Abstract
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, IQ(5)R) 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 IQ(5)R = 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.