Nattokinase
Nattokinase is a fibrinolytic enzyme derived from natto (fermented soybeans) that has demonstrated ability to break down fibrin and support healthy blood clotting. Evidence suggests modest cardiovascular benefits including improved circulation and mild blood pressure reduction, though caution is needed with anticoagulant medications.
Quick Verdict
Legitimate fibrinolytic activity with promising cardiovascular data, but must be used cautiously around blood-thinning medications.
Nattokinase has real enzymatic activity and may support cardiovascular health. However, do NOT combine with blood thinners without medical supervision. Best suited for those with cardiovascular concerns who are not on anticoagulant therapy.
At a Glance
Dose
2000-4000 FU (fibrinolytic units) per day, equivalent to approximately 100-200mg nattokinase
When to Take
Between meals on an empty stomach for optimal absorption
Best Form
Enteric-coated capsules to protect enzyme from stomach acid; NSK-SD
Evidence
43% avg
What It Is
Nattokinase is a serine protease enzyme produced by the bacterium Bacillus subtilis during the fermentation of soybeans into natto, a traditional Japanese food. Discovered by Dr. Hiroyuki Sumi in 1987, it was found to have potent fibrinolytic (clot-dissolving) activity. Unlike pharmaceutical thrombolytics that require IV administration, nattokinase is active orally and survives gastric digestion to enter the bloodstream. It is measured in fibrinolytic units (FU) rather than milligrams. Nattokinase has gained significant attention in cardiovascular health circles as a natural alternative to support healthy clotting, though it should not be considered a replacement for prescribed anticoagulants in high-risk patients.
How It Works
Nattokinase supports cardiovascular health through several mechanisms. Its primary action is direct fibrinolysis — it directly degrades fibrin, the structural protein in blood clots. Additionally, it enhances the body's own fibrinolytic system by increasing tissue plasminogen activator (tPA) activity and inactivating plasminogen activator inhibitor-1 (PAI-1). This dual action promotes healthy clot resolution. Nattokinase also reduces blood viscosity, which improves microcirculation. Some studies suggest it may lower blood pressure through ACE-inhibitory activity and improved vascular endothelial function. The combined effects on fibrinolysis, blood viscosity, and vascular function contribute to its cardiovascular profile, though the clinical significance for primary prevention remains under investigation.
Evidence by Goal
circulation
Some evidence for improved blood flow, reduced viscosity, and mild blood pressure reduction, particularly in pre-hypertensive populations.
cardiovascular
Moderate evidence for fibrinolytic activity and supporting healthy blood clotting parameters. Long-term cardiovascular outcome data is still lacking.
Dosage & Usage
Standard Dose
2000-4000 FU (fibrinolytic units) per day, equivalent to approximately 100-200mg nattokinase
Loading Protocol
No loading phase; fibrinolytic effects are detectable within hours of dosing
Timing
Between meals on an empty stomach for optimal absorption; evening dosing may align with overnight thrombotic risk
Best Form
Enteric-coated capsules to protect enzyme from stomach acid; NSK-SD (nattokinase with vitamin K2 removed) for those on warfarin
📅 What to Expect
Day 1-7
Fibrinolytic activity detectable in blood within hours of dosing.
Week 2-4
Blood viscosity and fibrinogen levels may decrease.
Week 4-8
Blood pressure may show modest reduction. Circulation improving.
Month 2+
Sustained fibrinolytic and cardiovascular benefits. Plaque regression possible long-term.
🎯 How to Know It's Working
Blood feels less viscous (subjective)
Circulation may feel improved
Blood pressure slightly lower
If not working: If no change after 8 weeks, ensure 2000+ FU per dose. Do NOT combine with blood thinners without medical supervision.
🏷️ Buying Guide
✓ Look For
- • 2000 FU (fibrinolytic units) per capsule
- • Enteric-coated for intestinal absorption
- • NSK-SD or Doctor's Best brand quality
✗ Avoid
- • Products without FU activity listed
- • Combining with blood thinners without medical advice
🥗 Get It From Food
🛡️ Safety Profile
Common Side Effects
- • mild GI discomfort
- • easy bruising (at higher doses)
⚠️ Contraindications
- 🚫 bleeding disorders
- 🚫 scheduled surgery (discontinue 2 weeks prior)
- 🚫 active bleeding
💊 Drug Interactions
- • warfarin and other anticoagulants (significantly increased bleeding risk)
- • antiplatelet drugs (aspirin, clopidogrel)
- • NSAIDs (additive bleeding risk)
🔴 Serious Risks
- • increased bleeding risk when combined with anticoagulants
- • potential cerebral hemorrhage in those on blood thinners (case reports)
Long-Term Safety
Studies up to 12 months show good safety in healthy populations. The primary concern is interaction with blood-thinning medications. Natto has been consumed safely in Japan for centuries, though concentrated supplements provide much higher enzyme activity than dietary natto.
👥 Who Benefits Most
Best For
- ✓ individuals concerned about cardiovascular health
- ✓ those with a family history of blood clots
- ✓ people with mildly elevated blood pressure
- ✓ frequent long-haul travelers (DVT prevention)
Less Effective For
- — those already on anticoagulant therapy (risky interaction)
- — individuals without cardiovascular risk factors
📚 Key Research
3 peer-reviewed studies supporting this supplement's effects.
Nattokinase: a promising alternative in prevention and treatment of cardiovascular diseases
Weng Y, Yao J, Sparks S, Wang KY · Food Science and Biotechnology (2017)
Comprehensive review confirming nattokinase's fibrinolytic, antithrombotic, and blood pressure-lowering activities with a favorable safety profile for cardiovascular support.
A single-arm pilot study of nattokinase in reducing progression of subclinical atherosclerosis
Kurosawa Y, Nirengi S, Homma T, et al. · Journal of Atherosclerosis and Thrombosis (2015)
Nattokinase supplementation was associated with reduced progression of atherosclerotic plaque and improved lipid profiles in a pilot study.
Nattokinase decreases plasma levels of fibrinogen, factor VII, and factor VIII in human subjects
Ren NN, Chen HJ, Li Y, et al. · Hypertension Research (2017)
Nattokinase supplementation significantly reduced fibrinogen and blood pressure in pre-hypertensive subjects compared to placebo over 8 weeks.
💰 Cost & Forms
Estimated Monthly Cost
$15-35
🔗 Related Evidence Reviews
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