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Cardiovascular

Nattokinase

Bacillus subtilis natto
Evidence Level
Moderate
2 Clinical Trials
5 Documented Benefits
3/5 Evidence Score

Nattokinase is a fibrinolytic enzyme produced by Bacillus subtilis natto fermentation of soybeans (the traditional Japanese food natto). Distinguished by ability to break down fibrin (blood clots) — the only oral enzyme with substantial human data on cardiovascular and circulation effects. Used for cardiovascular support, deep vein thrombosis prevention, and recently long-COVID/post-vaccination spike protein concerns. Standardized in fibrinolytic units (FU).

Studied Dose 100-400 mg/day standardized to 2,000-8,000 FU (fibrinolytic units); typically taken on empty stomach
Active Compound Nattokinase (subtilisin NK, serine protease)

Benefits

Fibrinolytic Activity

Nattokinase directly cleaves fibrin (the protein scaffold of blood clots) — distinct from anticoagulants (which prevent clot formation by inhibiting clotting factors) and antiplatelets (which prevent platelet aggregation). Activates endogenous tissue plasminogen activator (tPA) and degrades fibrin directly.

Supported by Trial 1

Blood Pressure Modest Reduction

Kim 2008 and RCTs showed nattokinase (2,000 FU/day) modestly reduced both systolic and diastolic blood pressure in pre/hypertensive adults vs placebo. Effect size ~5-6 mmHg systolic — clinically meaningful but modest.

Supported by Trial 1

Cardiovascular Risk Markers

Several trials show nattokinase reduces fibrinogen, factor VII, and factor VIII levels — plus may reduce LDL and triglycerides, raise HDL. Multi-mechanism cardiovascular support.

Supported by Trial 1, Trial 2

Deep Vein Thrombosis (DVT) Prevention (Theoretical)

trial showed nattokinase (2 capsules/day) reduced edema and DVT incidence vs placebo on long-haul flights. Mechanism plausible; sample size limited. Standard DVT prevention for high-risk patients remains anticoagulants and compression.

Supported by Trial 2

Long-COVID / Spike Protein Research (Emerging)

Recent in vitro research suggests nattokinase may degrade SARS-CoV-2 spike protein. Generated significant interest in long-COVID and post-vaccine spike protein clearance. CRITICAL CAVEAT: in vitro evidence; human clinical translation not established; do NOT use as substitute for evidence-based COVID treatments.

Supported by Trial 1, Trial 2

Mechanism of action

1

Direct Fibrin Cleavage

Nattokinase is a serine protease that directly cleaves fibrin into smaller fragments — same end result as endogenous plasmin. Distinct from anticoagulant drugs (which work upstream by inhibiting clotting factors).

2

tPA Activation

Nattokinase enhances production and activity of endogenous tissue plasminogen activator (tPA) — increasing physiological fibrinolytic capacity. Both direct (NK cleaves fibrin) and indirect (NK activates plasmin via tPA) mechanisms.

3

PAI-1 Inhibition

Nattokinase reduces plasminogen activator inhibitor-1 (PAI-1) — a fibrinolysis inhibitor. Lower PAI-1 = greater fibrinolytic activity. PAI-1 elevation associated with metabolic syndrome and CV risk.

4

Pleiotropic Cardiovascular Effects

Beyond fibrinolysis: BP reduction (mechanism unclear; possibly via ACE inhibition), modest lipid effects, reduced platelet aggregation. Multi-mechanism CV agent.

Clinical trials

1
Nattokinase for Hypertension — Kim 2008
PubMed

Double-blind RCT of nattokinase (2,000 FU/day) vs placebo in 86 prehypertensive adults for 8 weeks.

86 prehypertensive adults.

Nattokinase reduced systolic BP by ~5.5 mmHg and diastolic BP by ~2.8 mmHg vs placebo. Modest but clinically meaningful effect. Subsequent Jensen 2016 trial confirmed similar magnitude.

2
Nattokinase for DVT Prevention (Long-Flight) — Cesarone 2003
PubMed

RCT of nattokinase + pycnogenol vs placebo for DVT prevention in 200 long-haul flight passengers.

200 high-risk flight passengers.

Nattokinase + pycnogenol group: 0% DVT incidence vs 5% in placebo group; significant edema reduction. Combined product limits attribution to nattokinase alone. Suggestive but not definitive.

Side effects and drug interactions

Common Potential side effects

BLEEDING RISK — fibrinolytic activity carries theoretical bleeding risk; particular concern with anticoagulants/antiplatelets, recent surgery, GI ulcers, intracranial bleeding history.
GI distress at high doses.
Headache.
Allergic reactions (rare; soybean source).
Skin reactions rare.
PRE-SURGERY DISCONTINUATION — discontinue 1-2 weeks before any surgery to reduce bleeding risk.

Important Drug interactions

ANTICOAGULANTS (warfarin, apixaban, rivaroxaban, dabigatran, edoxaban, heparin) — additive bleeding risk; CONSULT prescriber; INR monitoring with warfarin essential; avoid concurrent without medical supervision.
ANTIPLATELET drugs (aspirin, clopidogrel, prasugrel, ticagrelor) — additive bleeding risk; consult cardiologist.
Fibrinolytic drugs (tPA, alteplase, streptokinase) — additive; not relevant for chronic outpatient use.
NSAIDs — additive bleeding risk especially with chronic use.
Fish oil, garlic, ginkgo, vitamin E (high-dose) — multiple supplements have antiplatelet effects; cumulative bleeding risk.
Soybean allergy — nattokinase is derived from fermented soy; theoretical cross-reactivity (typically very low residual soy protein in standardized products).

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Frequently asked questions about Nattokinase

What is Nattokinase?

Nattokinase is a fibrinolytic enzyme produced by Bacillus subtilis natto fermentation of soybeans (the traditional Japanese food natto).

What does Nattokinase do?

Nattokinase is a serine protease that directly cleaves fibrin into smaller fragments — same end result as endogenous plasmin. Distinct from anticoagulant drugs (which work upstream by inhibiting clotting factors). In clinical research, Nattokinase has been studied for fibrinolytic activity, blood pressure modest reduction, cardiovascular risk markers.

Who should take Nattokinase?

Nattokinase may be most relevant for people interested in cardiovascular. It has been clinically studied for fibrinolytic activity, blood pressure modest reduction, cardiovascular risk markers. As with any supplement, consult your healthcare provider before starting, especially if you have medical conditions or take prescription medications.

How long does Nattokinase take to work?

Most clinical trial effects appear over weeks of consistent use; individual response varies. Acute or same-day effects (where applicable) typically appear within hours, but most cumulative benefits — particularly those affecting biomarkers, mood, sleep quality, or chronic symptoms — require 4-12 weeks of regular use to fully assess. If you don't notice benefit after 12 weeks at the appropriate dose, it may not be your responder.

When is the best time to take Nattokinase?

For cardiovascular or metabolic goals, Nattokinase is typically taken with meals to support absorption and reduce GI sensitivity. Effects on biomarkers (cholesterol, blood pressure, blood sugar) build over 8-12+ weeks of consistent daily use. Always check product labeling and follow personalized guidance from your healthcare provider.

Is Nattokinase worth taking?

Nattokinase has moderate clinical evidence (Evidence Level 3/5 on NutraSmarts) — meaningful trial support exists, though results are less consistent than top-tier ingredients. Whether it's worth taking depends on your specific goals, what you've already tried, your budget, and your overall supplement strategy. The honest framing: no supplement is essential for most people, and lifestyle factors (sleep, exercise, diet, stress management) typically produce larger effects than any single supplement. Nattokinase is most worth trying if its evidence-supported uses align with your specific goals.

What is the recommended dosage of Nattokinase?

The clinically studied dose for Nattokinase is 100-400 mg/day standardized to 2,000-8,000 FU (fibrinolytic units); typically taken on empty stomach. Always follow product labeling and consult a healthcare provider for personalized dosing recommendations.

What is Nattokinase used for?

Nattokinase is studied for fibrinolytic activity, blood pressure modest reduction, cardiovascular risk markers. Nattokinase directly cleaves fibrin (the protein scaffold of blood clots) — distinct from anticoagulants (which prevent clot formation by inhibiting clotting factors) and antiplatelets (which prevent platelet aggregation).