Nattokinase and K2 Together: Heart Health's Dynamic Duo

What do Japanese folklore and fermented soybeans have to do with your heart health? It turns out quite a lot actually. If you haven’t heard of the connection between nattokinase and vitamin K2, you are in for an interesting story. While this dynamic duo doesn’t work together directly, their synergy supports your body in a number of ways. You will learn how both nattokinase and vitamin K2 work in the body to support heart health and why you may want to add them to your health routine.

What Are Nattokinase and Vitamin K2?

Before we get into the benefits of these two supplements, let’s learn a little about each one.

Nattokinase: The Enzyme Star from Fermented Soybeans

There are a few different stories that tell how natto came about, but the most famous version revolves around the 11th century samurai Minamoto no Yoshiie.¹ Legend has it that Yoshiie’s troops were interrupted while boiling soybeans to feed their horses. The beans were hastily put into straw bags and left for a few days. When the bags were open, the now fermented soy beans were discovered and surprisingly enjoyed. This is just one version of how natto was discovered, but the truth is that it has been a staple of Japanese cuisine for hundreds of years.

Historically natto has been an important source of dietary protein. Since it is fermented it is perfect for long-term storage and consumption over long periods of time such as traveling or military expeditions. The unique flavor, sticky texture and strong smell make it an acquired taste. Traditionally it is served over hot rice with soy sauce and mustard, but it has found its way into a variety of dishes from soup to sushi. With modern production methods natto is widely available for easy use.

So what makes natto special? It comes down to its powerful “fibrinolytic” properties thanks to an enzyme called nattokinase. Blood clots are held together by a fibrous protein in the blood called fibrin. Created by the Bacillus subtilis bacteria during fermentation, nattokinase dissolves fibrin.² This fibrinolytic activity is what has attracted the attention of many interested in maintaining their cardiovascular health.

Vitamin K2: The Overlooked Nutrient That Directs Calcium Traffic

While there are several different forms of vitamin K, there are two forms that are commonly found in our food: vitamin K1 and vitamin K2. The vitamin K group are fat-soluble vitamins that support calcium regulation in the body. Vitamin K1 (known as phylloquinone) is one form of vitamin K typically found in leafy green vegetables. Vitamin K2 (known as menaquinone) is another form of vitamin K typically found in fermented foods (like natto) and meat.

While both are part of the vitamin K group, they have different jobs in the body. Vitamin K1 mainly supports blood clotting. Vitamin K2 plays a smaller part in blood clotting but has a bigger part in bone and heart health. Further complicating matters there are two forms of vitamin K2: MK-4 (menaquinone-4) and MK-7 (menaquinone-7). MK-4 is absorbed quickly while MK-7 stays in the bloodstream longer so it can be absorbed over time.

Global Perspectives: Cultural Nutrient Traditions

For centuries natto has been seen as a healthy food in Japan. Natto even made an appearance as the featured ingredient in the classic IRON CHEF TV show. It can be used in a number of different dishes to add flavor and protein. Giving natto a vigorous stir helps increase stickiness for a boost in texture. While the benefits of eating natto have been long known in Japan, it is still an acquired taste.

Across Europe, vitamin K2 rich foods such as cheese, sauerkraut and kefir have been a dietary staple. Cheeses such as Gouda, edam, Jarlsberg, Camembert and Muenster are known to be rich in vitamin K2. Bacteria in these foods produce vitamin K2 as part of the fermenting process.

By regularly including these fermented foods in their diets, both groups have been reaping the benefits of nattokinase and vitamin K2 for hundreds of years. A modern Western diet is often lacking in fermented foods, making the case for supplementation that much stronger.

The Heart Health Benefits: Two Different Approaches

So how can nattokinase and vitamin K2 support your cardiovascular health?

Nattokinase Benefits for Circulation

As previously mentioned nattokinase dissolves fibrin, the main protein that forms blood clots helping to support healthy blood flow. Nattokinase supports fibrinolytic activity by breaking apart fibrin strands that hold blood clots together. Fibrin creates long, sticky threads that form a mesh to trap red blood cells and platelets at an injury site. It’s the fibrin that creates a sort of internal gauze pad to help stop bleeding. Nattokinase supports healthy blood flow by breaking down blood clots and reducing excess fibrin. Research shows that nattokinase may also offer blood pressure support.³

Vitamin K2 Benefits for Calcium Balance

When most people think about calcium in the body they instantly think about bones. But calcium actually ends up in other places, sometimes with negative effects. Vitamin K2 supports directing calcium to the places it is needed and away from the places it shouldn't be. By activating a special protein called osteocalcin vitamin K2 helps calcium bind to your bone matrix where it is needed.⁴ Studies suggest that vitamin K2 may support healthy vascular elasticity.⁵ Vascular elasticity is important because it allows blood vessels (including the aorta) to stretch and retract with each heartbeat.

The Science of Blood Clotting and Prevention

Stopping bleeding after an injury requires a microscopic team effort. First platelets stick together at the wound site to initially plug the hole. Clotting factors already in the blood activate signaling other actions leading to fibrin production. Fibrin weaves into the platelet plug to seal the wound while also collecting additional platelets and red blood cells to make a stronger plug. But stopping blood flow isn’t always a good thing. Nattokinase’s effect on breaking down blood clots while helping prevent new ones helps support healthy blood flow. Likewise vitamin K2 supports healthy blood flow by keeping calcium out of your arteries and in your bones where it belongs.

The Big Question: Friends or Foes?

Are nattokinase and vitamin K2 allies or do they work against each other? The answer is: it's complicated.

Do These Supplements Cancel Each Other Out?

While it might seem like nattokinase and vitamin K2 would cancel each other out, they are actually on the same side of balancing good health. Think of it like a football team. There is an offense and a defense, but they both work toward the goal of winning the game. They both have different effects on blood clotting but work in different ways. Blood will still clot when necessary, but won’t be forced to clot otherwise. On the other hand excess fibrin is dissolved so unnecessary clots don’t form.

Research on Their Complementary Nature

Natto is actually a vitamin K2-rich food, so it is already paired with nattokinase. One large-scale nattokinase study found that vitamin K2 had a synergetic effect on lipid levels.⁶ While there are many studies on the effects of both nattokinase and vitamin K2, more research needs to be done on how they work together on a microbiological level. Both support cardiovascular health by helping maintain blood circulation.

How They Actually Work Together

Your body’s self-sealing defense mechanism against wounds is actually pretty amazing. But what is more amazing is that the body is able to regulate both keeping blood flowing smoothly and stopping it completely. The complementary relationship between nattokinase and vitamin K2 is more synergistic than direct.

Who Should Consider This Dynamic Duo

So now that you know a bit more about what nattokinase and vitamin K2 can offer, how do you know if they should be a part of your healthy lifestyle?

Age and Health Considerations

Nattokinase

Most healthy adults up to age 65 respond well to a nattokinase supplement. Adults over age 65 need to be aware of potential side effects such as bleeding, especially for those taking medications that inhibit clotting.* Currently there is not enough research around the effects of nattokinase on those who are pregnant or breastfeeding, so people who fall into those categories should avoid taking a nattokinase supplement. Children should also avoid nattokinase supplements unless otherwise directed by a healthcare provider.**

Vitamin K2

In general everyone benefits from vitamin K2, although not always necessarily from a supplement form. The recommended daily intake for vitamin K2 varies, so make sure to consult with your healthcare provider for guidance.⁷** Those who are concerned about bone quality or vascular health may want to talk to their healthcare provider about vitamin K2.

Lifestyle Factors and Deficiency Risks

Nattokinase

Those with a sedentary lifestyle may be more prone to circulation issues, while an active lifestyle promotes healthy circulation. Eating a diet that does not include natto (or other fermented soy products) severely limits nattokinase intake. Since nattokinase is not an essential nutrient, there is no recognized deficiency.*

Vitamin K2

Those with a sedentary lifestyle are more prone to bone health and cardiovascular issues, while an active lifestyle supports healthy bones and heart. Dietary sources of K2 vitamin may not be enough depending on individual circumstances, leading to a deficiency. High-stress lifestyles may lead to poor dietary choices, further reducing vitamin K2 availability. Vitamin K2 deficiency signs may surface as blood clotting issues, poor bone health or cardiovascular issues.*

Important Safety Considerations

It is always important to consult with your healthcare provider whenever you are thinking of adding a supplement to your healthcare routine. Here are a few other points to keep in mind when talking to your healthcare provider.**

When to Avoid These Supplements

Take note if you fall into any of the following situations so you can make the best choice for yourself:

Nattokinase

• Anyone taking anticoagulant or antiplatelet medications
• Anyone scheduled for surgery
• A history of blood clot-centered health issues
• Low blood pressure
• Pregnant or breastfeeding
• An allergy to natto

Vitamin K2

• Anyone taking vitamin K antagonist blood thinners
• Anyone with severe kidney issues
• Anyone with liver issues
• An allergy to vitamin K2

Your healthcare provider is your best resource for information about adding nattokinase or vitamin K2 for your unique health situation.**

Working with Healthcare Providers

Everyone’s health needs are different which is why it is best to speak with your healthcare provider when considering any new supplement. Make sure to talk about the following topics:

• Current medications and supplements. Don’t leave anything out. Include any over-the-counter medications.
• Share your complete medical history, especially any issues regarding bleeding or blood clotting.
• Ask about any potential interactions between your current medications and any potential new supplements. Supplements can amplify certain medicinal effects, so this is important.
• Dosage can vary based on your personal needs, so ask about specific recommendations. Include any situations that may affect your needs (like pregnancy).
• Be honest about your goals and what results you’d like to see from taking a supplement. Your individual needs may require a broader approach or a more targeted solution.
• Set a followup appointment. Once you start on a new health regimen make sure to routinely evaluate the results so any adjustments can be made. If something doesn’t seem right, now is the time to discuss it.

Your healthcare provider is your healthy living partner, so make sure to work with them along your journey.

Finding Quality Supplements

If you’ve decided that a nattokinase or vitamin K2 supplement is in your best interest, you want to make sure you get the best.

What Makes a Good Nattokinase Supplement

When shopping for a high-quality nattokinase supplement make sure to look for the following:

• Verified enzyme activity should be clearly stated in fibrinolytic units (FU). This is how dosage is determined.
• For nattokinase processing methods matter. Following precise fermentation guidelines allows for optimal nattokinase yield. Modern purification methods drastically reduce impurities. Using the spray drying method helps prevent degradation while improving storage stability.

Choosing the Right K2 Supplement

When shopping for a high-quality vitamin K2 supplement you need to be aware that there are two main forms available: MK-4 (menaquinone-4) and MK-7 (menaquinone-7).

• MK-4 is quickly absorbed by tissue but has a short half-life in the bloodstream. Doses may need to be more frequent.
• MK-7 has a longer half-life in the bloodstream for a more sustained presence. It may be more convenient with only one dose needed per day.

Some supplements contain MK-4 and MK-7 to leverage the benefits of both forms.

When shopping for any supplement looks for these signs:

• Third-party testing certifications and seals for quality and purity.
• High-quality ingredients with sourcing information. Stay away from artificial ingredients or unnecessary additives.
• Clear and complete labeling. All ingredients should be noted as active or inactive.
• Positive reviews by real people.

At Swanson our products meet the highest quality standards backed by third-party lab testing for purity and potency you can trust. Our manufacturing facilities are Good Manufacturing Practice (GMP) certified to ensure that quality.

How to Take Them for Best Results

In order to get the most out of your nattokinase or Vitamin K2 supplement here are a few best practices.

Timing and Dosage Guidelines

Nattokinase can be taken any time of the day, but we suggest taking it at the same time each day to maintain a steady amount in your system. Suggested daily dosage is 100 mg (2,000 fibrinolytic units).

Since vitamin K2 is fat soluble it does best when taken with a meal containing a form of fat. It should be taken at the same time each day to maintain steady blood levels. MK-7 usually only needs to be taken once a day, while MK-4 may need multiple doses throughout the day.

Complementary Nutrients

As mentioned earlier nattokinase and vitamin K2 have a synergistic relationship. Other nutrients may also support your health goals. For example omega-3 fatty acids support cardiovascular and heart health complementing nattokinase. Vitamin D supports bone health and may have a synergistic effect with vitamin K2. Magnesium promotes healthy blood pressure levels and is essential for bone health, making it complementary for both nattokinase and vitamin K2.

Foods can also complement nattokinase and vitamin K2. Natto contains both nattokinase and vitamin K2 (in MK-7 form). Cheeses like Gouda and Muenster are good sources of vitamin K2. Both sauerkraut and kimchi have small amounts of vitamin K2.

Making Natto More Palatable

Natto may be good for you but it is an acquired taste. The simplest way to eat natto is over steamed rice with a little soy sauce. There are endless recipe variations of natto and rice, so look for one that has familiar ingredients you enjoy and try it. You can also try spreading natto over toast then topped with cheese and toasted again until the cheese melts. For sushi lovers make a simple sushi roll with natto as the main component. You can also add natto to fried rice toward the end of cooking so that it mixes all together and dilutes the taste. Of course if you just can’t stand natto, nattokinase and vitamin K2 supplements are readily available.

Common Questions About Nattokinase and K2

Here are some of the more common questions we’ve heard when it comes to nattokinase and vitamin K2.

Food vs. Supplements: Finding Balance

Should you eat nutrient rich foods or just take a supplement? It depends on the question.

Question: "Can I get enough from food alone?"

Answer: If you eat natto regularly you can get significant amounts of both nattokinase and vitamin K2. Otherwise the best source of both nutrients are supplements. Foods such as cheeses, sauerkraut, kimchi, beef liver and eel all contain vitamin K2 in varying amounts. While it is possible to reach the recommended daily amount of vitamin K2 through diet, it isn’t always convenient or may be complicated due to dietary restrictions. A supplement is a quick and easy vitamin K2 source.

Question: "How long before I notice the benefits?"

Answer: Limited research suggests nattokinase begins to influence blood clotting factors within a few hours of ingestion. Vitamin K2 takes several weeks to several months to begin showing signs of bone health and arterial support.

Question: "Should I cycle these supplements?"

Answer: Cycling is not necessary for nattokinase and vitamin K2. People have been eating natto daily for hundreds of years with no ill effects. Both of these nutrients give the most support when taken on a regular basis.**

Practical Usage Questions

Here are a few common questions from the practical side of using nattokinase and vitamin K2. 

Question: "Are there any alternatives if I can't take one of them?"

Answer: An alternative to nattokinase is lumbrokinase, a group of highly stable fibrinolytic enzymes that may have cardiovascular benefits. While not a direct substitute to vitamin K2, vitamin K1 does offer some of the same benefits.

Question: "What about natto's taste? Do I have to eat it?"

Answer: No, you do not have to eat natto to enjoy the benefits of nattokinase and vitamin K2. Supplements are widely available for either nutrient.

Question: "Can I take them if I'm pregnant or nursing?"

Answer: There is not enough research to say whether nattokinase supplements are safe to use while pregnant or nursing, so is it best to avoid them. Vitamin K2 is a vital part of both maternal and fetal health, but it is strongly suggested to consult with your healthcare provider before taking any supplements when pregnant or nursing.**

The Bigger Picture: Beyond Supplements

Consider taking a holistic approach to heart health rather than focusing on one certain area. Eat a healthy diet with plenty of fruits, vegetables, whole grains, healthy fats and lean proteins. Make sure to stay hydrated and cut out the processed foods. Try to exercise for at least an hour each week. Aerobic exercise like walking, swimming or cycling work well. Maintain a healthy weight and get plenty of sleep. Mental health is also important so if stress is an issue try mediation, yoga or a relaxing hobby. Make sure to track your own health. There are a number of easy ways to track heart rate, blood pressure, blood sugar, stress levels and more so you can use real data for your benefit. Talk to your healthcare provider about your goals and ask which lifestyle changes or supplements can help you reach them.

Heart Health Partners, Not Opponents

As you can see the synergistic relationship between nattokinase or vitamin K2 supports different body systems but in ways that benefit both. Nattokinase supports healthy blood flow while vitamin K2 supports vascular health. Like many systems in the body, there must be balance for optimum health. By both being prepared to create blood clots in an emergency while also not creating them unnecessarily the body is ready for either scenario.

Before embarking on a new supplement regimen make sure to talk to your healthcare provider first. Be sure to understand all the supplement benefits but also any potential drawbacks or interactions. Being fully informed about not only your health but also your potential options ensures you are making the right decisions for your unique situation. You may also find out that there are other options better suited to your health regimen, so don’t be afraid to ask questions. You are your own best health advocate, so make the most of it every day!

You be well, now.

Swanson

 

 

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

 

**Contact your healthcare professional for advice if you take any other medications.

 

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5. Cees Vermeer and Hogne Vik. Vascul Dis Ther, 5. Accessed 13 Jun 2025. Read source.

6. Chen H, et al. Front Cardiovasc Med. 2022 Aug 22;9:964977. Read source.

7. National Institutes of Health (NIH). Vitamin K Fact Sheet for Health Professionals. Accessed 13 Jun 2025. Read source.