The Health Benefits of Nattokinase

This Soybean-derived enzyme may treat certain cardiovascular diseases

Nattokinase fermented soybeans

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Nattokinase is an enzyme extracted from natto, a Japanese food made from fermented soybeans. Natto is a popular breakfast dish in Japan known for its strong, cheese-like smell and sticky consistency. It is produced by adding the bacterium Bacillus subtilis natto to boiled soybeans and leaving until fermented.

The only source of nattokinase is from natto and it can only be produced by this specific fermentation process. The extracted enzyme is manufactured into capsules and tablets, although it can also be found in powdered form in Japan.

Natto has long been used in folk medicine to treat cardiovascular diseases; nattokinase is believed to possess the same properties. While generally considered safe and tolerable, nattokinase may cause side effects and interact with certain medications.

Health Benefits

In alternative medicine, nattokinase is believed to benefit people with heart and vascular diseases, in part by breaking down blood clots that can impede circulation. Among the conditions nattokinase is purported to prevent or treat are:

To date, there are few studies that strongly support these claims. That is not to say that promising research doesn't exist; it is simply that most of the studies are small and often poorly designed. Here are a few worth considering.

Deep Vein Thrombosis

Deep vein thrombosis (DVT) is the medical term used to describe a blood clot in a deep vein, usually a leg. It tends to affect older people who are obese and have underlying circulatory problems.

A 2015 study published in Scientific Reports reported that a single 100-milligram (mg) dose of nattokinase, taken orally, was able to break down fibrin (a protein involved in blood clotting) more effectively than a placebo. It also acted as a potent anticoagulant (blood thinner), reducing the concentration of a blood-clotting protein known as Factor VIII.

The research suggests that nattokinase supplements may provide protection against DVT by preventing the formation of clots.

While the results are promising, the conclusions are limited by the small size of the study. Moreover, the participants recruited for research (12 healthy, young men) are among the least likely to develop DVT. Further research would be needed to see if the same results can be replicated in higher-risk groups.

Atherosclerosis

Atherosclerosis, also referred to as the "hardening of arteries," is caused by the buildup of fatty plaques on the arterial walls.

A 2018 study from China, involving 76 adults with atherosclerosis, reported that participants given a 150-mg daily dose of nattokinase over 26 weeks experienced a 36.6% reduction in arterial plaque compared to only 11.5% in those given a 20-mg dose of simvastatin. Additionally, nattokinase increased the level of "good" HDL cholesterol where simvastatin didn't.

On the flip side, simvastatin was far more effective in reducing the total cholesterol, triglycerides, and "bad" LDL cholesterol, reductions of which are vital to the prevention of cardiovascular disease.

As contradictory as these findings seem, they highlight how little scientists understand the mechanism of action of nattokinase. Further research is needed to identify how nattokinase works and its implication in preventing heart attacks, stroke, and other conditions related to atherosclerosis.

Stroke

Cardiovascular disease and brain health are closely linked. In recent years, there have been suggestions that nattokinase may have neuroprotective properties that halt disease progression in people with ischemic stroke.

A 2015 study in the journal Stroke reported that nattokinase, given by injection, may the improve blood flow to the brain following a stroke. By injecting lab mice with three doses of nattokinase prior to an induced stroke, the scientists found that smaller vessels in the brain remained unblocked, limiting the spread of tissue damage.

The ability to break down fibrin (referred to as fibrinolysis) makes nattokinase an ideal candidate for research—not only with respect to stroke but to other conditions influenced by fibrinolysis impairment, including Alzheimer's disease.

Possible Side Effects

As a derivative of nattō, a food eaten for centuries in Japan, nattokinase is presumed to be safe, although there is little data as to its long-term effect. That doesn't mean that it is without concerns.

Because nattokinase can influence blood circulation and chemistry, it should be used with caution in certain groups, namely:

  • People with bleeding disorders, such as hemophilia, in whom nattokinase may make symptoms worse
  • People who take blood thinners, including warfarin, in whom nattokinase may promote bleeding and easy bruising
  • People with low blood pressure, also known as hypotension, in whom nattokinase may cause lightheadedness, headaches, dizziness, and fainting
  • People on antihypertensive drugs, like ACE inhibitors and calcium channel blockers, in whom nattokinase may intensify the drug's effect, triggering hypotension

Nattokinase should also be stopped no less than two weeks prior to a scheduled surgery to reduce the risk of excessive bleeding.

Due to the lack of research, nattokinase should be not be used in children or during pregnancy or breastfeeding.

Dosage and Preparation

Nattokinase is found almost exclusively in the United States in capsule or tablet form. Doses are often described in fibrin units (FU), with 2,000 FU translating to roughly 100 milligrams and 3,000 FU translating to 150 milligrams.

There are no universal guidelines for the appropriate use of nattokinase. Doses of up to 3,000 FU have been used safely for up to 26 weeks, although most manufacturers recommend no more than 2,000 FU per day.

In addition to supplements, you can also obtain nattokinase by adding natto to your diet. There are small producers in the United States who ship fresh natto directly to consumers and health food stores. You can also make your own by purchasing Bacillus subtilis natto spores online.

Natto offers some advantage over nattokinase supplements in that it is rich in probiotic bacteria beneficial to gut health.

Natto is also high in fiber and delivers over 20% of the recommended daily intake of iron, magnesium, calcium, vitamin C, and potassium.

On the downside, a one-cup serving of natto has around 371 calories. That is not exceptionally high but accounts for nearly one-fifth of a 2,000-calorie diet. Unless you watch your portions carefully, you could very well end up gaining weight on nattō.

What to Look For

Because dietary supplements are not strictly regulated in the United States, the quality can vary from one brand to the next.

To ensure quality and safety, choose brands that have been tested by an independent certifying body like the U.S. Pharmacopeia (USP), ConsumerLab, or NSF International. The certification does not mean that the product is effective but that it simply contains the ingredients and amounts listed on the product label.

If purchasing Bacillus subtilis natto spores, opt for those that are 100% organic and sold through a reliable third-party retailer. You should also that check that Bacillus subtilis or Bacillus subtilis natto is printed on the product label to ensure you are getting the unadulterated product.

Other Questions

How do you make natto?

Natto has been consumed for centuries in Japan, but it was only in the early part of the 20th century that Bacillus subtilis was used as the fermenting agent.

To make natto at home, you need to ensure that all your utensils, bowls, and equipment are properly sterilized by dipping them in a pot of boiling water. The process of making fresh natto involves 10 steps:

  1. Wash and soak one pound of dried soybeans for 24 hours.
  2. Boil or steam the beans for three to six hours until soft.
  3. Drain and transfer the soybeans into a sterilized bowl.
  4. Mix one teaspoon of Bacillus subtilis powder with two tablespoons of sterilized water
  5. Pour the spore mixture over the beans and stir.
  6. Transfer the beans to a sterilized dish, spreading them no thicker than one inch.
  7. Place a piece of cheesecloth over the dish and secure with a rubber band.
  8. Place the dish in the oven with the oven light turned on but the temperature turned off. The temperature should be kept between 100o and 115o F.
  9. Leave the soybeans in the oven 22 to 24 hours, checking the temperature occasionally.
  10. Remove the dish from the oven, and place it in the refrigerator overnight with the cheesecloth left on. Stir before eating.

Natto can be stored for up to one week in the refrigerator and up to two months in the freezer.

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Article Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Ren NN, Chen HJ, Li Y, et al. A clinical study on the effect of nattokinase on carotid artery atherosclerosis and hyperlipidaemia. Zhonghua Yi Xue Za Zhi. 2017 Jul 11;97(26):2038-2042. doi:10.3760/cma.j.issn.0376-2491.2017.26.005.

  2. Bell V, Ferrão J, Fernandes T. Nutritional Guidelines and Fermented Food Frameworks. Foods. 2017 Aug;6(8):65. doi:10.3390/foods6080065.

Additional Reading

  • Ahn YJ, Kim MH, Kim J, et al. Abstract W P262: Neuroprotective Effect of Nattokinase Mediated by Inhibition of Platelet Aggregation and Thrombosis in Photothrombotic Stroke. Stroke. 2015;46(Suppl 1):AWP262.

  • Kurosawa Y, Nirengi S, Homma T, et al. A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles. Sci Rep. 2015;5:11601. doi:10.1038/srep11601.

  • U.S. Department of Agriculture. Basic Report: 16113, Natto. National Nutrient Database for Standard Reference Legacy Release. Washington, D.C.; April 2018.