DIETARY-INTAKE AND CELL-MEMBRANE LEVELS OF LONG-CHAIN N-3 POLYUNSATURATED FATTY-ACIDS AND THE RISK OF PRIMARY CARDIAC-ARREST

Objective.-To assess whether the dietary intake of long-chain n-3 poly unsaturated fatty acids from seafood, assessed both directly and indir ectly through a biomarker, is associated with a reduced risk of primar y cardiac arrest. Design.-Population-based case-control study. Setting .-Seattle and suburban King County, Washington, Participants.-A total of 334 case patients with primary cardiac arrest, aged 25 to 74 years, attended by paramedics during 1988 to 1994 and 493 population-based c ontrol cases and controls, matched for age and sex, randomly identifie d from the community. All cases and controls were free of prior clinic al heart disease, major comorbidity, and use of fish oil supplements. Measures of Exposure.-Spouses of case patients and control subjects we re interviewed to quantify dietary n-3 polyunsaturated fatty acid inta ke from seafood during the prior month and other clinical characterist ics. Blood specimens from 82 cases (collected in the field) and 108 co ntrols were analyzed to determine red blood cell membrane fatty acid c omposition, a biomarker of dietary n-3 polyunsaturated fatty acid inta ke. Results.-Compared with no dietary intake of eicosapentaenoic acid (C-20:5n-3) and docosahexaenoic acid (C-22:6n-3), an intake of 5.5 g o f n-3 fatty acids per month (the mean of the third quartile and the eq uivalent of one fatty fish meal per week) was associated with a 50% re duction in the risk of primary cardiac arrest (odds ratio [OR], 0.5; 9 5% confidence interval [CI], 0.4 to 0.8), after adjustment for potenti al confounding factors. Compared with a red blood cell membrane n-3 po lyunsaturated fatty acid level of 3.3% of total fatty acids (the mean of the lowest quartile), a red blood cell n-3 polyunsaturated fatty ac id level of 5.0% of total fatty acids (the mean of the third quartile) was associated with a 70% reduction in the risk of primary cardiac ar rest (OR, 0.3; 95% CI, 0.2 to 0.6). Conclusion.-Dietary intake of n-3 polyunsaturated fatty acids from seafood is associated with a reduced risk of primary cardiac arrest.