Nattokinase NSK-SD® 2000 FU. Isolated purified and encapsulated nattokinase an enzyme derived from boiled soybeans and a selected patented strain of Bacillus subtilis natto. Nattokinase NSK-SD® was the first nattokinase introduced into the US market and it has established standardization and quality levels for all nattokinase with comprehensive safety studies and proven potency. It is vegetarian non-irradiated and free of vitamin K2. NSK-SD® has two Japanese and three U.S. patents and is recognized by the JHFA (Japan Health and Nutrition Food Authorization) and JNKA (Japan Nattokinase Association) as authentic nattokinase. Each batch is tested to ensure potency. NSK-SD® is a trademark of Japan BioScience Laboratory.