Diet and sudden cardiac death.

The purpose of this paper is to review the evidence that dietary factors, namely the ingestion of the n-3 (or w-3) polyunsaturated fatty acids of fish oils can prevent fatal cardiac arrhythmias (so-called sudden cardiac death) in experimental animals, and probably in humans as well. The mechanism for this striking effect results from the ability of these fatty acids to directly stabilize electrically every contractile myocyte in the heart. This is accomplished by modulation by the free n-3 fatty acids of the ionic currents in heart cells; particularly the voltage-dependent sodium currents which initiate action potentials and the L-type calcium currents, which initiate release of sarcoplasmic reticulum stores of calcium into the cytosol of heart cells. The resultant rise in cytosolic calcium concentration initiates contraction of the heart cells and the beating rate of the heart. The gradually accumulating clinical evidence that these fish oil fatty acids are potent preventors of cardiac sudden death in humans will be reviewed. With some 250,000 deaths occurring within one hour of the onset of acute myocardial infarctions annually in the USA alone and millions more in the whole world, the potential large public health benefit from this understanding is evident.