The properties of Natto (better known in its nutraceutical form as nattokinase) closely resemble plasmin which is your body's own blood-enhancing enzyme. Consequently, Natto helps decrease blood thickness, increase oxygen flow throughout the body, and attack excess fibrin, the protein that sticks to blood vessel walls and impedes blood flow. In one study, the use of Natto seems to have caused an 11% decrease in blood pressure after just two weeks.