Nattokinase: Small Blood Pressure Drops in Short Trials, but No Artery Benefit Over 3 Years

Nattokinase is an enzyme from natto, a fermented soybean food, sold for blood pressure, circulation and "clot-busting". Short trials found small drops in blood pressure, but the longest placebo-controlled trial found no effect on artery thickening, blood pressure or clotting tests. Here is what each trial found, who paid for it, and who should be careful.

By Kymata Health Editorial Published Last checked

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Key takeaways

From 10 sources
  • A 2023 meta-analysis of 6 trials (546 people) found systolic blood pressure 3.45 mmHg and diastolic 2.32 mmHg lower on nattokinase than placebo, a small effect1.
  • The same analysis found total and LDL cholesterol slightly higher and HDL slightly lower at lower total doses, and blood glucose slightly higher, so the overall picture is mixed1.
  • The longest placebo-controlled trial, 265 adults followed for a median of 3 years on 2,000 FU a day, found no effect on carotid artery thickening, artery stiffness, blood pressure or any blood test, including clotting factors2.
  • A Chinese study that reported shrinking carotid plaque at 10,800 FU a day had no placebo group, and five of its authors were employed by Sungen Bioscience5.
  • Nattokinase has clot-dissolving activity, and a cerebellar bleed was reported in a man who took it with aspirin78; people on blood thinners were excluded from the 3-year trial, so its safety data do not cover them2.

Researched and written by Kymata Health Editorial; sources cited inline. Drawn from the studies cited below. Educational only, not medical advice.

What this article covers

1 evidence profile

The evidence, graded

Pulled from the trial tables in our evidence profiles. Grades follow our evidence-grading policy.

Graded findings

5 rows
  1. Grade CBlood pressure, lipids and glucoseMixed Systolic BP fell 3.45 mmHg and diastolic 2.32 mmHg versus placebo, but total and LDL cholesterol rose slightly at lower doses and blood glucose rose 0.40 units; HDL fell at lower doses. No notable adverse events.Nattokinase · Meta-analysis · n=546 · 2023 · PMID 39076715
  2. No effectCarotid atherosclerosis progression, blood pressure and clotting markersNo effect Annual change in carotid intima-media thickness and arterial stiffness did not differ from placebo, and there was no effect on blood pressure or any laboratory measure, including coagulation and fibrinolysis factors.Nattokinase · RCT · n=265 · 2021 · PMID 33843667
  3. Grade CBlood pressure in prehypertension or stage 1 hypertensionImproved Net changes versus placebo were −5.55 mmHg systolic and −2.84 mmHg diastolic (both p<0.05); plasma renin activity also fell.Nattokinase · RCT · n=86 · 2008 · PMID 18971533
  4. Grade DBlood pressure in a North American hypertensive populationImproved Diastolic BP fell from 87 to 84 mmHg versus no change on placebo (p<0.05), with larger drops in men; systolic reductions were reported for both sexes.Nattokinase · RCT · n=79 · 2016 · PMID 27785095
  5. Grade DCarotid plaque and lipids at high doseImproved Carotid intima-media thickness, plaque size and lipids improved at 10,800 FU/day, but 3,600 FU/day was ineffective. No noticeable adverse effects were recorded.Nattokinase · Open-label trial · n=1,062 · 2022 · PMID 36072877

Where these trials agree: Nattokinase and blood pressure, counted row by row in the Consensus finder.

What nattokinase is

Nattokinase is an enzyme made by the bacterium Bacillus subtilis when it ferments soybeans into natto, a traditional Japanese food9. It has fibrinolytic, or clot-dissolving, activity, which is why it is marketed for circulation9.

Labels give its strength in fibrinolytic units (FU), a measure of enzyme activity rather than weight, so a capsule's milligram count does not tell you its potency. The trials below used 2,000 to 10,800 FU a day25.

Blood pressure: small drops in short trials

In a Korean trial, 86 adults aged 20 to 80 with untreated systolic pressure of 130 to 159 mmHg took 2,000 FU of nattokinase or placebo daily for 8 weeks; 73 finished3. Compared with placebo, systolic pressure fell by a net 5.55 mmHg and diastolic by 2.84 mmHg3. Its PubMed record does not state who funded it.

In a North American trial, 79 adults with raised blood pressure took 100 mg a day of a nattokinase extract with its vitamin K2 removed, or placebo, for 8 weeks; 74 finished4. Average diastolic pressure fell from 87 to 84 mmHg on nattokinase while it stayed at 87 mmHg on placebo, with a larger drop in men4. The study was sponsored by JBSL-USA, the distributor of the tested product, and run by a contract research organization4.

A 2023 meta-analysis that pooled 6 randomized trials (546 people) found systolic pressure 3.45 mmHg and diastolic 2.32 mmHg lower than placebo1. It also found slightly higher total and LDL cholesterol and lower HDL at lower total doses, and slightly higher blood glucose1. The review was registered in advance, and its authors declared no conflicts of interest1.

The 3-year trial that found nothing

The Nattokinase Atherothrombotic Prevention Study randomized 265 adults with a median age of 65 and no known heart disease to 2,000 FU of nattokinase or placebo daily2. After a median of 3 years, the yearly change in carotid artery wall thickness and stiffness did not differ between groups, and there was no effect on blood pressure or any laboratory measure, including clotting and clot-dissolving factors2.

The trial was funded by the Helen Diller Family Foundation; Jarrow Formulas made and donated the capsules, and Japan Bio Life Sciences donated the nattokinase ingredient, per the published paper2. The paper states that no company had a role in collecting or analysing the data2.

The common label dose of 2,000 FU a day is the dose this trial tested2. For other supplements studied for blood pressure, see our explainers on garlic, beetroot juice and potassium.

High-dose plaque claims

A Chinese study gave 1,062 people with atherosclerosis or high blood lipids 10,800 FU a day for 12 months and reported thinner carotid artery walls, smaller plaques and better lipids, while 3,600 FU a day had no effect5. It had no placebo group, and five authors were employed by Sungen Bioscience and one by Sinopharm, per the paper's conflict statement5.

A 2026 Chinese trial of 120 adults with narrowed head or neck arteries but no symptoms gave 8,000 FU a day or placebo for 6 months; global thinking scores did not differ from placebo6. Only 88 people took the capsules as required and completed follow-up, and the authors declared no conflicts of interest6.

The nattokinase page grades each of these findings.

Who should be careful

Check with a doctor or pharmacist before taking nattokinase if any of these apply:

  • Blood thinners or antiplatelet drugs (such as warfarin, apixaban, clopidogrel or daily aspirin): a 2025 review notes that nattokinase's use may be limited by bleeding risk and drug interactions7. A man taking aspirin had a cerebellar bleed after 7 days of nattokinase 400 mg a day8. The 3-year trial excluded people on these drugs, so its reassuring safety data do not apply to them2.
  • Warfarin specifically: vitamin K counteracts warfarin, and a sudden change in vitamin K intake can cause bleeding or clots10. Fermented foods such as natto supply vitamin K210, and the North American trial product had its vitamin K2 removed4, so check the label.
  • Bleeding disorders or upcoming surgery: because nattokinase has clot-dissolving activity9, tell your surgical team; there are no human data on how long before surgery to stop it.
  • Soy allergy: nattokinase is produced by fermenting soybeans9, and the 3-year trial excluded people with soy allergy2.
  • High blood pressure: the Korean trial enrolled people who were not taking blood pressure medicine3, so they say nothing about adding nattokinase to blood pressure drugs, and a supplement is not a substitute for prescribed treatment.
  • Pregnancy or breastfeeding: none of the trials described here studied these groups.

Quick answers

Common questions

4 answers
How much nattokinase was used in the trials?

Most trials used 2,000 FU a day23; one North American trial used 100 mg a day of an extract4, and Chinese studies used 8,000 to 10,800 FU a day56.

Does nattokinase dissolve blood clots?

It has clot-dissolving (fibrinolytic) activity9, but in the 3-year human trial, 2,000 FU a day did not change any clotting or clot-dissolving blood test2.

Can I take nattokinase with aspirin or a blood thinner?

That combination was not tested in the placebo-controlled trials, which excluded people on these drugs2, and a bleed has been reported with aspirin8. It is a question for the prescriber.

How long does it take nattokinase to lower blood pressure?

The trials that found small drops measured blood pressure after 8 weeks34, while the 3-year trial found no blood pressure effect at all2.

Keep reading

Full evidence profiles

Every graded study, studied doses, interactions and safety

Related articles

4 articles

Browse the full Supplement & Nutrient Encyclopedia or all supplement articles.

Where to buy Nattokinase

Products from brands we partner with that contain Nattokinase. Check the amount per serving against the doses studied, and the label for other ingredients.

Nattokinase products from partner brands

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  • Quick pickHerbsProNOW Foods Nattokinase, 100 mg, 60 Vcaps

    1 veg capsule: 100 mg nattokinase (2,000 FU enzyme activity)

    $16.74one-timeChecked Oct 14, 2026
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    2 capsules: 100 mg fermented soybean extract providing 2,000 FU of nattokinase; 30 servings

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References

10 sources. Numbers in the text link here.

Sources cited in this article

10 sources
  1. 1Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled TrialsRev Cardiovasc Med, 2023 · PMID 39076715
  2. 2Nattokinase atherothrombotic prevention study: A randomized controlled trialClin Hemorheol Microcirc, 2021 · PMID 33843667
  3. 3Effects of nattokinase on blood pressure: a randomized, controlled trialHypertens Res, 2008 · PMID 18971533
  4. 4Consumption of nattokinase is associated with reduced blood pressure and von Willebrand factor, a cardiovascular risk marker: results from a randomized, double-blind, placebo-controlled, multicenter North American clinical trialIntegr Blood Press Control, 2016 · PMID 27785095
  5. 5Effective management of atherosclerosis progress and hyperlipidemia with nattokinase: A clinical study with 1,062 participantsFront Cardiovasc Med, 2022 · PMID 36072877
  6. 6Nattokinase supplementation for cognitive enhancement in asymptomatic intracranial/carotid stenosis: A randomized controlled trialJ Stroke Cerebrovasc Dis, 2026 · PMID 41325794
  7. 7Navigating the Effects of Anti-Atherosclerotic Supplements and Acknowledging Associated Bleeding RisksInt J Mol Sci, 2025 · PMID 41155474
  8. 8Cerebellar hemorrhage provoked by combined use of nattokinase and aspirin in a patient with cerebral microbleedsIntern Med, 2008 · PMID 18310985
  9. 9Nattokinase: An Oral Antithrombotic Agent for the Prevention of Cardiovascular DiseaseInt J Mol Sci, 2017 · PMID 28264497
  10. 10Vitamin K: Fact Sheet for ConsumersNIH Office of Dietary Supplements, 2021

Nattokinase and other dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Talk to your clinician or pharmacist before starting a supplement, especially if you take prescription medicines. Product links on this page are paid partner links.

Educational only. Not medical advice. Some links earn us a commission: kymatahealth.com/affiliate-disclosure.