Nattokinase may thin the blood and help break up blood clots. This might protect against heart disease and conditions caused by blood clots such as stroke, heart attack, and others. Blood thinners: Nattokinase may break up clots and thin out your blood. For this reason, nattokinase may worsen bleeding and bruising side effects of blood thinners,

Because of increasing interest rein nattokinase, methods of production that increase yield and stability have been explored. For example, irradiation of the bacterial strain B. subtilis natto Surgery: Nattokinase might increase the chance of bleeding during or after surgery. It might also make blood pressure difficult to control during surgery.