NOW Nattokinase helps maintain normal blood flow.* Nattokinase is an enzyme isolated from natto, a traditional Japanese fermented soy food. Natto has been consumed for thousands of years for its numerous health promoting properties. More recently, both clinical and non-clinical studies have demonstrated that nattokinase can help to promote heart and circulatory health by supporting normal blood clotting functions.* NOW Nattokinase is derived from non-GMO soy and has 2,000 FUs (Fibrinolytic Units) per 100 mg serving.