Use and misuse of dietary fatty acids for the prevention and treatment of coronary heart disease

Abstract - In the recent years, the health effects of fish (and n-3 fatty acids) have attracted considerable scientific interest. The present consensus is that the cardioprotection of very long chain n-3 fatty acids (also called EPA and DHA) at the low dosage used in recent secondary prevention trials primarily results from an effect on the ischemic myocardium and probably not from an effect on blood lipids and hemostasis. In other words, at these low dosages, there is apparently no major effect of these fatty acids on the progression of the vascular atherosclerotic lesions. In contrast, dietary alpha-linolenic acid (ALA), the parent compound of the very long chain n-3 fatty acids occurring in some vegetable oils, may be protective through mechanisms other than the myocardial (anti-arrhythmic) ones. In addition to its own direct preventive effect on cardiac arrhythmias, dietary ALA actually inhibits the elongation and desaturation of linoleic acid (18:2 n-6) into arachidonic acid. Because arachidonic acid (20:4 n-6) plays an important role in inflammation (as the precursor of the proinflammatory eicosanoids and leukotrienes), modifying its amount in blood and cell membranes influences the prevalence and severity of eicosanoid-related disorders, including atherosclerotic complications. The present knowledge of n-3 fatty acids justifies that physicians, in particular cardiologists in the context of secondary prevention of coronary heart disease, manage their patients, the young and the old, to increase their consumption of these fatty acids. They can only advise them to adequately adapt their diet (for instance in primary prevention), but in most cases, the systematic prescription of capsules containing oils enriched in ALA and EPA + DHA will be, ethically and scientifically, an obligation.