Nattokinase is an extracelluar enzyme secreted by the bacterium Bacillus subtilis, used to ferment boiled or steamed soybeans resulting in a preparation called nattō.
Nattō has been consumed as food in Japan for several centuries.
Nattokinase is also available as a supplement and is most known for its fibrinolytic and thrombolytic effects. A few studies have explored its antihypertensive and amyloid-plaque degrading abilities (1) (2) (3) (4) (5).
Nattokinase decreases platelet aggregation and thrombus formation in a dose-dependent fashion both in vitro and in vivo (6) (7). Reduced intimal thickening was observed in the femoral artery of rats that were fed a diet containing nattō (8).
In a randomized, double-blind, placebo-controlled human trial, nattokinase capsules reduced diastolic and systolic blood pressure in pre-hypertensive patients (3).
The observation that nattokinase degrades amyloid plaques (1) (9) led to an interest in exploring it as a treatment for Alzheimer's disease, which is characterized by accumulation of amyloid plaques.
Nattokinase has also been promoted as an alternative anticancer treatment based on the notion that it can help dissolve the fibrin coating around a tumor, and increase oxygen supply in the blood to inhibit cancer cell growth. However, these mechanisms have not been proven in humans.
Theoretically, nattokinase may increase the risk of bleeding when used with anticoagulant, antiplatelet and fibrinolytic drugs.
Raw nattō contains high levels of vitamin K that may interfere with the action of warfarin (15).