SupplementsDigestive EnzymesNattokinase

Nattokinase

2,000 fibrinolytic units per capsule

An enzyme from a sticky Japanese soybean dish, and one of the few supplements that acts directly on how your blood clots, which is exactly why it needs care.

Get a protocol
A small nattokinase capsule
Builds up
Hours to weeks
In your body
Not known
Per 1 capsule
200 mg
30-day supply
$7.50One capsule a day, plus packing and delivery

What is nattokinase?

Natto is a traditional Japanese food made by fermenting soybeans with a bacterium called Bacillus subtilis. People have eaten it for over a thousand years. It's famous for its slimy strings and strong smell.

In 1980, a Japanese researcher named Hiroyuki Sumi found that natto could dissolve fibrin, the mesh that holds a blood clot together. He pulled out the enzyme responsible and called it nattokinase.

Ours holds 200 mg, with an activity of 2,000 fibrinolytic units. That's the measure of how strongly it breaks down fibrin, and it's the same number most human studies used. Because it comes from soybean fermentation, the supplier's label lists soy as an allergen.

What it does

  • CirculationSupports healthy blood flow.
  • Clotting balanceSupports the body's normal breakdown of fibrin.
  • Blood pressureHelps maintain blood pressure already in the healthy range.

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure or prevent any disease.

The full guide · 16 min readNattokinase benefits and side effects: what the evidence showsWhich form, how much, when to take it, and whether it's worth it, with the studies behind each answer.

What people take it for

How long it takes

Clotting tests shift within hours of one capsule. Slower changes, like fibrinogen, kept falling over 2 months of daily use. Blood pressure studies ran for 8 weeks.

Nattokinase in your blood after a capsule, from one small studyTypical pattern
Highest at about 13 hours
Still raised at 24 hours
048 hours
  1. 2 to 8 hoursClotting tests shift, staying within the normal range
  2. About 13 hoursHighest level in your blood, in one small study
  3. 8 weeks to 2 monthsHow long the blood pressure and fibrinogen studies ran

How long it stays in your body

There's no clean number. Some sites quote 8 to 12 hours, but we couldn't find a study behind that. One small study found it peaked at about 13 hours and was still raised at 24.

What's in a capsule

One capsule holds 200 mg, with 2,000 fibrinolytic units of activity, the same activity used in the blood pressure studies and the 3-year study. Some clotting studies used double.

An enzyme that survives the trip

Enzymes are proteins, and taking proteins apart is what your gut does all day. Nattokinase seems to be a stubborn exception. It's stable enough in your gut that researchers have measured it in human blood after a capsule. How much gets through is still unknown, and small studies are all we have.

It works in more than one way. It breaks down fibrin directly, and it also helps switch on the clot-breaking system your body already has. After one capsule in healthy young men, D-dimer went up, factor VIII went down and aPTT, a clotting time test, got longer. All of it stayed inside the normal range.

That's also the reason for caution. One person already on aspirin, with tiny old bleeds in the brain, had a serious brain bleed after a week on nattokinase. That's one case, and we can't say what caused it. But it's why it doesn't mix casually with anything else that thins your blood. One more thing: natto the food is rich in vitamin K2. Our capsule's label doesn't list any.

Read the full guide to nattokinase

What it interacts with

Goes well with

Side effects

  • Human studies reported few side effects, though most were small and short.
  • Bleeding is the one to watch. If you get unusual bruising, nosebleeds, black stools or a sudden bad headache, stop and get medical help.

Check first if

  • Blood thinners, aspirin or a bleeding disorder: talk to your doctor before you start.
  • History of stroke or bleeding in the brain: don't start without your doctor's say.
  • Upcoming surgery: tell your care team first.
  • Low blood pressure: it may lower it further, so ask first.
  • Soy allergy: the label lists soy as an allergen, so we'd avoid it.
  • Pregnancy or breastfeeding: we found no good safety data, so check with your doctor.
  • Liver or kidney disease: we found no good safety data, so ask your doctor.

The blood tests that go with it

Work it out

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Supplementation

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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.

Want it more precise? Get the app.

A page can only tell you about Nattokinase. The app tells you about you: whether it fits, when to take it, and whether it's working.

  • Checked against your blood work and everything you already take
  • On your daily timeline, around your sleep, training and meals
  • Followed over time, so you can see what moved
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Questions

What is nattokinase good for?

People take it for circulation, blood pressure and clotting balance. Short studies look positive for blood pressure, but a 3-year study in healthy older adults found no effect.

How long does nattokinase take to work?

Clotting tests shift within hours, but you won't feel that. Blood pressure studies looked at 8 weeks, and fibrinogen kept falling over 2 months.

What are the side effects of nattokinase?

Studies reported few. Bleeding is the main concern, especially if you take something else that thins your blood. Watch for unusual bruising, nosebleeds or black stools.

Who should not take nattokinase?

Anyone on blood thinners or aspirin, with a bleeding disorder or history of a brain bleed, or with surgery coming up should talk to their doctor first. Avoid it if you have a soy allergy.

What does nattokinase interact with?

Blood thinners and aspirin most of all, and possibly blood pressure medicines. It can also shift clotting blood tests.

Is nattokinase a blood thinner?

It acts on clotting, but it isn't a medicine and it's no substitute for one. Never swap a prescribed blood thinner for it.

Does nattokinase dissolve blood clots?

It breaks down fibrin in the lab and shifts clot markers in people, but that's not the same as clearing a clot in your body. If you think you might have a clot, get emergency care.

Can I take nattokinase every day?

Studies gave it daily, and one ran for about 3 years in older adults at low heart risk, with no changes in their lab results. If your risks are different, or you take anything that affects clotting, check first.

What is the half-life of nattokinase?

Nobody has a clean number. One small study found it peaked at about 13 hours and was still raised at 24.

Is eating natto the same?

Not quite. The food also contains vitamin K2, which our capsule's label doesn't list. It's a fine food, but check with your doctor if you take warfarin.

Sources
  1. Weng Y et al. Nattokinase: an oral antithrombotic agent for the prevention of cardiovascular disease. Int J Mol Sci, 2017.
  2. Hodis HN et al. Nattokinase atherothrombotic prevention study. Clin Hemorheol Microcirc, 2021.
  3. Kim JY et al. Effects of nattokinase on blood pressure. Hypertens Res, 2008.
  4. Jensen GS et al. Consumption of nattokinase is associated with reduced blood pressure and von Willebrand factor. Integr Blood Press Control, 2016.
  5. Hsia CH et al. Nattokinase decreases plasma levels of fibrinogen, factor VII, and factor VIII in human subjects. Nutr Res, 2009.
  6. Kurosawa Y et al. A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles. Sci Rep, 2015.
  7. Yoo HJ et al. The effects of nattokinase supplementation on closure time, prothrombin time and activated partial thromboplastin time. Food Funct, 2019.
  8. Ero MP et al. A pilot study on the serum pharmacokinetics of nattokinase in humans. Altern Ther Health Med, 2013.
  9. Dabbagh F et al. Nattokinase: production and application. Appl Microbiol Biotechnol, 2014.
  10. Chang YY et al. Cerebellar hemorrhage provoked by combined use of nattokinase and aspirin. Intern Med, 2008.
  11. Ren NN et al. A clinical study on the effect of nattokinase on carotid artery atherosclerosis and hyperlipidaemia. Zhonghua Yi Xue Za Zhi, 2017.
  12. Afzaal M et al. Nutritional health perspective of natto. Biochem Res Int, 2022.

Written by LifeFrom from these sources, and not yet reviewed by a clinician. Talk to your doctor before starting a supplement.

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