CHANGHUA, TAIWAN. An ischemic stroke is caused by a blood clot or plaque fragment obstructing the flow of blood through the small arteries in the brain. A heart attack (myocardial infarction) is caused by a blood clot or plaque fragment obstructing the flow of blood through the small arteries feeding the heart. Venous thromboembolism, also known as deep vein thrombosis (DVT), is caused by a blood clot forming in the veins, most often in the lower legs.

Thus, inhibiting blood clot (thrombus) formation is of primary importance in the prevention of all the above conditions. The drug warfarin (Coumadin) is the most commonly used anticoagulant and works by inhibiting the activation of the vitamin K-dependent coagulation factors V, VII and X in the extrinsic and common pathways of the coagulation cascade. The level of other important coagulation promoters, such as fibrinogen and factor VIII, are not affected by warfarin.

Nattokinase, an extract from fermented soybeans (natto), is also known to inhibit blood clot formation (thrombosis), but does so by dissolving already formed fibrin-rich clots and by inactivating plasminogen activator inhibitor-1. Now researchers at the Changhua Christian Hospital in Taiwan report that nattokinase also inhibits the synthesis of fibrinogen and coagulation factors VII and VIII. Elevated fibrinogen levels are associated with increased blood viscosity and an increased risk of cardiovascular disease (CVD). There is also evidence that elevated levels of factors VII and VIII are associated with atherosclerosis and coronary heart disease.

The Changhua study involved 15 healthy controls, 15 patients with CVD or at least 2 risk factors for CVD, and 15 patients undergoing dialysis for chronic kidney disease (a known risk factor for CVD). At the beginning of the study (baseline) the levels of fibrinogen, factor VII and factor VIII in the three groups were as follows:

All study participants ingested 2 nattokinase capsules a day (2000 fibrinolysis units per capsule) for 2 months. At the end of this period levels of fibrinogen had decreased by 9% in the healthy group, by 7% in the CVD group, and by 10% in the dialysis group. Corresponding declines in factor VII level in the 3 groups were 14%, 13% and 7% and for factor VIII 17%, 19% and 19% respectively. No adverse events or increases in uric acid level were observed during the trial.

However, 18% of participants noticed a drop in blood pressure and/or increased vitality. Thirteen percent noticed an improvement in bowel function and 11% reported a lessening of shoulder-neck ache. The Taiwanese researchers conclude that supplementation with nattokinase would have a beneficial effect on risk factors associated with CVD through its reduction in fibrinogen, factor VII and factor VIII levels.

Hsia, CH, et al. Nattokinase decreases plasma levels of fibrinogen, factor VII, and factor VIII in human subjects. Nutrition Research, Vol. 29, 2009, pp. 190-96

Editor's comment: This study confirms that nattokinase is effective in preventing the formation of fibrin-rich blood clots such as those associated with venous thromboembolism and atrial fibrillation (blood stagnation in left atrium or left atrial appendage). Although nattokinase also reduces the level of factor VIII I am not aware of any evidence that it would also reduce the formation of platelet-rich clots (plaque). Additional evidence for the effectiveness of nattokinase in preventing DVT can be found in a study by a group of British and Italian researchers involving 204 airline passengers at high risk for venous thrombosis traveling between London and New York.[1]
[1] Cesarone, MR, et al. Prevention of venous thrombosis in long-haul flights with Flite Tabs. Angiology, Vol. 54, No. 5, Sept-Oct 2003, pp. 531-39