Nattokinase is a fibrinolytic enzyme known to support healthy circulation.* Natto, the Japanese food from which Nattokinase is extracted, is rich in Vitamin K2. However, this form of Vitamin K is incompatible with some anticoagulant medications. NATTO NSK MEGA™ (Nattokinase NSK-SD™) utilizes a patented process to remove Vitamin K and provide only the purest form of this beneficial enzyme.