Abstract
The production of vitamin K by Bacillus natto and the plasma vitamin K concentration of subjects after ingesting natto were studied. In contrast to no change in the phylloquinon (vitamin K1) and menaquinone-4 (MK-4) concentrations, a strong increase in menaquinone-7 (MK-7) was apparent during natto fermentation. The highest content of 1, 750μg of MK-7/100g wet. wt. was found in the Miyagino strain when incubated for 48 h at 37°C. The plasma MK-7 concentration of the subjects was dose-dependent, with a maximum value of 57.1±7.7ng/ml. The effect of natto ingestion on the plasma concentration of MK-7 continued for a long time : 48 h after ingesting 100 g of natto, it was 9 times higher than the control value. Under these conditions, there was no effect on the blood coagulation or fibrinolytic system of the subjects.
