Effects of Natto Extract on Endothelial Injury in a Rat Model

This laboratory study explored whether natto extract protects the lining of blood vessels — the endothelium — from injury, and whether its benefits exceed those of purified nattokinase alone.

In cell cultures and a rat model, natto extract reduced cell death in damaged endothelium and limited the thickening of vessel walls, with stronger antioxidant effects than nattokinase by itself. The authors propose combined antioxidant and anti-apoptotic mechanisms, suggesting the whole extract contains protective components beyond the headline enzyme.

This is preclinical, mechanism-oriented work. Results in rat vessels and cultured cells often do not translate to humans, and the study tells us nothing about clinical outcomes — whether natto protects a person’s arteries or prevents any event.

We rate the evidence limited. It is reasonable bench science, but its relevance to human cardiovascular health is speculative; it belongs to the hypothesis-generating fringe of the nattokinase literature, not to the evidence on which decisions should rest.