Nattokinase is an enzyme found in natto, a traditional Japanese food made from fermented soybeans

Nattokinase is a protein-digesting enzyme produced during the fermentation of soybeans into natto. It comes from a bacterium called Bacillus subtilis that grows on the soybeans during fermentation. The enzyme has been part of Japanese cuisine for centuries, but only in the last few decades have researchers begun studying whether it has effects on human health beyond nutrition.

The enzyme works by breaking down proteins. In the body, researchers have focused on whether nattokinase can break down fibrin, a protein involved in blood clotting. This is the main reason nattokinase appears in longevity and wellness discussions — the idea that it might support cardiovascular function by affecting how blood clots form.

Nattokinase is sold as a dietary supplement in capsule or powder form, separate from natto itself. The supplement is not approved by the FDA as a drug, and it is not the same as eating natto as food. Most nattokinase supplements are standardized to contain a specific amount of the enzyme, measured in fibrinolytic units (FU).

Key Takeaways

  • Nattokinase is an enzyme from fermented soybeans that researchers have studied for potential effects on blood clotting and cardiovascular function.
  • Most human studies on nattokinase are small, conducted in Japan or Asia, and show mixed results that have not been confirmed in large Western populations.
  • The enzyme may interact with blood-thinning medications, so anyone taking warfarin, aspirin, or similar drugs should discuss nattokinase with their doctor before use.
  • Eating natto as food is different from taking nattokinase supplements, and the enzyme is largely destroyed by cooking.

What the research shows so far

Studies on nattokinase have produced results that suggest potential effects, but the evidence remains limited and preliminary. Most published research comes from Japan, South Korea, and China, where natto and nattokinase are more commonly studied. Very few large, well-controlled trials have been conducted in Western populations.

Some small studies have found that nattokinase may increase fibrinolytic activity — meaning it may help break down fibrin in the blood. A few studies suggest it might support healthy blood pressure or blood viscosity (how thick the blood is). However, these studies typically involved small numbers of people, lasted only a few weeks or months, and sometimes lacked a control group for comparison. Positive findings in one study have not always been replicated in others.

No large clinical trial has shown that nattokinase prevents heart disease, stroke, or other cardiovascular events in humans. The gap between test-tube results and real-world health outcomes remains significant. Researchers have not established what dose, if any, would be needed to produce an effect in the human body, or whether that effect would be meaningful for health.

How nattokinase is different from eating natto

Natto is a whole food — fermented soybeans with a distinctive smell and sticky texture. It contains nattokinase, but also fiber, vitamins, minerals, and other compounds from the soybean itself. When you eat natto as food, you are consuming the enzyme along with everything else in the dish.

Nattokinase supplements isolate the enzyme and concentrate it into a capsule or powder. The amount of nattokinase in a supplement is much higher than what you would get from eating a serving of natto. Additionally, cooking natto or adding it to hot dishes destroys most of the enzyme, so the nattokinase content depends heavily on how the food is prepared.

If you are interested in natto for its nutritional content — protein, vitamin K2, probiotics from fermentation — eating it as food is a different choice than taking a supplement. The supplement is designed to deliver enzyme activity, not the full nutritional profile of the fermented soybean.

Potential interactions with medications

Nattokinase may interact with medications that affect blood clotting. If you take warfarin (a prescription blood thinner), aspirin, clopidogrel (Plavix), or other anticoagulants or antiplatelet drugs, nattokinase could theoretically increase the effect of these medications and raise bleeding risk. This is not proven in humans, but it is a plausible concern based on how the enzyme works.

The same caution applies if you take nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen regularly, or if you have a bleeding disorder. You should discuss nattokinase with your doctor or pharmacist before starting it, especially if you are on any medication that affects clotting or bleeding.

Nattokinase may also interact with ginger, garlic, ginkgo, or other supplements that have anticoagulant properties. Combining multiple substances that thin the blood increases the risk of bleeding without clear benefit.

What we do not know yet

The long-term safety of nattokinase supplements has not been thoroughly studied. Most research has looked at short-term use — weeks or a few months — not years of regular supplementation. We do not have clear data on whether nattokinase is safe for pregnant or nursing people, children, or people with certain health conditions.

The optimal dose is unknown. Supplements vary widely in how much nattokinase they contain and how it is measured. Without standardized dosing and large clinical trials, it is difficult to know whether a given supplement contains what the label claims or whether the amount would produce any measurable effect.

We also do not know whether nattokinase actually prevents disease in humans. Even if it does affect blood clotting in a test tube or in a small study, that does not mean it prevents heart attacks or strokes in real life. Many substances show promise in early research but fail to help people when studied in larger, more rigorous trials.

How nattokinase fits into a longevity context

Nattokinase appears in longevity discussions because cardiovascular health is a major factor in how long people live and how well they live. Blood clotting is necessary — it stops bleeding when you are injured — but excessive clotting or clots in the wrong place can cause heart attacks and strokes. The theory is that nattokinase might help maintain a healthy balance.

However, this theory remains unproven in humans. The fact that something affects a biological process in a laboratory does not mean it will improve health or extend life in a person. Many compounds that look promising in early research never translate to real-world benefit. Nattokinase is worth watching as research continues, but it is not yet established as a longevity intervention.

If you are interested in supporting cardiovascular health, the evidence is much stronger for established approaches: regular physical activity, a diet rich in vegetables and whole grains, managing stress, not smoking, and maintaining a healthy weight. These have been studied extensively and shown to reduce cardiovascular disease risk. Nattokinase might be something to explore alongside these foundations, but not instead of them.

Frequently Asked Questions

Is nattokinase the same as vitamin K2?

No. Natto contains both nattokinase (an enzyme) and vitamin K2 (a nutrient), but they are different compounds with different functions. Vitamin K2 is involved in bone and cardiovascular health and is better studied than nattokinase. You can get vitamin K2 from natto, cheese, and fermented foods without taking nattokinase as a supplement.

Can I get nattokinase from eating natto instead of taking a supplement?

You can get some nattokinase from eating natto as food, but the amount is lower than in a supplement, and cooking destroys the enzyme. If you want the concentrated enzyme effect, a supplement delivers more. If you want the nutritional benefits of natto — protein, K2, probiotics — eating it as food is a good choice regardless of nattokinase content.

What does nattokinase do in the body?

Nattokinase breaks down fibrin, a protein involved in blood clotting. In theory, this could help prevent excessive clot formation. However, this effect has been shown mainly in laboratory and animal studies, not consistently in humans. We do not yet know whether this translates to real health benefits like preventing heart disease.

Is nattokinase safe to take long-term?

Long-term safety has not been well studied in humans. Short-term use appears tolerable for most people, but we lack data on years of regular use. If you have a bleeding disorder, take blood thinners, or are pregnant or nursing, you should talk with your doctor before using nattokinase.

Why is nattokinase popular in longevity circles if the evidence is weak?

Nattokinase is popular partly because it comes from a traditional food in a culture known for longevity, and partly because early research showed interesting effects on blood clotting. However, popularity does not equal proof. Many compounds are discussed in wellness communities based on preliminary research that has not yet been confirmed in large human trials.