially supported by the Richard Galamba Foundation.

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The data used in this study were obtained from the UKBiobank and are publicly available subject to the rules and policies of the UKBiobank.

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All data produced in the present study are available upon reasonable request to the authors but additional approval from the UKBiobank is necessary to utilize the original data.