Nattokinase benefits: what the research says
The short answer
Nattokinase is an enzyme from natto, a fermented soybean food, and it is studied for its role in normal circulation and blood pressure, with small trials suggesting a modest effect on blood pressure but no clear benefit for cholesterol or artery health.
It is also an ingredient that needs real care. Because it may affect how blood clots, it is not suitable for everyone, especially people who take blood-thinning medicines. Here is what the research says, in plain terms.
What is nattokinase?
Nattokinase is an enzyme made when soybeans are fermented with the bacterium Bacillus subtilis var. natto to make natto, a traditional Japanese food.
It is described as a fibrin-degrading enzyme. Fibrin is the protein mesh that holds a blood clot together, which is why nattokinase has attracted interest for circulation. Supplement doses are usually measured in fibrinolytic units (FU), a measure of enzyme activity, rather than milligrams.
What are the possible benefits of nattokinase?
The most consistent finding is a small reduction in blood pressure in short trials; other proposed benefits have weaker or negative evidence.
Blood pressure
A 2023 systematic review and meta-analysis pooled six randomised controlled trials with 546 participants. Nattokinase was linked to an average fall of about 3.45 mmHg in systolic blood pressure (the top number) and about 2.32 mmHg in diastolic blood pressure (the bottom number). The authors noted the total number of studies was small, so the findings should be read with caution.
An earlier randomised, placebo-controlled trial from 2008 gave 86 adults with raised but untreated blood pressure 2,000 FU of nattokinase or placebo for eight weeks. Systolic pressure fell by about 5.55 mmHg more with nattokinase than with placebo. The change in diastolic pressure was not statistically significant.
Cholesterol
The same 2023 meta-analysis found no lipid-lowering benefit. Lower total doses were linked to slightly higher total and LDL cholesterol and lower HDL cholesterol compared with control groups, and there was no effect on triglycerides. Nattokinase should not be thought of as a cholesterol supplement.
Artery health
The longest trial to date, the Nattokinase Atherothrombotic Prevention Study, followed 265 healthy adults with a median age of 65 for a median of three years. Taking 2,000 FU a day made no significant difference to the thickening or stiffening of the carotid arteries, and no significant difference to blood pressure or any laboratory measure, compared with placebo.
Nattokinase research at a glance
This table summarises the main human studies and what they found.
| Study | Who and how long | Dose | Main finding |
|---|---|---|---|
| Kim et al., 2008 | 86 adults with raised blood pressure, 8 weeks | 2,000 FU a day | Systolic pressure about 5.55 mmHg lower than placebo |
| Hodis et al., 2021 (NAPS) | 265 healthy adults, median 3 years | 2,000 FU a day | No significant effect on artery thickness, stiffness or blood pressure |
| Li et al., 2023 (meta-analysis) | 6 trials, 546 participants | Varied | Small fall in blood pressure; no lipid-lowering benefit |
How does that fit with heart health more widely?
Small changes in blood pressure are interesting, but they are not a reason to swap or skip any prescribed treatment.
The 2021 study showed that a modest effect in short trials did not translate into measurable changes in artery health over three years in healthy older adults. If you have high blood pressure, keep taking the medicines your doctor has prescribed and talk to them before adding any supplement.
Other nutrients have authorised heart-related claims. For example, EPA and DHA from omega-3 contribute to the normal function of the heart, and plant sterols contribute to the maintenance of normal blood cholesterol levels. Coenzyme Q10 is a compound central to cellular energy production, with heart and muscle cells holding the most.
Is nattokinase safe?
Nattokinase may increase the risk of bleeding, so it is not suitable for everyone.
In the trials above, no notable side effects were reported. However, Memorial Sloan Kettering Cancer Center's integrative medicine service advises that nattokinase may increase bleeding risk, may prolong some blood-clotting test results and, because of its clot-dissolving action, could in theory dislodge an existing clot. A case report has linked nattokinase taken with aspirin to bleeding in the brain, although a single case cannot prove cause.
Do not take nattokinase without medical advice if you:
- take anticoagulants such as warfarin or other blood thinners
- take antiplatelet medicines, including daily aspirin
- have a bleeding or clotting disorder, or a history of deep vein thrombosis
- are due to have surgery, a dental procedure or any other procedure
- are pregnant or breastfeeding
- have a soy allergy (check the product label for its source)
Natto as a food contains vitamin K, which can reduce the effect of warfarin. Do not assume a nattokinase supplement is free of vitamin K, and always speak to your GP or pharmacist first if you take warfarin.
How much nattokinase is used in studies?
The main human trials used 2,000 FU a day.
That figure gives a useful benchmark when reading labels. Look for a product that states its activity in FU, follow the serving size on the label, and do not take more than recommended. More is not better with an enzyme that may affect clotting.
Our approach
Nattokinase is best treated as a considered choice for healthy adults who have checked it suits them.
If you are not taking blood-thinning medicines and your GP or pharmacist is happy, our Nattokinase sits in our heart collection, alongside Coenzyme Q10 and Cholestilite, for people building a heart-focused daily protocol with care.
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