Dietary intake of long-chain n−3 polyunsaturated fatty acids and the risk of primary cardiac arrest

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Abstract
Whether the dietary intake of long-chain n−3 polyunsaturated fatty acids (PUFAs) from seafood reduces the risk of ischemic heart disease remains a source of controversy, in part because studies have yielded inconsistent findings. Results from experimental studies in animals suggest that recent dietary intake of long-chain n−3 PUFAs, compared with saturated and monounsaturated fats, reduces vulnerability to ventricular fibrillation, a life-threatening cardiac arrhythmia that is a major cause of ischemic heart disease mortality. Until recently, whether a similar effect of long-chain n−3 PUFAs from seafood occurred in humans was unknown. We summarize the findings from a population-based case-control study that showed that the dietary intake of long-chain n−3 PUFAs from seafood, measured both directly with a questionnaire and indirectly with a biomarker, is associated with a reduced risk of primary cardiac arrest in humans. The findings also suggest that 1) compared with no seafood intake, modest dietary intake of long-chain n−3 PUFAs from seafood (equivalent to 1 fatty fish meal/wk) is associated with a reduction in the risk of primary cardiac arrest; 2) compared with modest intake, higher intakes of these fatty acids are not associated with a further reduction in such risk; and 3) the reduced risk of primary cardiac arrest may be mediated, at least in part, by the effect of dietary n−3 PUFA intake on cell membrane fatty acid composition. These findings also may help to explain the apparent inconsistencies in earlier studies of long-chain n−3 PUFA intake and ischemic heart disease.