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HEART & CIRCULATION

Nattokinase (NSK-SD)

Circulation · fibrin breakdown · clot prevention

MODERATE EVIDENCEVEGANREAD THE RESEARCH
Written to our editorial standards · reviewed against published research· Updated 2 Jun 2026
Last reviewed: May 30, 2026
QUICK ANSWER

Nattokinase: Circulation · fibrin breakdown · clot prevention. Enzyme isolated from fermented soybeans (natto). Supports healthy blood flow by promoting normal fibrin breakdown. Standard dose 100 mg (2000 FU), taken in the morning, about $19/month. Evidence rating: moderate evidence.

What is Nattokinase?

Nattokinase is a proteolytic enzyme produced when soybeans are fermented with Bacillus subtilis natto, creating the traditional Japanese food natto. The enzyme has documented fibrinolytic activity, meaning it helps the body break down fibrin, the protein meshwork involved in blood clot formation. Clinical research suggests benefits for circulatory health, healthy blood viscosity, and post-flight leg circulation. Because of these effects on the clotting system, nattokinase should be discontinued at least two weeks before any scheduled surgery and is not appropriate for people on blood-thinning medications without clinician oversight. Standard dose is 100 mg (2,000 Fibrinolytic Units) per day on an empty stomach.

WHY IT MATTERS

Enzyme isolated from fermented soybeans (natto). Supports healthy blood flow by promoting normal fibrin breakdown.

Natural food sources

Where possible, get Nattokinase from whole foods first. Common dietary sources include:

Natto (fermented soybeans)

Where to buy

Doctor's Best Nattokinase 2000 FU
RECOMMENDED
Doctor's Best, Nattokinase
100 mg (2000 FU) · Morning · ~$19/month

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Common questions

What is Nattokinase?
Nattokinase is a proteolytic enzyme produced when soybeans are fermented with Bacillus subtilis natto, creating the traditional Japanese food natto. The enzyme has documented fibrinolytic activity, meaning it helps the body break down fibrin, the protein meshwork involved in blood clot formation. Clinical research suggests benefits for circulatory health, healthy blood viscosity, and post-flight leg circulation. Because of these effects on the clotting system, nattokinase should be discontinued at least two weeks before any scheduled surgery and is not appropriate for people on blood-thinning medications without clinician oversight. Standard dose is 100 mg (2,000 Fibrinolytic Units) per day on an empty stomach.
What is Nattokinase used for?
Circulation · fibrin breakdown · clot prevention. Enzyme isolated from fermented soybeans (natto). Supports healthy blood flow by promoting normal fibrin breakdown.
What is the standard dose of Nattokinase?
100 mg (2000 FU), typically taken in the morning. Approximate cost is $19 per month.
Who should avoid Nattokinase?
Use extra caution, and speak to a clinician first, if you are on blood thinners, pregnant or nursing.
How strong is the evidence for Nattokinase?
Moderate evidence for its primary uses. See the full study list on the research page.

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