Natural Factors Nattokinase - is a fibrinolytic enzyme derived from whole natto concentrate to help support cardiovascular health. Natto is a traditional Japanese food made from fermented soybeans and is widely recognized for its health benefits. This formula features NSK-SD, a patented and highly purified form of nattokinase used in multiple clinical studies. It is made using non-GMO soybeans and has the naturally occurring vitamin K2 removed to avoid interactions with certain medications.