Thrombolytic Effect of Nattokinase on a Chemically Induced Thrombosis Model in Rat

This is one of the foundational laboratory studies behind nattokinase’s reputation as a “natural clot-buster,” and it is worth knowing where that reputation comes from.

In a rat thrombosis model, nattokinase restored blood flow more effectively than the natural enzymes plasmin or elastase, with a dose-dependent effect and relatively little depletion of fibrinogen — suggesting clot dissolution without excessive bleeding tendency. It was an encouraging early demonstration of fibrinolytic activity.

But the gap between this and human benefit is vast. The study used a handful of rats and an artificial clotting model, and clot-dissolving activity in a rat artery says nothing about whether an oral supplement prevents heart attacks or strokes in people. The marketing claims for nattokinase rest heavily on early studies like this one, which the later randomized human trial (Hodis 2021) failed to confirm.

We rate the evidence limited. It is preliminary animal work — interesting for the enzyme’s basic pharmacology, but no basis for the cardiovascular claims often attached to nattokinase supplements.