Supplements
Nattokinase: natto versus enzyme extracts, activity units, cardiovascular surrogate trials and bleeding concerns
On this page
Nattokinase is an enzyme obtained from natto, a fermented soybean food. Supplements concentrate an enzyme preparation rather than reproduce the whole food. It has fibrinolytic activity: laboratory effects on the breakdown of fibrin, a protein in blood clots. This creates a biological rationale for research, but it does not establish a safe self-directed blood thinner or a treatment that removes arterial plaque.[2]
Separate food, preparation weight and enzyme activity
| Form or concept | What it means | Boundary for interpreting research |
|---|---|---|
| Natto food | Fermented soybeans with many constituents | It contains vitamin K as well as an enzyme source[1] |
| Standardized extract | A specified fermented-soy preparation and carrier | One assessed extract does not represent every supplement[1] |
| Purified enzyme | Nattokinase as the enzyme component | Extract weight is not necessarily pure-enzyme weight[1] |
| Fibrinolytic units / FU | Activity measured by a specified laboratory assay | An activity number is not proof of benefit in a patient[1] |
| Milligrams / mg | Mass of a particular preparation | No universal mg-to-FU conversion applies to all products[1] |
FU and milligrams cannot be compared without product specifications
EFSA’s 2016 assessment described a particular extract with 20,000–28,000 FU per gram. For that specified preparation, 100 mg supplies 2,000–2,800 FU. That calculation depends on measured activity and composition; it cannot be applied to an arbitrary capsule. The assessment also distinguished safety from efficacy and did not establish absorption of active enzyme or functional metabolites.[1]
Evidence & uncertainty
A 2023 review found preliminary blood-pressure effects but no convincing lipid-lowering benefit across small randomized trials. Cardiovascular risk markers, clotting tests and clinical events are different outcomes. The review did not establish prevention of stroke, heart attack or venous thrombosis. Its varied populations, exposures and follow-up leave considerable uncertainty; neither the number of references nor the term fibrinolytic supplies the missing clinical evidence.[5]
Selected-source overview · Independent review pendingPublished questions
Is eating natto equivalent to taking a nattokinase extract?
Selected-source overview · Independent review pending. Read the evidence context.
No. Natto is a fermented food with multiple constituents. The standardized extract assessed by EFSA had specified composition, carrier and enzyme activity.[1]
Evidence behind this answer
- Safety of fermented soybean extract NSK-SD as a novel food
agency novel food safety assessment · 2016
Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal · 2016-07-28; Adopted 2016-06-28; composition, activity assay, vitamin K removal, absorption uncertainty and specified safety scope
This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.
Can milligrams of nattokinase always be converted into FU?
Selected-source overview · Independent review pending. Read the evidence context.
No. Conversion requires the particular preparation’s activity assay. FU measures enzyme activity; milligrams measure mass. One product’s specification does not apply universally.[1]
Evidence behind this answer
- Safety of fermented soybean extract NSK-SD as a novel food
agency novel food safety assessment · 2016
Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal · 2016-07-28; Adopted 2016-06-28; composition, activity assay, vitamin K removal, absorption uncertainty and specified safety scope
This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.
Do increased fibrin-breakdown markers prove nattokinase prevents stroke?
Selected-source overview · Independent review pending. Read the evidence context.
No. The twelve-man experiment measured acute laboratory changes over eight hours. It did not test prevention of stroke, heart attack or venous thrombosis.[3]
Evidence behind this answer
- A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles
original randomized crossover biomarker trial · 2015
Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal · 2015-06-25; 5:11601; twelve healthy men, single dose, eight-hour biomarkers and normal-range changes
This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.
Did the three-year randomized trial show nattokinase cleaned arteries?
Selected-source overview · Independent review pending. Read the evidence context.
No significant benefit was found for carotid thickness progression or stiffness in the studied adults. These surrogate findings do not support a routine artery-cleaning claim.[4]
Evidence behind this answer
- Nattokinase atherothrombotic prevention study: A randomized controlled trial
original randomized controlled trial · 2021
Original abstract and bibliographic record inspected on 2026-10-14 UTC; full text not inspected · 2021-04-02; Online date; 78(4):339–353; 265 participants, median three years, null carotid/pressure/laboratory results
This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.
Does the randomized-trial review establish reliable cholesterol lowering?
Selected-source overview · Independent review pending. Read the evidence context.
No. The review found no convincing lipid-lowering benefit. Its preliminary pooled pressure effect came from only three small trials.[5]
Evidence behind this answer
- Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
original systematic review · 2023
Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal · 2023-08-15; 24(8):234; seven/six trials, three-trial pressure pool, lipids, dose-duration categories and limitations
This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.
Can the combination trial prove that nattokinase alone caused its lipid improvement?
Selected-source overview · Independent review pending. Read the evidence context.
No. The combination also contained red yeast rice monacolins. The four-arm trial measured risk markers rather than demonstrated prevention of clinical thrombosis.[6]
Evidence behind this answer
- Lipid-lowering, antihypertensive, and antithrombotic effects of nattokinase combined with red yeast rice in patients with stable coronary artery disease
original randomized combination trial · 2024
Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal · 2024-05-15; 11:1380727; 178 participants, four arms, usual medication, 90-day markers, funding and employment disclosures
This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.
Can nattokinase replace warfarin for a mechanical heart valve?
Selected-source overview · Independent review pending. Read the evidence context.
No. A reported patient made that substitution and developed extensive valve thrombosis requiring repeat surgery. Laboratory fibrinolytic activity is not equivalent anticoagulation.[8]
Evidence behind this answer
- Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis
original case report · 2015
Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal · 2015-01; 28(1):81–82; stopped warfarin, approximately one year, valve thrombosis and repeat replacement
This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.
Is nattokinase automatically safe alongside aspirin or anticoagulants?
Selected-source overview · Independent review pending. Read the evidence context.
No. The clinical monograph warns of added bleeding concerns with these drugs and coagulation disorders. A vitamin-K-free label does not remove that concern.[2]
Evidence behind this answer
- Nattokinase
official clinical monograph · 2022
Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal · 2022-04-14; Updated date; clinical summary, coagulation warnings, drug interactions and raw-natto vitamin K distinction
This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.
What a clot-related biomarker experiment actually established
In 2015, twelve healthy young Japanese men completed a double-blind crossover study of a single 2,000-FU exposure versus placebo, followed for eight hours. Nattokinase changed selected fibrin-breakdown and coagulation measurements, including D-dimer, factor VIII activity and activated partial thromboplastin time. The changes stayed within normal ranges. This supports an acute biological effect in a small selected group; it does not show that a dangerous clot was treated or that future thrombosis was prevented. Timing-specific laboratory findings cannot determine who should take a supplement or what would happen during chronic use.[3]
A longer randomized prevention study was negative
The 2021 trial randomized 265 adults without clinical cardiovascular disease to nattokinase or placebo. Median age was 65.3 years, the tested exposure was 2,000 FU/day and median follow-up was three years. There was no significant benefit for carotid intima-media thickness progression, carotid stiffness, blood pressure or measured laboratory outcomes. These were mainly surrogate measures in relatively low-risk adults, not a definitive test of every population or formulation. Nevertheless, this longer negative trial directly limits routine claims that nattokinase cleans arteries or consistently improves cardiovascular risk. Only its abstract was inspected for this guide.[4]
The review’s blood-pressure signal was based on few trials
The 2023 review included seven randomized trials with 607 participants qualitatively and six with 546 participants quantitatively. Only three trials, involving 223 participants, supplied pooled blood-pressure results. Estimated systolic and diastolic reductions were approximately 3.45 and 2.32 mmHg compared with placebo. Lipid findings did not support a general cholesterol-lowering claim, and triglyceride effects were not significant. The review’s categories based on total exposure combine duration with amount; they cannot establish that a higher daily amount works better. A modest pressure average does not overcome the absence of demonstrated clinical-event prevention.[5]
A combination result cannot be credited to nattokinase alone
A 2024 four-arm trial enrolled 178 people with stable coronary artery disease for 90 days while usual medications continued. It compared nattokinase, red yeast rice, their combination and placebo. The combined preparation improved several lipid, pressure and coagulation markers more than the other groups. It also supplied monacolins, biologically active red-yeast-rice constituents, so these results cannot be attributed to nattokinase alone. No intervention-related adverse events were reported during the trial. Manufacturer foundation funding and several manufacturer-employed authors were disclosed. The study did not demonstrate fewer heart attacks or clinical thromboses.[6]
A severe bleeding report raises concern without estimating its frequency
A 2021 report described a 92-year-old woman with kidney disease and atrial fibrillation who developed abdominal bleeding after a fall and rupture of a hepatic cyst. She was taking nattokinase without another anticoagulant; the amount was unknown and sometimes reportedly excessive. She subsequently died. The report cannot prove that the enzyme caused the hemorrhage, isolate its contribution from the injury and cyst, or estimate risk at any standard amount. It is a safety signal, not reassurance that bleeding is confined to people taking prescription blood thinners.[7]
Replacing required anticoagulation has a documented harmful example
A 2015 report described a 53-year-old man with a mechanical aortic valve who stopped prescribed warfarin and used nattokinase for about a year. Extensive valve thrombosis developed, requiring another valve replacement. The case does not quantify the risk of every substitution, but it shows why an enzyme’s laboratory activity cannot be treated as equivalent anticoagulation. Nattokinase should not replace prescribed anticoagulants, antiplatelets, cholesterol treatment or blood-pressure treatment. Mechanical valves and other conditions requiring anticoagulation depend on clinical evidence and monitoring that a supplement label does not supply.[8]
Bleeding and raw-natto vitamin K are different concerns
Memorial Sloan Kettering’s clinical monograph warns against nattokinase with coagulation disorders, anticoagulants or daily aspirin, and describes potential added bleeding with antiplatelet or fibrinolytic drugs. Raw natto’s vitamin K may interfere with warfarin; this food interaction differs from the enzyme’s bleeding concern. Removing vitamin K from an extract does not prove that combining its enzyme activity with medicines is safe. Planned procedures and relevant allergies warrant clinician or pharmacist review; these sources do not establish a universal stop interval.[2]
The prevention claim remains the central unresolved question
The longer trial’s null results matter even though low-risk participants may differ from patients with vascular disease. Changing populations or increasing an untested exposure is a research proposal, not established effectiveness. Carotid measurements can test hypotheses, but a stroke-prevention product needs clinical-event evidence and an acceptable bleeding profile. The negative study leaves that claim unestablished; another commercial preparation cannot be assumed to have solved the problem.[4]
References
- Safety of fermented soybean extract NSK-SD as a novel food
Agency novel food safety assessment
EFSA NDA Panel · Content/publication date: 2016
Accessed: 2026-10-14 UTC · Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal
Cited sections: 2016-07-28; Adopted 2016-06-28; composition, activity assay, vitamin K removal, absorption uncertainty and specified safety scopeAssessment of specified NSK-SD at 100 mg/day for healthy adults over 35, excluding pregnancy/lactation; not an efficacy assessment.
- Nattokinase
Official clinical monograph
Memorial Sloan Kettering Cancer Center · Content/publication date: 2022
Accessed: 2026-10-14 UTC · Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal
Cited sections: 2022-04-14; Updated date; clinical summary, coagulation warnings, drug interactions and raw-natto vitamin K distinction - A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles
Original randomized crossover biomarker trial
Kurosawa and colleagues · Content/publication date: 2015
Accessed: 2026-10-14 UTC · Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal
Cited sections: 2015-06-25; 5:11601; twelve healthy men, single dose, eight-hour biomarkers and normal-range changes - Nattokinase atherothrombotic prevention study: A randomized controlled trial
Original randomized controlled trial
Hodis and colleagues · Content/publication date: 2021
Accessed: 2026-10-14 UTC · Original abstract and bibliographic record inspected on 2026-10-14 UTC; full text not inspected
Cited sections: 2021-04-02; Online date; 78(4):339–353; 265 participants, median three years, null carotid/pressure/laboratory results - Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Original systematic review
Li and colleagues · Content/publication date: 2023
Accessed: 2026-10-14 UTC · Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal
Cited sections: 2023-08-15; 24(8):234; seven/six trials, three-trial pressure pool, lipids, dose-duration categories and limitations - Lipid-lowering, antihypertensive, and antithrombotic effects of nattokinase combined with red yeast rice in patients with stable coronary artery disease
Original randomized combination trial
Liu and colleagues · Content/publication date: 2024
Accessed: 2026-10-14 UTC · Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal
Cited sections: 2024-05-15; 11:1380727; 178 participants, four arms, usual medication, 90-day markers, funding and employment disclosures - Nattokinase-Associated Hemoperitoneum in an Elderly Woman
Original case report
Ramachandran and colleagues · Content/publication date: 2021
Accessed: 2026-10-14 UTC · Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal
Cited sections: 2021-12-01; 13(12):e20074; elderly patient, fall, hepatic cyst, unknown exposure and causal uncertainty - Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis
Original case report
Elahi and colleagues · Content/publication date: 2015
Accessed: 2026-10-14 UTC · Selected original full-text definition, methods, results and discussion passages inspected on 2026-10-14 UTC; no independent systematic appraisal
Cited sections: 2015-01; 28(1):81–82; stopped warfarin, approximately one year, valve thrombosis and repeat replacement
Scope & review
- Population
- Source-specific adult participants; findings do not establish general use in pregnancy, breastfeeding or children
- Exposure or intervention
- Natto food, standardized fermented-soy extract, enzyme activity and specified nattokinase-only/combination trials
- Comparison
- Source-specific placebo, dietary form or alternative formulation; mechanisms and biomarkers are separated from patient-important outcomes
- Outcomes
- Activity units, acute coagulation markers, pressure/lipids, carotid surrogates, bleeding signals and medication substitution
- Timeframe
- Each experiment retains its stated follow-up; hours, weeks, months and observational years answer different questions
- Jurisdiction
- Selected international original research, original reviews and explicitly dated official assessments; product rules vary by jurisdiction
Selected-source educational explanation. Official guidance, original study findings and editorial interpretation are distinguished. No exhaustive search, independent systematic synthesis or qualified medical review has been completed.
Sources checked on their individual access dates. Selected sources were checked; ongoing surveillance and qualified review have separate statuses on the coverage page.
Revision history
- 2026-10-14 UTC: Added a bounded supplement guide with form distinctions, contrary findings and source-access limits; qualified review remains pending.
What this article still leaves open
- Do well-designed trials establish net clinical-event benefit while quantifying bleeding?
- Which preparations have reliable active-enzyme exposure and reproducible activity assays?
- What are interactions and safety in higher-risk patients, pregnancy, childhood and perioperative care?
Suggest a correction
Submit a content correction to the editorial queue, or download a local note. Leave out personal medical details. Submitted text is stored privately with a browser receipt session and is visible to this browser and the editor. Clearing cookies removes access to your submission history. This is not an account or a medical service.
Your submitted corrections for this article
Explore the topic map
Browse the health domains connected to this article. The map also identifies topics whose articles remain unwritten.