Natto is a Japanese fermented food, which originated from China. Soybeans are fermented by Bacillus subtilis and made into bean products. It is sticky, smelly and sweet. It not only retains the nutritional value of soybeans, but also is rich in vitamin K2, which improves the digestion and absorption rate of protein. More importantly, the fermentation process produces a variety of physiologically active substances, which have the health care functions of dissolving fibrin in the body and regulating physiological functions. The survey shows that Japanese people have been eating natto for more than 1 years.