Promotes Circulatory Health, High Potency - 2,000 FU's of Activity,Vegetarian Formula Nattokinase is an enzyme isolated from Natto, a traditional Japanese fermented soy food. Natto has been consumed safely for thousands of years for its numerous health benefits. More recently, both clinical and non-clinical studies have demonstrated that Nattokinase supports heart health and promotes healthy circulation. Each serving of  Nattokinase provides 2000 FU (Fibrinolytic Units) to help maintain already healthy levels of blood clotting factors within a healthy range.