Nattokinase: Enzyme Activity, FU Potency & Human Research

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Nattokinase

This page is part of the AMLApure Nattokinase Science & Education hub and the AMLApure Ingredient Science Library. It is intended for holistic, integrative, and nutrition-focused healthcare professionals and scientifically interested consumers. This content is educational in nature and does not constitute medical advice.

What Is Nattokinase?

Nattokinase is a serine protease enzyme associated with Bacillus subtilis var. natto — the bacterium responsible for fermenting soybeans into natto, the traditional Japanese food. The enzyme was first isolated and characterized in 1987 by Dr. Hiroyuki Sumi, who identified fibrinolytic activity in the natto preparation.

Nattokinase preparations are not the same as eating natto. Commercial nattokinase is an extracted, purified, and standardized enzyme preparation derived from the fermentation process. It is produced under controlled manufacturing conditions and tested for enzyme activity — not simply dried or powdered natto. Eating natto provides a complex whole-food profile including Vitamin K2, dietary fiber, and other fermented food compounds; a nattokinase supplement provides a concentrated, standardized fibrinolytic enzyme preparation, typically manufactured to be Vitamin K2-free.

For a detailed account of the distinction, see Nattokinase vs Natto: What's the Difference?

How Nattokinase Is Produced

Commercial nattokinase is produced through controlled fermentation of Bacillus subtilis var. natto. The fermentation process generates the enzyme, which is subsequently extracted, purified, and concentrated from the fermented material.

After extraction, the enzyme preparation is processed, standardized to an activity specification, tested for identity and purity, and typically tested for Vitamin K2 removal — an important consideration for individuals who may be sensitive to Vitamin K2's effects on coagulation.

For a more detailed explanation of the manufacturing process, see How Is Nattokinase Made? Fermentation Explained.

What Does FU Mean?

FU stands for Fibrinolytic Units — a measure of fibrinolytic enzyme activity determined under specified assay conditions. FU is the standard unit used to express nattokinase enzyme potency in nutritional formulations.

Understanding FU is important because:

  • FU measures what the enzyme does — its capacity to catalyze the breakdown of fibrin under the assay conditions
  • Milligrams measure weight only — they do not measure enzymatic activity
  • Two nattokinase preparations with identical milligram weights can have meaningfully different FU values depending on the enzyme's activity concentration

For a thorough explanation, see What Does FU Mean in Nattokinase?

Milligrams vs Enzyme Activity

Milligrams = weight of the ingredient.
FU = measured enzyme activity under specified assay conditions.

These are not interchangeable. A higher milligram amount does not automatically mean higher enzyme activity. Important: Higher FU does not automatically predict a superior clinical outcome. FU measures analytical enzyme activity in a standardized assay — not a clinical result in a human body.

Nattokinase, Circulation & Fibrin Research

Nattokinase has been the subject of scientific research primarily focused on its fibrinolytic properties — specifically its capacity to act on fibrin, a structural protein involved in the normal clotting process.

Types of evidence — clearly distinguished:

In vitro (laboratory): Nattokinase has demonstrated fibrinolytic activity in numerous laboratory assays. Laboratory findings do not automatically translate to equivalent effects in humans.

Animal research: Animal model studies have examined nattokinase in contexts involving blood viscosity and circulation-related markers. Animal findings are not directly applicable to human physiology without supportive human clinical evidence.

Human research: A body of human research exists, including pilot studies and some randomized controlled trials examining nattokinase in the context of circulation-related biomarkers, blood viscosity, and cardiovascular wellness indicators.

Nothing on this page constitutes a claim that nattokinase treats, prevents, cures, or dissolves blood clots, thrombosis, stroke, heart attack, hypertension, or any cardiovascular disease.

What Human Research on Nattokinase Shows

Areas with published human research:

  • Blood viscosity and hemorheology: Several small human studies have examined nattokinase in the context of blood viscosity markers.
  • Fibrin-related biomarkers: Human pilot studies have measured changes in fibrinogen and related markers following nattokinase supplementation.
  • Cardiovascular wellness indicators: One published RCT (Kim et al., 2008, Hypertension Research) examined nattokinase supplementation in a human cohort and reported changes in blood pressure markers over 8 weeks.
  • Combination studies: Some human research involves nattokinase in multi-ingredient formulations, making it difficult to isolate nattokinase's contribution alone.

No statements on this page should be interpreted as claims that nattokinase or AMLApure products diagnose, treat, cure, or prevent any disease.

External resource: PubMed — nattokinase human clinical research

Understanding FU Potencies in Formulations

AMLApure offers nattokinase formulations across a range of FU levels:

Browse all formulations: Nattokinase — AMLApure Science Hub collection

Multi-Ingredient Formulations

AMLA (Indian Gooseberry): Several AMLApure formulations combine nattokinase with Organic AMLA. See Amla Ingredient Science Library.

Bergamot: AMLApure's Nattokinase 4K + Bergamot formula adds Citrus bergamia polyphenols.

Quercetin, Bromelain, and Vitamin C: The Enterinex™ range combines nattokinase with multiple enzyme and antioxidant botanicals. See Sophora japonica and quercetin science.

Omega-3 (DHA & EPA): AMLApure's Omega-3 tincture pairs algae-derived DHA and EPA with amla extract. See AMLA and omega-3 formulation science.

This page is part of the AMLApure Ingredient Science Library. Content is educational and does not constitute medical advice. These statements have not been evaluated by the FDA. AMLApure products are not intended to diagnose, treat, cure, or prevent any disease.