Nattokinase NSK-SD® is a unique enzyme fermented with a proprietary strain of Bacillus subtilis natto extracted from a traditional Japanese food called natto (fermented soybeans) for a potent, all-natural option to help support the health of the cardiovascular system. Nattokinase has fibrinolytic activity – it degrades a substance in our blood called fibrin. This is how it is able to support our overall cardiovascular health. Each capsule contains 100 mg of this powerful enzyme, equivalent to 2,000 Fibrinolytic Units. Unlike most nattokinase supplements, this unique formulation has the Vitamin K2 removed.