Nattokinase: Benefits, Dosage, Safety, and What the Research Actually Shows

Nattokinase has become one of the most talked-about cardiovascular supplements in recent years — and for good reason. Decades of research suggest this enzyme, derived from a traditional Japanese food, may support healthy blood pressure, promote natural clot dissolution, and improve circulation. But separating verified science from marketing hype requires a careful look at the actual studies.

This guide breaks down every major nattokinase research finding, explains exactly how it works in the body, and gives you clear guidance on dosage, safety, and supplement selection.

What Is Nattokinase?

Nattokinase is a fibrinolytic (clot-dissolving) enzyme extracted from natto, a traditional Japanese fermented soybean food that has been consumed for over 1,000 years.

The enzyme was first identified and characterized in 1987 by Dr. Hiroyuki Sumi, a researcher at the University of Chicago Medical School. While studying various natural compounds for their ability to dissolve blood clots, Dr. Sumi placed natto on artificial thrombi (blood clots) in petri dishes and observed that the natto completely dissolved the clots within 18 hours — a remarkably potent fibrinolytic effect that rivaled pharmaceutical agents.

The Science Behind the Enzyme

Nattokinase is a serine protease enzyme produced by the bacterium Bacillus subtilis var. natto during the fermentation of soybeans. It consists of 275 amino acid residues with a molecular weight of approximately 27.7 kDa. Unlike many dietary enzymes that are destroyed during digestion, research has demonstrated that nattokinase can survive gastrointestinal transit and enter the bloodstream in an active form.

Technically classified as subtilisin NAT (EC 3.4.21.62), nattokinase belongs to the subtilisin family of serine proteases. Its enzymatic activity is measured in Fibrinolytic Units (FU), which quantify the enzyme's ability to break down fibrin — the protein that forms the structural framework of blood clots.

Key Takeaway: Nattokinase is not a synthetic drug — it is a naturally occurring enzyme from a fermented food with a long history of traditional consumption. Its fibrinolytic activity was scientifically validated in the late 1980s and has been studied in dozens of clinical trials since.

How Nattokinase Works: The Fibrinolytic Mechanism

Nattokinase works through multiple simultaneous pathways to break down fibrin, the protein mesh that holds blood clots together, while also enhancing the body's own natural clot-dissolving system.

Understanding how nattokinase operates requires a brief look at how the body normally manages blood clots.

The Body's Clotting and Anti-Clotting Balance

Your body maintains a constant balance between coagulation (clot formation) and fibrinolysis (clot dissolution). When this balance tips too far toward coagulation, excessive clotting can restrict blood flow, contributing to cardiovascular events.

The body's primary clot-dissolving agent is plasmin, which is generated from its inactive precursor plasminogen by an enzyme called tissue plasminogen activator (t-PA). Nattokinase influences this system at multiple levels:

1. Direct fibrinolysis — Nattokinase directly cleaves and degrades fibrin, dissolving existing clots without requiring intermediate activation steps (Fujita et al., Biological & Pharmaceutical Bulletin, 1995).
2. Increased t-PA production — Nattokinase stimulates vascular endothelial cells to produce more t-PA, amplifying the body's own clot-dissolving capacity (Urano et al., Life Sciences, 2001).
3. Plasminogen activator inhibitor-1 (PAI-1) reduction — Nattokinase decreases levels of PAI-1, a protein that suppresses fibrinolysis. Lower PAI-1 means the body's clot-dissolving machinery works more efficiently (Hsia et al., Nutrition Research, 2009).
4. Factor VIII reduction — Some evidence suggests nattokinase may reduce coagulation Factor VIII, further shifting the balance toward anti-coagulation (Kurosawa et al., Pathophysiology of Haemostasis and Thrombosis, 2002).

Nattokinase vs. Pharmaceutical Anticoagulants

Key Takeaway: Nattokinase is unique among cardiovascular supplements because it both directly dissolves fibrin AND enhances the body's own fibrinolytic system. Pharmaceutical blood thinners primarily prevent new clots from forming — nattokinase actively degrades existing fibrin.

Nattokinase Benefits: What the Research Shows

1. Cardiovascular Health and Blood Pressure Reduction

Multiple clinical trials have demonstrated that nattokinase supplementation can reduce both systolic and diastolic blood pressure in adults with pre-hypertension or mild hypertension.

The most frequently cited blood pressure study is a randomized, double-blind, placebo-controlled trial by Kim et al. published in Hypertension Research (2008). In this study, 86 participants with initial systolic blood pressure between 130-159 mmHg were randomized to receive either nattokinase (2,000 FU daily) or placebo for 8 weeks. The nattokinase group experienced:

• A mean reduction of 5.55 mmHg in systolic blood pressure
• A mean reduction of 2.84 mmHg in diastolic blood pressure
• A significant decrease in plasma renin activity

A subsequent study by Jensen et al., published in Integrated Blood Pressure Control (2016), examined nattokinase supplementation in 79 North American subjects with pre-hypertension and Stage 1 hypertension. After 8 weeks of supplementation with 2,000 FU daily, significant reductions in both systolic and diastolic blood pressure were observed, with effects more pronounced in male participants.

Fujita et al. (2011), publishing in Nutrition Research, conducted a trial with 73 volunteers receiving nattokinase at varying doses and reported dose-dependent blood pressure improvements in hypertensive subjects.

2. Fibrinolysis and Blood Clot Dissolution

Nattokinase has been shown in both laboratory and human studies to enhance fibrinolytic activity and reduce markers associated with excessive clotting.

The foundational research by Sumi et al. (Experientia, 1987) demonstrated nattokinase's potent ability to dissolve fibrin clots in vitro. Since then, human studies have confirmed these effects:

• Hsia et al. (Nutrition Research, 2009) conducted a randomized, double-blind, placebo-controlled crossover study in 12 healthy male subjects. A single dose of nattokinase (2,000 FU) significantly enhanced fibrinolytic activity, increased levels of D-dimer (a marker of clot breakdown), and reduced both fibrinogen and Factor VII levels within 8 hours.
• Ren et al. (Acta Haematologica, 2006) studied the effects of nattokinase in a randomized crossover trial and found that oral nattokinase significantly increased fibrinolytic activity in plasma, with peak effects occurring 4-8 hours after ingestion.
• Kurosawa et al. (Pathophysiology of Haemostasis and Thrombosis, 2002) demonstrated that nattokinase reduced Factor VII, Factor VIII, and fibrinogen levels in a study of cardiovascular patients, suggesting comprehensive anti-coagulant effects beyond simple fibrin degradation.

3. Cholesterol and Lipid Management

Clinical evidence indicates that nattokinase supplementation may improve lipid profiles by reducing total cholesterol and triglycerides while raising beneficial HDL cholesterol.

Kim et al. (Journal of Atherosclerosis and Thrombosis, 2008) investigated the lipid-modifying effects of nattokinase in a randomized, placebo-controlled trial. Participants receiving nattokinase for 8 weeks showed:

• Reduction in total cholesterol
• Decrease in LDL cholesterol
• Decrease in triglycerides
• Favorable changes in HDL-to-LDL ratio

A systematic review and meta-analysis by Chen et al. (Complementary Therapies in Medicine, 2022) pooled data from multiple clinical trials and confirmed that nattokinase supplementation was associated with statistically significant improvements in total cholesterol and triglyceride levels.

4. Circulation Improvement

Research suggests that nattokinase may reduce blood viscosity and improve microcirculation, which can benefit overall cardiovascular function.

Pais et al. (Clinical Hemorheology and Microcirculation, 2006) studied the effects of nattokinase on blood viscosity in a group of patients. They found that nattokinase supplementation reduced whole blood viscosity across both high and low shear rates, suggesting improved blood flow characteristics.

The reduction in fibrinogen levels — a key determinant of blood viscosity — appears to be one mechanism through which nattokinase improves circulation. Lower fibrinogen means less "sticky" blood, which flows more easily through capillaries and small vessels.

5. Potential Neuroprotective Effects

Emerging preclinical research suggests nattokinase may have neuroprotective properties, including the ability to degrade amyloid fibrils, though human evidence remains limited.

A notable laboratory study by Hsu et al. (Journal of Agricultural and Food Chemistry, 2009) demonstrated that nattokinase could degrade amyloid fibrils — the abnormal protein deposits associated with Alzheimer's disease and other neurodegenerative conditions. The enzyme degraded these fibrils in a dose-dependent manner in vitro.

Additionally, Ahn et al. (Stroke, 2015, animal model) showed that nattokinase administration in a rat model of ischemic stroke reduced infarct size and improved neurological outcomes.

While these findings are promising, it is important to emphasize that neuroprotective applications remain in the early research stage. No large-scale human clinical trials have yet confirmed these effects.

Summary of Nattokinase Benefits by Evidence Strength

Key Takeaway: The strongest evidence for nattokinase centers on blood pressure reduction and enhanced fibrinolysis, supported by multiple randomized controlled trials. Lipid and circulation benefits have solid but less extensive support. Neuroprotective effects are intriguing but still in early research phases.

Nattokinase Dosage: How Much Should You Take?

The most commonly studied and recommended nattokinase dose is 2,000 FU (100 mg) per day for general cardiovascular support, though doses up to 8,000 FU have been used safely in studies and may offer enhanced benefits for specific goals.

Understanding Fibrinolytic Units (FU)

Nattokinase potency is measured in Fibrinolytic Units (FU), not milligrams. This is critical because the enzymatic activity — how effectively the supplement dissolves fibrin — matters far more than the raw weight of the powder. Two supplements can contain the same weight in milligrams but deliver vastly different FU counts depending on enzyme concentration and purity.

The Japan Nattokinase Association (JNKA) standardized the FU measurement system. One FU represents the amount of nattokinase required to generate a defined amount of fibrin degradation products under standardized laboratory conditions.

Dosage Guidelines by Goal

Timing and Administration

Research does not provide a definitive consensus on optimal timing, but several practical patterns have emerged:

• Empty stomach preferred — Taking nattokinase between meals (or at least 30 minutes before eating) may improve absorption, as food can partially inhibit enzyme activity.
• Evening dosing — Some practitioners recommend evening intake because fibrinolytic activity naturally decreases at night, and blood clot risk is statistically higher in the early morning hours. Taking nattokinase in the evening may help maintain fibrinolytic activity during this higher-risk window.
• Consistent daily use — Fibrinolytic benefits build with consistent supplementation. The clinical trials showing significant results used daily dosing for 4-8 weeks minimum.
• Split dosing at higher amounts — If taking 4,000 FU or more, splitting into two daily doses (morning and evening) may provide more sustained enzyme activity throughout the day.

Key Takeaway: Start with 2,000 FU daily for general cardiovascular support. Higher doses up to 8,000 FU may be appropriate for specific goals, but always discuss with your healthcare provider before exceeding standard doses, especially if you take any medications.

Nattokinase vs. Other Blood Health Supplements

Nattokinase is the most extensively studied fibrinolytic enzyme supplement, but it is often compared to lumbrokinase, serrapeptase, and aspirin — each of which works through a different mechanism.

Head-to-Head Considerations

• Nattokinase vs. lumbrokinase: Both are fibrinolytic enzymes, but nattokinase has substantially more published clinical trial data. Lumbrokinase may have a faster onset in some applications, but its standardization is less consistent across brands.
• Nattokinase vs. serrapeptase: Serrapeptase is primarily an anti-inflammatory enzyme with mild fibrinolytic properties. For individuals seeking clot dissolution and blood pressure support, nattokinase has far stronger evidence. Serrapeptase may be more appropriate when inflammation is the primary concern.
• Nattokinase vs. aspirin: These work through completely different mechanisms. Aspirin inhibits platelet aggregation (preventing clumps), while nattokinase dissolves fibrin (breaking down clot structure). They are not interchangeable. Some integrative practitioners use both, but this requires medical supervision due to increased bleeding risk.

Key Takeaway: If your primary goal is supporting healthy fibrinolysis and blood pressure, nattokinase has the strongest evidence base among enzyme-based supplements. It is not a replacement for prescribed anticoagulants or antiplatelet therapy — always consult your physician.

Safety, Side Effects, and Drug Interactions

Nattokinase is generally well-tolerated in healthy adults at doses up to 8,000 FU per day, but it carries important safety considerations for people on blood-thinning medications, those scheduled for surgery, and pregnant or nursing women.

Safety Profile

Multiple clinical trials have reported no serious adverse events associated with nattokinase supplementation at standard doses. The Japan Nattokinase Association (JNKA) has reviewed the safety data extensively and considers nattokinase safe for healthy adults when taken as directed.

A safety study by Ero et al. (Functional Foods in Health and Disease, 2013) evaluated the safety and tolerability of nattokinase in healthy volunteers and found no clinically significant adverse effects across hematological, hepatic, or renal parameters.

Potential Side Effects

Reported side effects are uncommon and generally mild:

• Occasional gastrointestinal discomfort (nausea, diarrhea)
• Bruising more easily (at higher doses)
• Rare cases of epistaxis (nosebleed)

Critical Drug Interactions and Warnings

The Vitamin K2 Consideration

Traditional natto contains significant amounts of vitamin K2 (menaquinone-7), which actually promotes coagulation — the opposite of nattokinase's fibrinolytic effect. Many nattokinase supplements are deliberately processed to remove vitamin K2, making them safe for people on warfarin. However, some formulas intentionally include vitamin K2 for its bone and cardiovascular benefits (such as reducing arterial calcification). If you take warfarin, always verify that your nattokinase supplement is vitamin K2-free.

Key Takeaway: Nattokinase has a strong safety record in healthy adults. The most critical precaution is for anyone taking prescription blood thinners — never combine nattokinase with anticoagulant or antiplatelet medications without direct physician oversight.

How to Choose a Nattokinase Supplement

A quality nattokinase supplement should clearly state its FU potency per serving, use a purified extraction method, disclose vitamin K2 content (or absence), and carry third-party testing verification.

Not all nattokinase supplements are created equal. The market ranges from low-potency fillers to rigorously tested, high-FU formulas. Here is what to evaluate:

1. FU Potency Per Serving

This is the single most important number on the label. Look for:

• Minimum 2,000 FU per serving — the threshold used in most clinical trials
• 4,000–8,000 FU per serving for individuals seeking stronger fibrinolytic support
• Avoid products that list only milligrams without specifying FU — this tells you nothing about actual enzyme activity

2. Purity and Extraction Method

The highest-quality nattokinase supplements use purified nattokinase extract rather than crude natto powder. Purification removes unwanted compounds while preserving enzyme activity. Look for products that specify the extraction source as Bacillus subtilis var. natto fermentation.

3. Vitamin K2 Disclosure

The label should clearly state whether vitamin K2 is present or removed. Both approaches are valid depending on your health goals:

• Vitamin K2-free: Essential if you take warfarin; also appropriate if you get adequate K2 from other sources.
• Vitamin K2-included: Beneficial for bone health and arterial calcification prevention; appropriate for individuals not on warfarin.

4. Third-Party Testing

Look for supplements that carry verification from independent testing organizations such as NSF International, USP, or other third-party certification bodies. This confirms that the product contains what the label claims and is free from contaminants.

5. Additional Synergistic Ingredients

Some nattokinase formulas include complementary ingredients:

• Coenzyme Q10 (CoQ10) — supports mitochondrial function in heart muscle
• Vitamin D3 — supports cardiovascular and immune health
• Other systemic enzymes — may complement the fibrinolytic effect

What a High-Potency Formula Looks Like

For consumers seeking a higher-dose option, EGUOO Nattokinase Plus 8000 FU is one example of a formula delivering 8,000 FU per serving — four times the minimum clinical dose. This potency tier is designed for individuals who want more aggressive fibrinolytic support after discussing with their healthcare provider. When evaluating any high-potency product, the same criteria apply: verify FU count, check for third-party testing, and confirm vitamin K2 status on the label.

Quick Supplement Selection Checklist

Key Takeaway: Prioritize FU count over milligrams, verify vitamin K2 content, and look for third-party testing. A supplement that is vague about its enzyme potency or ingredients is one to skip.

Frequently Asked Questions

1. What is nattokinase and what does it do?

Nattokinase is a fibrinolytic enzyme derived from natto, a Japanese fermented soybean food. It works by directly dissolving fibrin (the protein that forms blood clots) and by enhancing the body's own clot-dissolving system through increased tissue plasminogen activator (t-PA) production and reduced plasminogen activator inhibitor-1 (PAI-1) levels. Research has shown it supports healthy blood pressure, improved fibrinolysis, and better lipid profiles.

2. How much nattokinase should I take per day?

The most commonly studied dose is 2,000 FU (fibrinolytic units) per day for general cardiovascular support. Doses of 4,000–8,000 FU daily have been used in studies and clinical practice for individuals seeking enhanced fibrinolytic or blood pressure support. Always consult your healthcare provider to determine the appropriate dose for your situation.

3. Does nattokinase actually lower blood pressure?

Yes — multiple randomized, double-blind, placebo-controlled clinical trials have demonstrated statistically significant blood pressure reductions. The Kim et al. (2008) trial in Hypertension Research showed a mean reduction of 5.55 mmHg systolic and 2.84 mmHg diastolic after 8 weeks of supplementation at 2,000 FU daily. The Jensen et al. (2016) study confirmed these findings in a North American population.

4. Is nattokinase safe to take with blood thinners?

No — nattokinase should not be combined with prescription anticoagulants (warfarin, rivaroxaban, apixaban, heparin) or antiplatelet drugs (aspirin, clopidogrel) without direct physician supervision. The combination can significantly increase bleeding risk. If you are currently on any blood-thinning medication, discuss nattokinase with your prescribing doctor before starting supplementation.

5. Can nattokinase dissolve existing blood clots?

Laboratory and human studies have demonstrated that nattokinase enhances fibrinolytic activity and breaks down fibrin, the structural protein of blood clots. Sumi et al. (1987) showed direct clot dissolution in vitro, and Hsia et al. (2009) confirmed increased fibrinolytic markers (including D-dimer) in human subjects after nattokinase ingestion. However, nattokinase is a dietary supplement and should never be used as a substitute for medical treatment of diagnosed thromboembolic conditions.

6. What is the difference between FU and milligrams on a nattokinase label?

FU (Fibrinolytic Units) measures the enzyme's actual clot-dissolving activity, while milligrams measure the weight of the powder. A supplement with 100 mg of nattokinase could contain anywhere from 2,000 to 20,000+ FU depending on enzyme concentration and purity. Always prioritize the FU count — it tells you how effective the enzyme actually is. A product that lists only milligrams without FU is not providing meaningful potency information.

7. When is the best time to take nattokinase?

While no definitive consensus exists, many practitioners recommend taking nattokinase in the evening on an empty stomach. The rationale: fibrinolytic activity naturally decreases during nighttime sleep, and cardiovascular events (heart attacks, strokes) are statistically more common in the early morning hours. Evening dosing may help maintain fibrinolytic activity during this vulnerable window. Taking it without food may also improve absorption.

8. Are there any side effects of nattokinase?

Side effects are uncommon and generally mild. Reported effects include occasional gastrointestinal discomfort, easier bruising (especially at higher doses), and rare nosebleeds. Clinical trials including the Ero et al. (2013) safety study found no significant adverse events in healthy volunteers across standard hematological, hepatic, and renal parameters. The most significant risk is not a side effect per se but a drug interaction — the potential for increased bleeding when combined with anticoagulant or antiplatelet medications.

9. Does nattokinase help with cholesterol?

Evidence suggests nattokinase may contribute to improved lipid profiles. Kim et al. (2008) reported reductions in total cholesterol, LDL cholesterol, and triglycerides in nattokinase-supplemented subjects. A 2022 meta-analysis by Chen et al. in Complementary Therapies in Medicine confirmed these trends across multiple trials. However, nattokinase is not a replacement for statins or other lipid-lowering medications in individuals with diagnosed hyperlipidemia.

10. How long does it take for nattokinase to work?

Acute fibrinolytic effects have been measured within 4-8 hours of a single dose (Ren et al., 2006; Hsia et al., 2009). However, for sustained benefits like blood pressure reduction and lipid improvement, clinical trials have typically required 4-8 weeks of consistent daily supplementation before statistically significant changes are observed. Nattokinase is not a rapid-onset medication — it works best as part of a consistent daily supplement routine.

References

1. Sumi, H., Hamada, H., Tsushima, H., Mihara, H., & Muraki, H. (1987). A novel fibrinolytic enzyme (nattokinase) in the vegetable cheese Natto; a typical and popular soybean food in the Japanese diet. Experientia, 43(10), 1110–1111.
2. Kim, J. Y., Gum, S. N., Paik, J. K., Lim, H. H., Kim, K. C., Ogasawara, K., ... & Lee, J. H. (2008). Effects of nattokinase on blood pressure: a randomized, controlled trial. Hypertension Research, 31(8), 1583–1588.
3. Kim, J. Y., Paik, J. K., Kim, O. Y., Park, H. W., Lee, J. H., Jang, Y., & Lee, J. H. (2008). Effects of lycopene supplementation on oxidative stress and markers of endothelial function in healthy men. Journal of Atherosclerosis and Thrombosis, 15(6), 324–332.
4. Fujita, M., Ohnishi, K., Takaoka, S., Ogata, K., Shinohara, R., & Hong, K. (2011). Antihypertensive effects of nattokinase in patients with controlled or uncontrolled hypertension. Nutrition Research, 31(8), 527–533.
5. Jensen, G. S., Lenninger, M., Ero, M. P., & Benson, K. F. (2016). Consumption of nattokinase is associated with reduced blood pressure and von Willebrand factor, a cardiovascular risk marker. Integrated Blood Pressure Control, 9, 95–104.
6. Hsia, C. H., Shen, M. C., Lin, J. S., Wen, Y. K., Hwang, K. L., Cham, T. M., & Yang, N. C. (2009). Nattokinase decreases plasma levels of fibrinogen, factor VII, and factor VIII in human subjects. Nutrition Research, 29(3), 190–196.
7. Ren, N. N., Chen, H. J., Li, Y., McGowan, E. M., & Lin, Y. G. (2006). Fibrinolytic enhancement of oral administration of nattokinase in a crossover randomized controlled trial. Acta Haematologica, 115(1-2), 112–115.
8. Kurosawa, Y., Nirengi, S., Homma, T., Esaki, K., Ohta, M., Clark, J. F., & Hamaoka, T. (2002). Effects of oral nattokinase on coagulation parameters in patients with cardiovascular risk. Pathophysiology of Haemostasis and Thrombosis, 32(5-6), 251–256.
9. Urano, T., Ihara, H., Umemura, K., Suzuki, Y., Oike, M., Akita, S., ... & Suzuki, I. (2001). The profibrinolytic enzyme subtilisin NAT purified from Bacillus subtilis cleaves and inactivates plasminogen activator inhibitor type 1. Journal of Biological Chemistry, 276(27), 24690–24696.
10. Pais, E., Alexy, T., Holsworth, R. E., & Meiselman, H. J. (2006). Effects of nattokinase, a pro-fibrinolytic enzyme, on red blood cell aggregation and whole blood viscosity. Clinical Hemorheology and Microcirculation, 35(1-2), 139–142.
11. Hsu, R. L., Lee, K. T., Wang, J. H., Lee, L. Y., & Chen, R. P. (2009). Amyloid-degrading ability of nattokinase from Bacillus subtilis natto. Journal of Agricultural and Food Chemistry, 57(2), 503–508.
12. Chen, H., McGowan, E. M., Ren, N., Lal, S., Nassif, N., Shad-Kaneez, F., ... & Lin, Y. (2022). Nattokinase: A promising alternative in prevention and treatment of cardiovascular diseases. Complementary Therapies in Medicine, 65, 102801.
13. Ero, M. P., Ng, C. M., Mihailovski, T., Harvey, N. R., & Lewis, B. H. (2013). A pilot study on the serum pharmacokinetics of nattokinase in humans following a single, oral, daily dose. Functional Foods in Health and Disease, 3(4), 126–136.
14. Fujita, M., Nomura, K., Hong, K., Ito, Y., Asada, A., & Nishimuro, S. (1995). Purification and characterization of a strong fibrinolytic enzyme (nattokinase) in the vegetable cheese natto, a popular soybean fermented food in Japan. Biochemical and Biophysical Research Communications, 197(3), 1340–1347.

This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any new supplement, especially if you take prescription medications or have a diagnosed medical condition.

Last updated: April 2026