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

Whether the dietary intake of long-chain n-3 polyunsaturated fatty acids (P UFAs) from seafood reduces the risk of ischemic heart disease remains a sou rce of controversy, in part because studies have yielded inconsistent findi ngs. Results from experimental studies in animals suggest that recent dieta ry intake of long-chain n-3 PUFAs, compared with saturated and monounsatura ted fats, reduces vulnerability to ventricular fibrillation, a life-threate ning cardiac arrhythmia that is a major cause of ischemic heart disease mor tality. Until recently, whether a similar effect of long-chain n-3 PUFAs fr om 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 questionn aire and indirectly with a biomarker, is associated with a reduced risk of primary cardiac arrest in humans. The Endings also suggest that I) 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 reductio n in the risk of primary cardiac arrest; 2) compared with modest intake, hi gher intakes of these fatty acids are not associated with a further reducti on in such risk; and 3) the reduced risk of primary cardiac arrest may be m ediated, 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 t he apparent inconsistencies in earlier studies of long-chain n-3 PUFA intak e and ischemic heart disease.