Nattokinase is an enzyme extracted from natto, a traditional Japanese food made by fermenting soybeans with the bacterium Bacillus subtilis. Despite its name, it is not a kinase — it belongs to the serine protease family, a group of enzymes that break down proteins. The name reflects its discovery in natto, not its biochemical function, which can be a source of confusion.
This enzyme has drawn attention for its potent fibrinolytic activity, meaning it can dissolve fibrin, a protein involved in blood clot formation. Wikipedia notes that nattokinase was first identified by Sumi et al. in 1987 and exhibits roughly four times the fibrinolytic activity of plasmin, the body's own clot-dissolving enzyme. It is not found in other soy foods — only in natto, where the fermentation process creates it.
What Is Nattokinase?
Nattokinase is a serine protease, not a kinase, though the name suggests otherwise. Biochemically, it is nearly identical to subtilisin E (99.5% sequence match), a bacterial enzyme produced by Bacillus subtilis. The Memorial Sloan Kettering Cancer Center describes it as a fibrinolytic enzyme that can break down fibrin clots in laboratory settings.
Its origin in natto gives it a long dietary history in Japan, where the fermented soybean dish has been consumed for centuries. The enzyme is extracted and purified for supplement use, typically in capsule form. The Japan Nattokinase Administration (JNKA) distinguishes natural nattokinase from synthetic versions, considering the latter counterfeit. Despite its food origins, the isolated enzyme behaves differently from the whole food — a distinction that matters when evaluating safety data.
How Does Nattokinase Work?
In laboratory studies, nattokinase directly degrades fibrin, the mesh-like protein that holds blood clots together. It also shows an affinity for heparin (binding at roughly 250 nM), which may enhance its clot-targeting behavior. But these are in vitro observations — what happens in a test tube does not always translate to the human body.
The bigger question is whether nattokinase survives digestion when taken orally. A pilot pharmacokinetic study by Ero et al. (2013) detected the enzyme in blood after a single oral dose, but the findings are preliminary. The WebMD entry on nattokinase notes the lack of convincing data on its absorption and metabolism. Injected intravenously, the enzyme works differently than when swallowed — and the oral route remains uncertain. It would be a mistake to assume that in vitro potency translates directly to in vivo effects.
Potential Cardiovascular Benefits: What the Research Says
The evidence for nattokinase's heart-health effects is mixed, with some small studies showing promise and others delivering null results. A 2013 study by Jang et al. found that nattokinase supplementation improved blood flow and reduced blood pressure in prehypertensive participants compared to placebo. Chen et al. (2018, Biomarker Insights) reported additional cardiovascular-related findings, but the overall body of research remains limited.
The most rigorous trial to date, the 2021 atherothrombotic prevention study by Hodis et al., found no effect of long-term nattokinase supplementation on subclinical atherosclerosis progression. Carotid artery intima-media thickness — a marker of early arterial disease — did not differ between the nattokinase and placebo groups. That null result matters. One study also examined nattokinase's potential to reduce blood clot risk after long flights, but like many others in this field, it was small and exploratory. No study has shown that nattokinase prevents heart attacks or strokes. The research points in interesting directions, but it stops well short of proof.
Safety, Side Effects, and Drug Interactions
Nattokinase carries a meaningful bleeding risk, especially when combined with anticoagulant or antiplatelet drugs. The MSKCC monograph warns that taking nattokinase with aspirin, warfarin, or similar medications can increase the chance of serious bleeding events, including intracerebral hemorrhage. There is also a documented case of a person who substituted nattokinase for warfarin after heart valve surgery and required a repeat valve replacement — a stark reminder that supplements are not interchangeable with prescribed blood thinners.
Other risks exist. A case report describes vascular necrosis of the upper extremity after someone self-treated with nattokinase for Peyronie's disease. People allergic to natto — the Bac s 1 allergen is the culprit — may experience anaphylaxis. And there is a theoretical danger of dislodging an existing clot, which could cause a stroke or embolus. Before anyone considers nattokinase, a healthcare provider needs to weigh these risks against the potential benefits. The enzyme is generally recognized as safe as a food component in natto, but concentrated supplement forms introduce different concerns.
How to Take Nattokinase
No standard dosage exists for nattokinase supplements. Potency varies between brands, and the studies use different formulations and amounts. What works in a controlled trial may not match what is on a store shelf. A healthcare provider should determine appropriate use based on individual health status and medication profile.
General Guidelines for Supplement Use
Before starting a nattokinase regimen, check for potential interactions with blood thinners, anti-inflammatory drugs, and other medications. Discussing your full health history with a doctor is not a formality — it is how you avoid serious complications. Product quality can vary, and independent testing is not universal. If you and your provider decide to proceed, choose a reputable brand and watch for any unusual bruising or bleeding.
NATTOKINASE 18-IN-1 POTENT BLEND
A multi-ingredient formula like the NATTOKINASE 18-IN-1 POTENT BLEND contains nattokinase alongside other nutrients. It is important to note that this specific blend has not been evaluated in the studies cited earlier. The added ingredients introduce their own variables and potential interactions. Medical advice before use is especially important here — the combination of compounds makes the safety profile less predictable than nattokinase alone.