Effects of diet composition on coagulation pathways

Total dietary fat intake is an important determinant of factor VII coagulant activity, a hemostatic risk factor for fatal ischemic heart disease in middle-aged men. This association has a long-term effect by which a high-fat diet increases plasma factor VII antigen concentration, and an acute effect whereby a small proportion of factor VII is converted from its proenzyme to active serine protease for several hours postprandially. In adults whose usual diet is rich in long-chain saturated fatty acids, postprandial activation of factor VII occurs irrespective of the fatty acid composition. The underlying mechanism appears to require lipolysis and the presence of another coagulant protein, factor IX. There is limited evidence that factor VII activation after a meal rich in polyunsaturated fatty acid is blunted when the background diet also has a high content of polyunsaturated fatty acid. Meals rich in medium-chain triacylglycerols do not induce factor VII activation. The effects of dietary enrichment with n-3 fatty acids on factor VII are uncertain. All studies have been confined to the fasting state, and only one suggested changes consistent with factor VII activation. Fibrinogen concentration, another major hemostatic risk factor for ischemic heart disease, is uninfluenced by dietary fat content or composition, the one exception being inconsistent reports of a reduction after dietary enrichment with n-3 fatty acids. Overall, the evidence so far indicates that total dietary fat intake is more important than dietary fat composition for factor VII and by implication its attendant risk of fatal ischemic heart disease in high-risk populations.