Nattokinase, an enzyme, is extracted from natto. Natto is not a food that you would rush to your favorite restaurant and order because it is definitely an acquired taste. It is fermented soybeans that are quite sticky and have a pungent smell. According to tradition, Natto has been a major food in the Japanese diet for over a thousand years and it is considered a daily food staple. In Japan, it is sold in stores in packages. The Japanese populace generally serve it over rice. So why would anyone want to eat such a disgusting food? Many Japanese like it and believe that it is a source of protein with health benefits that include being effective in the prevention of heart attacks. It has proven to reduce blood clots because it acts as a blood thinner.