Nattokinase 36mg 180 softgels from Source NaturalsNattokinase Systemic Enzyme For Healthy Circulation High Grade 'NSK SD' Brand Nattokinase Nattokinase is a systemic enzyme isolated from the traditional Japanese soy food natto. Source Naturals uses high grade 'NSK SD' brand Nattokinase. Nattokinase has been shown to support healthy blood flow by assisting in the circulatory clearing system of the body. Nattokinase Supports Healthy Circulation Nattokinase is a natural way to support healthy