Natto and Its Active Ingredient Nattokinase A Potent and Safe Thrombolytic Agent

N atto is a traditional Japanese food made by boiling or steaming soybeans and fermenting them with the Bacillus subtilis natto. The bacillus bacteria activate a fermenting process that lends the beans their notoriously sour aroma, nutty flavor, and slippery texture. The Bacillus subtilis natto is a rod-shaped bacterium with a relatively high heat tolerance. Compared to other bacteria that have a maximum tolerance of 20o–30oC, Bacillus subtilis natto’s heat tolerance is 40o–50oC. While some researchers have theorized that natto may have prehistoric origins, it first became a part of the Japanese culture during the later part of the Edo Period (1600–1868). During this period, soybeans were packed in straw and buried underground for a week or more. A naturally occurring bacillus in the straw facilitated the soybean fermentation. The result was natto. The modern method of making natto, by injecting the bacillus, was first developed in Sendai.1 Today, natto is readily available in Japan; it is commonly sold at local grocery stores in portable polystyrene containers. In Japan, natto is prepared several ways, some of which include blended with wheat, miso, cabbage or egg; mixed in salads; as a vegetarian hamburger; or as a condiment. Further research suggests that similar foods exist in other regions of Asia. For instance, people in Nepal make a comparable fermented soybean product that they refer to as a natto triangle.* In 1987, Sumi et al. found that natto contained a potent fibrinolytic enzyme that they named nattokinase.2 In controlled trials, natto is prepared by adding Bacillus subtilis natto to steamed soybeans in polystyrene containers and then allowing the mixture to ferment for 24 hours at 37oC. The natto bacilli are used in a common delivered concentration of 1010 cells/g of dried bacilli powder.3