Background – Whilst in most cases changes in diet and lifestyle can account for the sharp increase in morbidity and mortality from cardiovascular disease (CVD) in many Asian countries, the relatively high incidence of CVD in Sri Lanka cannot be fully explained by traditional plasma lipid markers or by an excessive total fat intake. Nevertheless, an excessive intake of saturated fat derived primarily from coconut (oil/milk/flesh), and a low consumption of polyunsaturated fatty acids (PUFA) coupled with a background diet rich in highly digestible carbohydrates may promote vascular endothelial dysfunction leading to the development of CVD.
Objective – To evaluate the effect of dietary saturated fats on the vulnerability to cardiac arrhythmia in the rat. Design – Twelve weeks old rats were fed ad libitum the standard AIN-97 diets containing different dietary fats. The control diet contained 5% (w/w) fat from canola oil and the test diets were made by replacing canola oil with either lard, or a mixture of coconut oil (CO; 4.5% w/w) and sunflower oil (0.5%w/w). After a 3 month pre-feeding period, myocardial ischaemia was induced by temporary occlusion of the left anterior descending coronary artery. Parameters of cardiac arrhythmia including % incidence and duration of ventricular tachycardia (VT), ventricular fibrillation (VF) and arrhythmia score (AS) were calculated.
Outcomes – Compared to the control group, CO and lard diets resulted in significant increase in the duration (sec) of VT (1.9±0.8 control; 38.8±13.4 lard; 31.0±10.1 CO, P<0.01). VF was absent in the control group, compared to 58% (lard) and 91% in the CO group. The duration of VF and the % mortality from VF was also higher in the CO fed rats. The PUFA profile of myocardial phospholipids was unchanged by the dietary manipulation.
Conclusions – CO appears to have direct pro-arrhythmic actions in the rat model of cardiac arrhythmia and sudden cardiac death. Some of these actions may be elicited at the vascular endothelium level. Therefore, strategies directed at promoting vascular integrity and function may afford protection in such situations.
References – Abeywardena MY. Dietary fats, carbohydrates and vascular disease: Sri Lankan perspectives. Athereosclerosis 2003; 171:157-161. Abeywardena MY. Dietary fatty acids and cardiovascular disease: Modulation of non-lipid risk factors. 2006; In. Huan et al eds, Dietary Fats and Chronic Disease, AOCS Press (Champaign); pp 157-167.