n-3 Fatty acids consumed from fish and risk of atrial fibrillation or flutter: the Danish Diet, Cancer, and Health Study.

BACKGROUND Experimental studies have shown that n-3 polyunsaturated fatty acids in fish may have antiarrhythmic properties. OBJECTIVE We examined the association between consumption of n-3 fatty acids from fish and risk of atrial fibrillation or flutter. DESIGN In a prospective cohort study of 47 949 participants (mean age: 56 y) in the Danish Diet, Cancer, and Health Study, we investigated the relation between the consumption of n-3 fatty acids from fish estimated from a detailed semiquantitative food questionnaire and risk of atrial fibrillation or flutter. The subjects were followed up in the Danish National Registry of Patients for the occurrence of atrial fibrillation or flutter and in the Danish Civil Registration System (vital status and emigration). The consumption of n-3 fatty acids from fish was analyzed as sex-specific quintiles with the use of Cox proportional hazards models. RESULTS During follow-up (x: 5.7 y), atrial fibrillation or flutter had developed in 556 subjects (374 men and 182 women). When the lowest quintile of n-3 fatty acids consumed from fish was used as a reference, the unadjusted hazard rate ratios in quintiles 2, 3, 4, and 5 were 0.93, 1.11, 1.10, and 1.44, respectively (P for trend = 0.001). The corresponding adjusted hazard rate ratios were 0.86, 1.08, 1.01, and 1.34 (P for trend = 0.006). Inclusion of information on the frequency of fatty fish consumption did not alter these associations. CONCLUSIONS Consumption of n-3 fatty acids from fish was not associated with a reduction in risk of atrial fibrillation or flutter. We cannot exclude the possibility of residual confounding caused by a lack of information on intake of fish-oil tablets.