Fish oil may ward off 'sudden death.' (omega-3 fats fight ventricular fibrillation in monkeys) (Brief Article)

About 250,000 people in the United States die quickly and unexpectedly each year from heart disease. Much of this "sudden cardiac death" occurs when the heart% normally rhythmic pulsing turns inexplicably chaotic -- a condition known as ventricular fibrillation. Conditions that can predispose the heart to these arrhythmias include atherosclerosis, heart attack, congestive heart failure, use of certain drugs (even those prescribed to curb arrhythmias), and abnormal thickening of the heart muscle. People suffering from any of these might be advised to eat fish, a new study suggests.

Peter L. McLennan and his co-workers at Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) in Adelaide studied the effects of dietary fat on a monkey's susceptibility to ventricular fibrillation. The CSIRO team fed 20 adult marmosets diets in which 31 percent of the calories came from fat -an amount typical of most human diets in Western industrialized countries. While holding the saturated- and monounsaturated-fat content constant, the researchers varied the type of polyunsaturates in the diet. Half of the monkeys received their polyunsaturates as omega-6 fats from sunflower oil, half as omega-3 fats from fish oil.

After 16 weeks, the researchers delivered electrical pulses to the heart of each animal and measured the threshold current needed to induce a ventricular defibrillation, Under normal conditions, monkeys fed sunflower-oil diets experienced arrhythmias at currents equal to half those needed to induce heart flutters in animals fed fish oil. Even when the researchers cut off oxygen to the heart -- a condition that occurs during heart attacks - the fish-oil-fed animals withstood the destabilizing currents much better, the team reports in the November AMERICAN JOURNAL OF CLINICAL NUTRITION.

These data indicate not only that omega-3 fats are preferentially incorporated over omega-6 fats into heart muscle, but also that omega-3 fats are more potent arrhythmia fighters, the group says. Moreover, the CSIRO scientists note that the fish-oil concentrations in this study, while relatively high, "approached those that might be achieved in a Western diet."