Environmental influences on hemostasis and thrombosis. Diet and smoking.

High levels of factor VII coagulant activity (VIIc) and fibrinogen concentration are independently associated with an increased risk of acute coronary heart disease in middle-aged men. Studies have, therefore, been undertaken to determine the responsiveness of these hemostatic factors to changes in diet and smoking habit. Plasma VIIc increases acutely with an increase in total fat intake, but fibrinogen is unaffected. In the general community, men who have a high total fat intake for their body size tend to have a high VIIc level. Changes in the dietary ratio of saturated to polyunsaturated fat of up to 14 days' duration have no effect on factor VIIc or fibrinogen (there are conflicting reports on the influence of dietary very-long-chain polyunsaturated fatty acids on fibrinogen concentration). Cigarette smokers have a higher fibrinogen concentration than do nonsmokers, but their levels slowly revert toward those of nonsmokers when the habit is relinquished.