n-6/n-3 Ratio of dietary fatty acids rather than hypercholesterolemia as the major risk factor for atherosclerosis and coronary heart disease

Abstract

Classic lipid nutrition for the prevention of chronic, elderly-onset diseases was apparently established before 1960, assuming that hypercholesterolemia is the major risk factor and that raising the polyunsaturated/saturated (P/S) ratio of dietary fatty acids is hypocholesterolemic. However, the hypocholesterolemic effect of linoleic acid (LA) was found to be transient. Furthermore, hypercholesterolemia itself is unlikely to be a serious risk factor for diseases in the elderly because serum cholesterol level is positively correlated with longevityl. Instead, a high n-6/n-3 ratio of dietary fatty acids was found to increase thrombotic tendency, decrease peripheral blood flow and lead to persistent inflammation, which was proposed to be the major risk factor for atherosclerosis and related diseases. Based on animal experiments and epidemiological studies, we recommend a reduction in the intake of LA from a current value of >6 en% to half, and a reduced n-6/n-3 ratio from the current value of >4 to 2. Simply decreasing LA intake would produce the recommended n-6 and n-3 fatty acid balance in Japan due to the typical Japanese diet, but both decreasing the intake of LA and increasing that of n-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is necessary in Western industrialized countries for the effective prevention of atherosclerosis and related diseases; as well as of apoplexy, allergic hyper- reactivity and cancers typical in Western populations.