The fermented soybean product natto is a popular traditional food in Japan and is considered a health supplement. To investigate the effect of supplements derived from natto on blood pressure in patients with lifestyle diseases, a cross-over, double-blind study was performed. The substances used were fermented soya (natto) extract and NKCP®, with main components of subtilisin NAT and bacillopeptidase F, respectively. A four-week course of NKCP® significantly decreased average systolic blood pressure from 130.9 to 120.5 mmHg (p=0.001) and diastolic blood pressure from 72.9 to 68.6 mmHg (p=0.024).
However, after a four-week treatment with fermented soya (natto) extract, no significant changes in systolic or diastolic blood pressure were found (126.8 to 126.4 mmHg, and 70.9 to 68.3 mmHg, respectively). The difference in the effect on blood pressure between these two substances is considered as owing to the differences of the in vitro experimental results on blood fluidity.
The use of dietary supplements, especially NKCP®, from natto provides additional blood pressure lowering effects in patients already receiving medical care.