OMEGA-3 PUFAS REDUCE THE VULNERABILITY OF THE RAT-HEART TO ISCHEMIC ARRHYTHMIA IN THE PRESENCE OF A HIGH INTAKE OF SATURATED ANIMAL FAT

The effect of dietary lipids upon the development of cardiac arrhythmias has been studied in an animal model of Sudden Cardiac Death. Ischaemic arrhythmia in mature male rats was induced by occlusion of the coronary artery. After 44 weeks of feeding various lipid modified diets, it was demonstrated that complete substitution of omega-6 polyunsaturated fatty acids (PUFA's) for saturated animal fat produced great benefits in cardiac function; as the number of ventricular premature beats (VPB), and the incidence (%) and severity (duration in seconds) of both ventricular tachycardia (VT) and ventricular fibrillation (VF) were markedly reduced. However, when mixed diets containing additional saturated fat (SF) plus either sunflower seed oil (SSO) rich in omega-6 PUFA or fish oil (FO) containing omega-3 PUFA's were compared, it was apparent that the inclusion of a relatively small proportion of omega-3 PUFA's in the diet was of great benefit as no VF was recorded in this group, whereas a similar proportion of omega-6 PUFA added to a saturated fatty acid rich diet was without significant effect. As the mixed SF/PUFA diets were constructed to contain essentially similar proportions of both saturated and monounsaturated fatty acids, but with contrasting amounts of either omega-6 or omega-3 PUFA's, the benefits observed by the inclusion of omega-3 PUFA's in the diet were direct and not due to coincidental changes in other fatty acid components of the diets.