Nattokinase and Cardiovascular Health: Useful Enzyme or “Natural Blood Thinner” Hype?
Nattokinase occupies an interesting place in cardiovascular nutrition. Unlike many supplements promoted for circulation, it has a plausible biological mechanism, measurable fibrinolytic activity and a growing body of human research. There are reasonable scientific grounds for being interested in it.
The difficulty begins when nattokinase is described simply as a “natural blood thinner” or promoted as something that dissolves arterial plaque, cleans arteries or replaces anticoagulant medication. Those claims extend well beyond what clinical trials have established.
The One-Minute Read
Nattokinase is an enzyme produced during fermentation of natto, the traditional Japanese fermented soybean food. Its cardiovascular interest comes largely from its effects on fibrin and the body's fibrinolytic system, which participates in breaking down blood clots.
Human studies suggest nattokinase may influence blood pressure and several coagulation or fibrinolysis pathways. Some studies have also reported favorable changes in carotid artery measurements, although those findings have not been consistent. In one of the strongest longer-term randomized trials, 2,000 fibrinolytic units (FU) daily did not slow progression of carotid atherosclerosis over approximately three years.
Nattokinase nevertheless remains an interesting nutritional adjunct. What has not been established is that it prevents heart attacks or strokes, reverses atherosclerosis, or provides protection equivalent to anticoagulant or antiplatelet medications.
Because nattokinase affects fibrinolysis, anyone taking medications that alter clotting, anyone with a bleeding disorder, or anyone preparing for surgery should discuss its use with a healthcare professional.
What Is Nattokinase?
Nattokinase is a serine protease produced when soybeans are fermented with Bacillus subtilis to make natto. It was isolated in the 1980s after researchers observed that extracts from natto could break down fibrin, the protein mesh that helps stabilize a blood clot.
That fibrinolytic activity is the basis for much of the cardiovascular interest in nattokinase. Laboratory and mechanistic studies have examined direct effects on fibrin as well as possible changes in endogenous fibrinolytic pathways, platelet activity, blood pressure, inflammation and vascular biology.
The biology is credible. What remains less certain is how much those effects change clinically important outcomes such as progression of atherosclerosis, myocardial infarction or stroke.
Why “Natural Blood Thinner” Is an Imperfect Description
“Blood thinner” is a familiar phrase, but medically it is imprecise. Blood does not literally become thinner when someone takes aspirin, warfarin, apixaban or another antithrombotic treatment. These medications act on different parts of the coagulation or platelet systems.
Nattokinase is better known for its fibrinolytic activity. Fibrinolysis is the process through which the body breaks down fibrin. That is different from the mechanism of an anticoagulant such as warfarin or apixaban and different again from the antiplatelet activity of aspirin or clopidogrel.
The phrase “natural blood thinner” can therefore imply an equivalence that has never been demonstrated. Nattokinase has biological activity relevant to clotting and fibrin metabolism, but it should not be assumed to provide the same protection as medications tested for specific cardiovascular indications.
What Does FU Mean?
Nattokinase supplements are commonly labeled in fibrinolytic units, or FU, rather than simply milligrams. FU describes measured enzymatic activity. For an enzyme such as nattokinase, this can be more informative than ingredient weight alone because preparations containing the same milligram amount may not necessarily provide identical activity.
A common supplemental amount is 2,000 FU per day, although products and clinical studies have used larger amounts. Studies have evaluated doses around 6,000 FU per day, and other formulations provide 4,000 FU or more.
There is no established optimal cardiovascular dose comparable to the dosing standards available for approved cardiovascular medications. A larger FU number should not automatically be interpreted as greater clinical benefit.
What Have Human Studies Found?
The clinical literature is mixed, which is one reason nattokinase is better discussed with some nuance.
One of the most informative studies was a double-blind randomized trial involving 265 adults without established clinical cardiovascular disease. Participants received either 2,000 FU of nattokinase daily or placebo and were followed for approximately three years. Researchers repeatedly measured carotid intima-media thickness, arterial stiffness, blood pressure and numerous metabolic, inflammatory, coagulation and fibrinolysis markers.
Nattokinase did not significantly slow progression of carotid atherosclerosis or arterial stiffness compared with placebo. The investigators also did not find meaningful improvements across the cardiovascular biomarkers they measured. The duration of this trial makes it particularly useful when considering claims about long-term vascular effects. [Study]
Other research has produced more encouraging findings. A randomized study using approximately 6,000 FU per day reported reductions in carotid intima-media thickness and carotid plaque size over 26 weeks. The findings are interesting and deserve further study, but a single relatively small trial does not establish that nattokinase removes atherosclerotic plaque. [Study]
A systematic review and meta-analysis of six randomized controlled trials involving 546 participants found modest reductions in systolic and diastolic blood pressure. The same analysis did not establish a consistent lipid-lowering benefit and noted that additional research is needed to clarify the influence of dose and treatment duration. [Systematic review and meta-analysis]
Scientific reviews continue to describe potentially useful fibrinolytic, antithrombotic and vascular mechanisms while reaching a similar conclusion: larger and better clinical trials are still needed before nattokinase can be assigned the same preventive role as therapies supported by cardiovascular-outcome trials. [Review]
Does Nattokinase Remove Arterial Plaque?
Atherosclerotic plaque is biologically complex. Depending on its stage and location, plaque may contain cholesterol, inflammatory cells, connective tissue, calcium, necrotic material and other components embedded within the arterial wall. It is not simply a blood clot sitting inside an artery waiting to be dissolved.
For that reason, fibrinolytic activity should not be translated into a claim that nattokinase “dissolves plaque.” Some clinical studies have reported favorable changes in carotid measurements, and those findings warrant continued investigation. Current evidence is not sufficient to conclude that nattokinase reverses coronary or carotid atherosclerosis.
What About Blood Pressure?
Blood pressure is one of the more interesting areas of nattokinase research. The randomized-trial meta-analysis found an average reduction of approximately 3.5 mmHg in systolic blood pressure and just over 2 mmHg in diastolic blood pressure compared with placebo. [Systematic review and meta-analysis]
Those are modest changes and do not make nattokinase a substitute for appropriate treatment of hypertension. They do suggest that the cardiovascular effects being studied may extend beyond fibrinolysis alone.
Where Nattokinase May Fit in Preventive Cardiology
Nattokinase is best viewed as a possible adjunct rather than the foundation of a cardiovascular prevention program.
Preventive cardiology begins with understanding the patient's actual risk. Blood pressure, ApoB-containing lipoproteins, lipoprotein(a), glucose metabolism, diabetes, smoking, family history, exercise, body composition and the presence or absence of atherosclerosis carry considerably more clinical weight than the choice of any individual supplement.
When atherosclerosis is already present, treatment should be directed at the processes known to drive plaque progression and cardiovascular events. Nutrition and carefully selected supplements can be part of that strategy, but they should not displace treatments with established outcome data when those treatments are medically indicated.
Nattokinase still may have a role within that larger approach. The available science is substantial enough that it should not be dismissed simply because it is sold as a supplement. The same evidence also argues against promoting it as something it has not been proven to be.
Nattokinase Is Not a Substitute for Anticoagulation
Patients with atrial fibrillation, venous thromboembolism, mechanical heart valves or other medical indications for anticoagulation should not assume that nattokinase provides equivalent protection.
A published case report described a patient with a mechanical aortic valve who stopped warfarin and substituted nattokinase. The patient subsequently developed thrombosis of the mechanical valve and required repeat valve replacement surgery. A single case report cannot determine the overall effectiveness or safety of a therapy, but it illustrates why nattokinase should not be treated as a replacement for therapeutic anticoagulation. [Case report]
Bleeding and Medication Considerations
The same biological activity that makes nattokinase interesting also means it should not be treated as an inert nutritional ingredient.
Additional care is appropriate when nattokinase is used with medications that alter coagulation or platelet activity. These may include warfarin, apixaban, rivaroxaban, dabigatran, heparin, clopidogrel and aspirin, depending on the patient's circumstances. Reviews of cardiovascular supplements identify bleeding and drug interactions as considerations when nattokinase is used. [Review]
People with bleeding disorders or a history of significant bleeding should also discuss nattokinase with their healthcare professional. The same consideration applies before surgery, dental procedures or other invasive procedures.
That does not mean nattokinase routinely causes dangerous bleeding. Clinical studies have generally reported reasonable tolerability, and observational data in patients with vascular disease have also provided some reassurance. [Study] It does mean that a biologically active fibrinolytic enzyme belongs on the medication and supplement list when clinical decisions involving bleeding or clotting are being made.
The HormoneSynergy® Perspective
Nattokinase illustrates why cardiovascular supplements are best evaluated somewhere between enthusiasm and dismissal.
There is a real enzyme, a credible biological mechanism and human clinical research. There are also unanswered questions about dose, long-term effectiveness, patient selection and whether the physiological effects reported in studies ultimately translate into fewer cardiovascular events.
For selected patients, nattokinase may be reasonable to consider within a broader cardiovascular strategy. Formulations providing 2,000 FU, 4,000 FU and higher amounts are available, and clinical studies have investigated several different dosing ranges. A 4,000-FU formulation provides a meaningful amount of measured fibrinolytic activity, but that should not be interpreted to mean that 4,000 FU has been established as the optimal cardiovascular dose or is necessarily more clinically effective than 2,000 FU.
What matters is the context in which nattokinase is being used. It should not distract from atherosclerotic burden, ApoB, lipoprotein(a), blood pressure, glucose metabolism, smoking, exercise, body composition, diet or appropriate medical treatment when cardiovascular disease is present.
Nattokinase may prove to have a useful supporting role. The current evidence does not justify asking it to carry the weight of an entire cardiovascular prevention program.
Nattokinase Options Available Through HormoneSynergy®
For people who choose to include nattokinase as part of a broader cardiovascular or longevity strategy, HormoneSynergy® offers both a standalone nattokinase formula and a combination proteolytic-enzyme formula. These products are intended for nutritional support and should not be considered substitutes for medically indicated anticoagulant, antiplatelet, lipid-lowering or blood-pressure therapy.
XYMOGEN® Nattokinase 120 Capsules
Each capsule provides 2,000 FU of nattokinase, an enzyme originally identified in natto, the traditional Japanese fermented soybean food. This standalone formulation may be considered when the goal is nutritional support for healthy circulation and normal fibrin metabolism.*
RetzlerRx® Nattozymes® & Serrazimes®
This broader enzyme formula combines nattokinase-derived Nattozymes® with Serrazimes®, a proteolytic enzyme. The combination is formulated to support healthy fibrin metabolism, circulation and normal protein-breakdown processes.* It may be considered when a broader proteolytic-enzyme formula is desired rather than standalone nattokinase.
View RetzlerRx® Nattozymes® & Serrazimes®
Important: Nattokinase and other fibrinolytic or proteolytic enzymes may affect pathways involved in clotting and fibrin breakdown. Discuss their use with your healthcare professional if you take anticoagulant or antiplatelet medication, have a bleeding disorder, or are preparing for surgery or another invasive procedure.
*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.
Medicine, Not Marketing.
A supplement does not become ineffective because it is natural, nor does a plausible mechanism establish that it prevents disease. The useful questions are what the evidence actually shows, whether the intervention makes sense for the individual patient, and where it belongs within the larger cardiovascular picture.
Frequently Asked Questions
Is nattokinase a blood thinner?
Nattokinase has fibrinolytic activity, meaning it can influence the breakdown of fibrin. “Blood thinner” is an imprecise shorthand because nattokinase does not act in the same way as prescription anticoagulants or antiplatelet medications.
Does nattokinase dissolve arterial plaque?
There is not sufficient evidence to conclude that nattokinase dissolves atherosclerotic plaque. Some clinical studies have reported favorable changes in carotid artery measurements, while longer-term randomized research has not demonstrated reduced progression of carotid atherosclerosis.
What does FU mean on a nattokinase supplement?
FU stands for fibrinolytic units and reflects the measured enzymatic activity of nattokinase. Products may provide different amounts of FU per serving, but an optimal dose for cardiovascular prevention has not been established.
Can nattokinase replace aspirin or an anticoagulant?
No. Nattokinase has not been shown to provide protection equivalent to medically indicated anticoagulant or antiplatelet therapy. Patients should not substitute nattokinase for these medications without guidance from the clinician managing their cardiovascular care.
Can nattokinase be taken with blood thinners?
Because nattokinase affects fibrinolysis, combining it with anticoagulant or antiplatelet medications may increase concern about bleeding. Anyone taking medications that affect coagulation or platelet function should discuss nattokinase with a healthcare professional before using it.
This article is for educational purposes and is not a substitute for individualized medical advice, diagnosis or treatment.
This article is part of the HormoneSynergy® Longevity Medicine education series covering preventive cardiology, metabolic health, hormone optimization, body composition, and advanced diagnostics for healthy aging.
Return to the Longevity Medicine Guide →