Coffee, caffeine and hemostasis: results from two randomized studies

Abstract

The influence of coffee and caffeine consumption on hemostatic factors was studied in 2 randomized trials. Both studies were conducted in young, healthy adults. In the first study, 107 participants were randomly allocated to one or 3 intervention groups, drinking filtered coffee, boiled coffee or no coffee at all, respectively, for a period of 9 weeks. In the second study, 69 subjects received either 4–6 tablets containing 75 mg caffeine or the same amount of placebo tablets, while using decaffeinated coffee. In this double-blind study caffeine intake from any other source was not allowed. Blood samples for hemostatic factors were obtained at baseline and after 9 weeks of intervention. The findings indicate no effect of coffee consumption on fibrinogen, clotting factor VII activity, factor VIII antigen, protein C and protein S and also no effect of caffeine consumption on fibrinogen and factor VII activity.