Influence of dietary fat type on arterial thrombosis tendency.

Cardiovascular disease has a multifactorial aetiology, as is illustrated by the existence of numerous risk indicators, many of which can be influenced by the dietary fat type. It should be recalled, however, that only after a cause-and-effect relationship has been established between the disease and a given risk indicator (called a risk factor in that case), modifying this factor can be expected to affect disease morbidity and mortality. In this review, effects of dietary lipids on cardiovascular risk are considered, with special emphasis on modification of arterial thrombosis and platelet thrombotic processes, coagulation and fibrinolysis. Although epidemiological studies do not give entirely consistent results, replacement of dietary saturated by unsaturated fatty acids generally lowers cardiovascular morbidity and mortality. The few (secondary) prevention studies reported so far confirmed this for fish oil or fish oil concentrates, as well as for vegetable oils rich in oleic-, linoleic- or a-linolenic acids. Animal thrombosis models demonstrated that dietary unsaturated fatty acids reduce arterial thrombosis tendency as compared to saturated fatty acids. Using restenosis after percutaneous transluminal coronary angioplasty (PTCA) and occlusion of coronary artery bypass grafts (CABG) as human models of arterial thrombosis, fish oil treatment has been shown to have an anti-thrombotic effect, but results are inconsistent (PTCA) or need confirmation (CABG). Major thrombotic and anti-thrombotic conditions and processes include endothelial integrity, thrombotic functions of blood platelet, coagulation, and fibrinolysis. The dietary fat type can affect endothelial integrity, but results are inconsistent and often difficult to interpret in terms of arterial thrombosis tendency. The same can be concluded for platelet aggregation, especially because results of dietary interventions often depend on the aggregation measuring technique. Novel well-validated methods are required to solve this problem. Dietary fats can affect certain factors involved in blood coagulation and fibrinolysis. Thus, Factor VII activity is increased by the fat content of the diet. However, the dietary fat type seems of less importance. Studies addressing the effect of specific fatty acids on extrinsic clotting and thrombin formation in vivo did not produce consistent results. The same holds for the dietary fatty acid effects on promoters and inhibitors of the plasma fibrinolytic potential. Although trans unsaturated fatty acids may increase cardiovascular risk, this is probably not mediated by effects on arterial thrombosis.