Nattokinase is an all-natural, potent enzyme that is extracted from natto and highly purified. Natto is a fermented soybean food that has been consumed in Japan for over 1000 years. Nattokinase has been the subject of many studies, including human and animal trials. In 1980, researchers discovered that nattokinase demonstrated a positive effect on blood flow in vitro. Nattokinase may also support cardiovascular health.