Nattokinase is known to have an antihypertensive effect (helps prevent high blood pressure).  Researchers from the Hiroshima International University in Japan, carried out experiments to see if the protease activity of nattokinase was responsible for this effect.

The researchers used three groups of spontaneously hypertensive rats (rats bread to develop high blood pressure) with one of three treatments.

1. Basic diet with nattokinase.
2. Basic diet with fragments of nattokinase (since it’s broken up, it has not enzyme activity).
3. Basic diet (this was the control group).

The results were interesting.

Group 1 that received the nattokinase showed a reduction in systolic & diastolic blood pressure as well as plasma fibrinogen (a protein that is converted into fibrin to help clotting) levels.

Group 2 that received the fragments of nattokinase showed reduced systolic & diastolic blood pressure but no effect on fibrinogen levels. There was a reduction in plasma angiotensin II levels (this hormone increases blood pressure) in the plasma though.

The control group did not show a reduction in blood pressure.

So, what does all this mean?

Nattokinase and its fragments probably lowered blood pressure in different ways with the complete nattokinase breaking up fibrinogen in the plasma, whereas the fragments seem to have helped lower angiotensin II levels.

Source:

Antihypertensive effects of continuous oral administration of nattokinase and its fragments in spontaneously hypertensive rats.

Fujita M, Ohnishi K, Takaoka S, Ogasawara K, Fukuyama R, Nakamuta H.

Biol Pharm Bull. 2011;34(11):1696-701.