Nattokinase is an enzyme extracte and purified from a Japanese food called Natto. Natto is a cheese-like food made from fermented soybeans that has been eaten in Japan for many years. It is thought by some to be a valuable tool in minimizing the chances of developing heart and vascular diseases. Natto is produced by fermentation by adding the bacterium Bacillus natto, a beneficial bacteria, to boiled soybeans. The resulting nattokinase enzyme is produced when the bacterium acts on the soybeans. While other soy foods contain enzymes, it is only the natto preparation that contains the specific nattokinase enzyme. Nattokinase is valued in the alternative medicine community as a clot-buster and blood thinner, and is sometimes recommended as a substitute for daily aspirin therapy.