Nattokinase: Benefits, Side Effects, and Precautions

Nattokinase is an enzyme (protein) found in natto, a traditional Japanese dish made from fermented soybeans. Also sold as a dietary supplement to promote heart health, nattokinase side effects are generally mild, but it may increase the risk of bleeding.

Soybeans in natto are processed using the bacterium Bacillus subtilis natto. Rich in nutrients, natto contains calcium, copper, iron, magnesium, potassium, vitamin C, and zinc.

Nattokinase's purported heart-related benefits occur by increasing the activities of the following naturally occurring proteins in your body: Tissue plasminogen activator (tPA) and urokinase. Nattokinase may also directly break down fibrin, a structural component (part) of blood clots.

This article discusses what you should know about nattokinase—its potential uses, side effects, and interactions.

Uses of Nattokinase

Nattokinase may help to prevent blood clots, lower blood pressure, and have a role in treating Alzheimer's disease.

Improves Heart Health

Nattokinase may help to prevent heart attacks and improve heart health. Research shows it offers cardiovascular benefits, including:

• Lowering blood pressure: Studies show nattokinase helps to lower both systolic and diastolic blood pressure in people with hypertension (high blood pressure). This effect seems to be more pronounced in people assigned male at birth.
• Lowering cholesterol: Research shows nattokinase may lower total cholesterol, LDL cholesterol, and triglyceride levels.
• Preventing blood clots: Nattokinase has fibrinolytic and antithrombolytic properties, which may prevent blood clots from forming and potentially even dissolve blood clots.
• Slowing atherosclerosis: Nattokinase has antiplatelet and anticoagulant effects that may help clean arteries and slow the development of atherosclerosis (hardened arteries).

However, other studies have not shown such promise. A small clinical trial of nattokinase in people without cardiovascular disease did not find any significant benefits for preventing heart disease.

More research is needed before nattinokinase supplements can be recommended for heart health.

Prevents Stroke

Nattokinase may also have neuroprotective effects and may help to prevent stroke.

In addition to lowering risk factors for stroke, including hypertension and blood clots, Nattokinase is associated with a drop in von Willebrand factor (vWF) in people assigned female at birth. vWF is a naturally occurring protein, but too much of it might be linked to a higher risk of stroke. So, less vWF may lower stroke risk.

In another small study, nattokinase combined with standard of care (SOC) may help with stroke rehabilitation. After 60 days of nattokinase supplementation, participants had better control over their blood pressure and cholesterol, as well as improvements in physical activity and quality of life.

Protects Brain Health

Nattokinase shows promise as a potential therapy for Alzheimer's and other neurologic disease.

Though research is still emerging, animal studies show nattokinase can degrade amyloid fibrils, fibrous proteins that bind together and are involved in the progression of Alzheimer's and Parkinson's diseases.

Nattokinase has also been shown to decrease acetylcholinesterase activity and inflammatory markers associated with neurodegenerative diseases.

It may also help to improve brain function in people who have had strokes. Research shows nattokinase holds promise in treating post-stroke cognitive impairment. In animal studies, it was shown to promote neurogenesis by increasing blood levels of the hormone irisin. 

While these results are promising, larger, high-quality placebo-controlled trials are still needed.

What Are the Side Effects of Nattokinase?

Like many medications and herbs, side effects are possible with nattokinase.

Common Side Effects

Natto has been a traditional Japanese food for thousands of years. There were no side effects with nattokinase in several clinical trials.

Based on this information, side effects from nattokinase seem to be rare.

Severe Side Effects

There were no side effects with nattokinase in multiple clinical trials. But possible serious side effects may include:

• Serious allergic reaction: A severe allergic reaction is a possible serious side effect of any medication. Symptoms may include breathing difficulties, itchiness, and rash.
• Clot relocation: Nattokinase may work by breaking up a clot. And as a clot is breaking apart, it may relocate and get stuck somewhere else. You may have trouble breathing if the clot gets stuck in your lungs. If the clot gets stuck in your brain vessels, it may result in a stroke.
• Excessively low blood pressure: Since nattokinase may lower your blood pressure, this side effect may become excessive and severe. Symptoms of dangerously low blood pressure may include dizziness and fainting spells.
• Severe bleeding and bruising: Nattokinase may weaken your blood by breaking clots. For this reason, there's a chance of severe bleeding and bruising side effects.

If you're having a severe allergic reaction or if any of your symptoms feel life-threatening, call 911 and get medical help right away.

Precautions

Nattokinase may pose risks in the following situations:

• Severe allergic reaction: Avoid nattokinase if you have a severe allergic reaction to it or its components (parts or ingredients). You'll also want to avoid natto.
• Pregnancy and breastfeeding: There's little information on the effects and safety of nattokinase in pregnant and breastfeeding people. What's more, there seem to be limited product labels that target these people. Reach out to your healthcare provider to weigh the benefits and risks of nattokinase while pregnant or breastfeeding.
• Children: There's little information on the effects and safety of nattokinase in children. In addition, most product labels seem to target adults—not children. Discuss the benefits and risks of nattokinase with your child's healthcare provider (pediatrician).
• Adults over 65: Older adults did participate in a nattokinase study, such as a small clinical trial in people with high blood pressure. Larger, well-designed studies are necessary to assess better the effects and safety of nattokinase in older adults. Some older adults may be more sensitive to side effects from medications. For this reason, take nattokinase with caution.
• Blood conditions: Nattokinase may break up clots and thin out your blood. For this reason, your healthcare provider may recommend against nattokinase if you have certain blood conditions, such as hemophilia (bleeding condition).
  

Dosage: How Much Nattokinase Should I Take?

Nattokinase is available in many dosage forms, with capsules likely the most common.

While there are some small short-term studies on nattokinase, larger and well-designed studies are necessary. For this reason, there are no guidelines on the appropriate dosage to take nattokinase for any condition.

To take natural medications—including nattokinase—safely, inform your healthcare providers and pharmacists about any medication changes. This includes over-the-counter (OTC), herbal, natural medications, and supplements.

This can help prevent possible interactions and side effects and ensure you’re taking it appropriately.

What Happens if I Take Too Much Nattokinase?

There is limited information about nattokinase toxicity and overdoses in humans. Taking excessive amounts of nattokinase might be similar to its potentially severe side effects—but exaggerated or excessive.

If you think you're experiencing an overdose or life-threatening symptoms, get medical help immediately.

Interactions

Use caution when taking nattokinase with the following:

• Blood pressure medications: Nattokinase may lower your blood pressure. For this reason, nattokinase may have additive effects with your antihypertensive medications, such as Microzide (hydrochlorothiazide).
• Blood thinners: Nattokinase may break up clots and thin out your blood. For this reason, nattokinase may worsen bleeding and bruising side effects of blood thinners, such as Coumadin (warfarin).

It is essential to carefully read a supplement's ingredient list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications. 

How to Store Nattokinase

Since storage instructions may vary for different natural products, carefully read the directions and packaging label on the container. But in general, keep your medications tightly closed and out of the reach of children and pets, ideally locked in a cabinet or closet. Try to store your medicines in a cool and dry place.

Discard after one year or as indicated on the packaging. Avoid putting unused and expired drugs down the drain or in the toilet. Visit the FDA's website to know where and how to discard all unused and expired medicines. You can also find disposal boxes in your area.

Ask your pharmacist or healthcare provider if you have any questions about the best ways to dispose of your medications or supplements.

Similar Supplements

Nattokinase may work similarly to the supplement ginkgo, which is also promoted for its heart-healthy benefits. And while research doesn't support ginkgo's use in lowering blood pressure or stroke risk, ginkgo may cause blood-thinning side effects.

Don't take ginkgo with nattokinase until you first talk with your healthcare provider. They can help prevent possible interactions and side effects. They can also ensure that you're giving these supplements a fair trial at appropriate doses.

Sources of Nattokinase and What to Look For

There are several different sources of nattokinase.

Food Sources of Nattokinase

Nattokinase is an enzyme (protein) that's found in natto, which is fermented soybeans. Natto is a traditional Japanese food. The fermentation process involves the bacterium Bacillus subtilis natto.

Nattokinase Supplements

Nattokinase is available in a variety of forms, including capsules and tablets. If you have difficulties swallowing pills, nattokinase might also be available in other dosage forms, such as powder. There may also be vegan and vegetarian options.

The specific product you choose will depend on your preference and what you hope to get in terms of effects. Each product may work a bit differently depending on the form. So, it's important to follow your healthcare provider's recommendations or label directions.

Summary

Nattokinase is an enzyme (protein) that's found in natto, which is fermented soybeans. Natto is a traditional Japanese food, and the fermentation process involves the bacterium Bacillus subtilis natto.

Nattokinase may have potential uses in heart-related conditions, such as high blood pressure, high cholesterol levels, and stroke. And in reference to one study, there were no side effects with nattokinase in several clinical trials.

However, side effects and medication interactions are possible based on how nattokinase might work. More high-quality research with more extensive, well-designed clinical trials is necessary to assess nattokinase effectiveness and safety. Before you take nattokinase, contact your pharmacist or healthcare provider to help you safely achieve your health goals.