100% Natural. Soy Free. Supports Normal Circulatory Health. Suitable for Vegetarians. Nattokinase is a fibrinolytic enzyme which is extracted from the popular Japanese food natto. Natto is a cheese-like food that is produced by adding Bacillus natto to boiled non-gmo soybeans. . Nattokinase is to be used as part of your diet and exercise program to maintain normal circulatory health.