Nattokinase
An enzyme from natto · fermented-soybean origin, and an allergen to declare
All articles checked for accuracy against the GB NHC Register and all sources have citations with verified links to their relevant studies.
Nattokinase is an enzyme made when soybeans are fermented into natto. It is measured by its activity, not just weight, and because it comes from soy it is an allergen that must be declared.
This article explains what nattokinase is, why fibrinolytic units (FU) are the meaningful measure, where the ingredient comes from, and the regulatory position on claims and safety. It keeps strictly to published research and regulatory honesty rather than making health claims.
Ingredient Snapshot
- What it is
- An enzyme produced during the fermentation of soybeans into natto.
- Where from
- Produced by Bacillus subtilis var. natto fermenting soybeans (natto).
- Known for
- Measured by fibrinolytic units (FU); derived from soybean and contains soya allergen.
- In WellsparQ
- NattakoComplex100 mg (from fermented soybean extract — contains soya)
Nattokinase is an enzyme with an unusually specific origin: it is produced during the fermentation of soybeans into natto, a traditional Japanese food. Two things make it worth a careful page — its measurement is unusual (activity, not just weight), and its raw material is soy, a declarable allergen. This piece covers the biology, the units, the sourcing and the safety, and keeps well clear of any claim the ingredient is not allowed to carry.
Where it comes from
Natto is made by fermenting cooked soybeans with the bacterium Bacillus subtilis var. natto. During fermentation the bacterium secretes a range of enzymes, one of which — nattokinase — was identified in the 1980s as a protease with fibrinolytic activity in the laboratory, meaning it can break down fibrin, the protein that forms the mesh of a blood clot, in a test-tube setting ¹. The name simply joins natto to the enzyme suffix -kinase.
Two points of honesty at the outset. First, "fibrinolytic activity in the laboratory" describes what the enzyme does to fibrin in a dish; it is not a statement about what a capsule does in a person, and must not be read as one. Second, nattokinase is an enzyme, and enzymes carry no authorised health claim — so this page discusses research strictly as research.
The unit that matters: fibrinolytic units (FU)
Because nattokinase is valued for its enzyme activity rather than simply its mass, a milligram figure alone does not fully describe a dose. The meaningful measure is the fibrinolytic unit (FU) — a standardised measure of enzymatic activity. A well-specified nattokinase states its FU content, so that each capsule delivers a consistent, characterised amount of active enzyme rather than a variable weight of extract ¹.
| Attribute | Detail |
|---|---|
| Source organism | Bacillus subtilis var. natto, fermenting soybeans ¹ |
| Molecule type | A serine protease (enzyme) ¹ |
| Laboratory property | Fibrinolytic activity (breaks down fibrin in vitro) ¹ |
| Meaningful measure | Fibrinolytic units (FU) of activity, not milligrams alone ¹ |
| Raw material | Fermented soybean extract — a declarable allergen |
Reading the research
Nattokinase has been studied since its discovery, mostly in laboratory and animal models and in a scatter of small human studies. Reviews describe consistent in-vitro fibrinolytic activity and note that the human clinical evidence remains limited, of variable quality and preliminary, calling for larger and better-controlled trials ¹². That is the honest summary: an interesting enzyme with a clear laboratory property and an immature human evidence base.
WellsparQ reports this as the state of the evidence. Nattokinase carries no authorised health claim, and we make none.
How WellsparQ uses it
| WellsparQ product | Declared nattokinase | Activity | Note |
|---|---|---|---|
| NattakoComplex | 100 mg (from fermented soybean extract — contains soya) | 2,000 FU per capsule | "Standardised to 2,000 fibrinolytic units (FUs) per capsule — the measure that matters for a nattokinase formula" |
Source: WellsparQ Supplements Database. The formula states both the weight and the activity, which is exactly the transparency the ingredient demands. Because it is fermented from soybeans, nattokinase is plant-derived and suitable for vegetarians and vegans — but it contains soya and must be clearly declared as such for allergen safety.
Safety and sensible use — read this part
Nattokinase warrants more than a routine caution.
- Soy allergen. It is derived from soybean and contains soya; anyone with a soy allergy must avoid it, and the allergen must be declared prominently on-pack.
- Blood-clotting. Because of its laboratory fibrinolytic property, standard cautionary guidance is that nattokinase should be avoided by anyone taking anticoagulant or antiplatelet medicines (such as warfarin, DOACs, aspirin or clopidogrel), anyone with a bleeding disorder, and anyone due to have surgery — and it should be discussed with a GP or pharmacist first in all such cases ¹².
- General. Not for use in pregnancy or breastfeeding, or by under-18s, without professional advice.
Take only as directed, and treat the medication and allergen cautions as firm rather than optional.
References
- Peer-reviewed reviews of nattokinase — origin from Bacillus subtilis var. natto, serine-protease chemistry, fibrinolytic activity and unit (FU) measurement, and the preliminary state of human evidence (e.g. reviews in Biomarker Insights and Frontiers in Pharmacology/Nutrition). PMID 39404094 ↩ Back to text
- Clinical and safety reviews of nattokinase noting variable trial quality and standard bleeding/anticoagulant precautions. PMID 42097398 ↩ Back to text