The existence of a potent fibrinolytic enzyme (nattokinase, NK) in the traditional fermented food called "natto", was previously reported (Sumi et al., Experimentia 43: 1110, 1987). In this present study, it was shown that the oral administration of natto and NK enhance the fibrinolytic activity in plasma was evaluated periodically. A shortening of ELT and an elevation of EFA were found for a long time (from 2 to 8 hr) after a single administration of natto (p<0.01). The enteric coated capsules of NK (2.13 CU/mg of protein, M. W. approx. 20 Kd) were prepared as previously described (Sumi et al., Thromb. Res. 20: 711, 1980). Capsules containing 1.3 g of NK each, were administered after meals 3 times a day and fibrinolytic parameters were measured. Although there was no significant difference of WBCLT between the values before and after administration of NK, EFA was gradually increased from the 1st day to 8th day after administration. EDP was statistically higher (p<0.001) on the 1st day of NK administration in comparison with pre-administration. The significant increase of TPA antigen (p<0.005) was also proved over the long term.

These results demonstrate that Natto and NK will be useful not only for the treatment of embolism but also for prevention of the disease, since they are safety and also can be mass-produced.