Nattokinase

enzyme

What is it

Nattokinase is a fibrinolytic enzyme isolated from natto, a traditional Japanese fermented soybean food made with Bacillus subtilis natto. It is marketed primarily for cardiovascular support, including effects on fibrin breakdown, blood pressure, and circulation.

How it works

Nattokinase is a serine protease that breaks down fibrin, the protein that forms blood clots. By promoting fibrinolysis, nattokinase may help prevent or dissolve unwanted clots. It also appears to enhance the production of plasmin (the body's natural clot-dissolving enzyme) and reduce levels of prothrombotic factors like PAI-1 (plasminogen activator inhibitor-1). In addition to fibrinolytic effects, nattokinase has been studied for blood pressure reduction, where it may modestly lower systolic blood pressure through effects on the renin-angiotensin system or direct vascular activity. It may also reduce blood viscosity and modestly improve markers of arterial health. Oral nattokinase is absorbed intact in measurable amounts (unusual for a protein), with bioactive effects detectable after typical supplement doses. Activity is measured in fibrinolytic units (FU), with most products providing 2,000-4,000 FU per serving.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Blood pressure reduction

Grade B

Good evidence

Several trials show nattokinase modestly lowers systolic blood pressure (typically 4-10 mmHg) in people with prehypertension or mild hypertension over 8 weeks. Effects are modest compared with antihypertensive medications.

Cardiovascular / fibrinolytic support

Grade C

Moderate evidence

Multiple studies show nattokinase increases fibrinolytic activity and may reduce markers of clot formation. Effects on hard cardiovascular outcomes (heart attacks, strokes) have not been established in large trials, but the mechanism is well-characterized.

Deep vein thrombosis (DVT) prevention

Grade C

Moderate evidence

Some studies in long-haul travelers and immobilized patients suggest nattokinase may reduce DVT markers. Not a substitute for pharmacologic anticoagulation in high-risk situations.

Atherosclerosis markers

Grade C

Moderate evidence

Limited evidence suggests possible reductions in carotid intima-media thickness with long-term use. Evidence base is preliminary.

Post-COVID inflammation / clotting (preliminary)

Grade D

Mixed evidence

Some preliminary interest in nattokinase for post-COVID circulatory complications based on mechanism. Clinical evidence is limited and emerging.

2 commercial forms

Standardized nattokinase (NSK-SD)

Most clinical research uses this branded form, which guarantees vitamin K2 removal and consistent fibrinolytic activity.

The form used in most published clinical trials. Vitamin K2 is removed to avoid antagonizing the fibrinolytic effect.

Generic nattokinase

Activity varies; check fibrinolytic units (FU) per serving.

Less standardized; quality varies by manufacturer.

Dosage

Typical doses are 100-200 mg/day, providing 2,000-4,000 fibrinolytic units (FU). Studies on cardiovascular endpoints have used 2,000-6,000 FU/day. Take on an empty stomach for best absorption. No formal UL; doses up to 8,000 FU/day appear well-tolerated short-term.

When and how to take it

Take on an empty stomach (at least 30 minutes before meals or 2 hours after) for best absorption. Some users dose once daily in the evening; others split between morning and evening. Consistency matters for cardiovascular effects. Stop at least 2 weeks before any surgery, dental work, or procedure that may bleed.

Food sources

Food	Amount	%DV
Natto (fermented soybeans, 1/2 cup)	Naturally rich in nattokinase	—

Safety

Nattokinase is generally well-tolerated. The main safety concern is bleeding risk, particularly when combined with anticoagulants, antiplatelet drugs, or other fibrinolytic agents. Side effects can include GI upset, headache, and (rarely) allergic reactions (especially in those allergic to soy). Long-term safety data are limited but accumulating from clinical trials.

Who should be cautious

Avoid in active bleeding, bleeding disorders, or before any surgery (stop 2 weeks prior). Caution with all anticoagulants and antiplatelet drugs. Avoid in soy allergy. Avoid in pregnancy and lactation. Caution in active peptic ulcer disease, recent stroke, or uncontrolled hypertension. Discuss with cardiologist before adding to cardiovascular regimen.

Interactions

Significantly increases bleeding risk when combined with warfarin, aspirin, clopidogrel, heparin, or other anticoagulants/antiplatelets. May potentiate fibrinolytic drugs. Caution with NSAIDs. Vitamin K does not antagonize nattokinase (unlike warfarin). May enhance effects of blood pressure medications.

Frequently asked questions

Is nattokinase the same as natto?⌄

Natto is the fermented soybean food. Nattokinase is the specific fibrinolytic enzyme isolated from natto. Eating natto provides nattokinase plus other nutrients (including vitamin K2).

Can nattokinase replace blood thinners?⌄

No. Nattokinase has modest fibrinolytic effects but is not a substitute for prescription anticoagulants in conditions requiring strong clot prevention (atrial fibrillation, prior DVT, mechanical heart valves).

Will nattokinase lower my blood pressure?⌄

Studies show modest reductions in systolic blood pressure (4-10 mmHg). Useful as an adjunct for borderline hypertension but not a substitute for prescription antihypertensives in significant hypertension.

Is nattokinase safe with blood thinners?⌄

Combining significantly raises bleeding risk. Do not combine without your prescriber's explicit guidance and monitoring.

Should I stop before surgery?⌄

Yes. Stop at least 2 weeks before any planned surgery, dental procedure, or anything that could bleed. Resume after as directed by your surgeon.

References

Nattokinase - Wikidata — Wikidata link

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.