The objective of this study was to examine the effects of nattokinase supplementation on blood pressure in subjects with pre-hypertension or stage 1 hypertension. In a randomized, double-blind, placebo-controlled trial, 86 participants ranging from 20 to 80 years of age with an initial untreated systolic blood pressure (SBP) of 130 to 159 mmHg received nattokinase (2,000 FU/capsule) or a placebo capsule for 8 weeks. Seventy-three subjects completed the protocol. Compared with the control group, the net changes in SBP and diastolic blood pressure (DBP) were -5.55 mmHg (95% confidence interval [CI], -10.5 to -0.57 mmHg; p<0.05) and -2.84 mmHg (CI, -5.33 to -0.33 mmHg; p<0.05), respectively, after the 8-week intervention. The corresponding net change in renin activity was -1.17 ng/mL/h for the nattokinase group compared with the control group (p<0.05). In conclusion, nattokinase supplementation resulted in a reduction in SBP and DBP. These findings suggest that increased intake of nattokinase may play an important role in preventing and treating hypertension.
Comment: Nattokinase is a fibrinolytic enzyme found in natto (fermented soy beans). The results of this study indicate that nattokinase is an effective treatment for mild hypertension. While nattokinase treatment decreased plasma rennin activity to some extent, it had no effect on angiotensin-converting enzyme activity. Therefore the mechanism of action of nattokinase as an hypertensive agent is not clear. Although it is a fibrinolytic enzyme, nattokinase does not appear to cause abnormal bleeding. It is no known, however, whether it is safe to administer nattokinase to people taking anticoagulant or platelet inhibiting medications.
Kim JY, Gum SN, Paik JK, Lim HH, Kim KC, Effects of nattokinase on blood pressure: a randomized, controlled trial. Ogasawara K, Inoue K, Park S, Jang Y, Lee JH. Hypertens Res. 2008 Aug;31(8):1583-8. View Abstract
