2,000 FU Cardiovascular Health Helps Maintain Normal Blood Flow A Dietary Supplement Vegetarian / Vegan How it works: Nattokinase is an enzyme isolated from Natto, a traditional Japanese fermented soy food that 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 promote heart and circulatory health by helping to maintain normal blood fluidity. Each serving of Protocol For Life Balance Non-GMO Nattokinase has 2,000 FU (Fibrinolytic Units) for the maintenance of proper blood flow.