Nattokinase NSK-SD® is a powerful fibrinolytic enzyme derived from the fermentation of non-GMO soybeans by Bacillus subtilis natto. Originally discovered for its strong systemic enzyme activity, it supports healthy circulation and normal clotting mechanisms.* NSK-SD® is standardized to be well tolerated and consistent in strength, free of vitamin K2, and backed by multiple patents and clinical research.* ARG offers Nattokinase NSK-SD in 100 mg (2000 FU) and 50 mg (1000 FU) strengths.