How much nattokinase per day?

The most-studied nattokinase dose is 2,000 fibrinolytic units a day — one capsule — but the largest study ever run on the enzyme used more than five times that.

That gap is the entire problem. Human research spans the standard 2,000 FU daily capsule up to 10,800 FU per day, and the right number depends far less on your body weight than on which outcome you are trying to move.

Here is what each dose has actually been shown to do, when to take it, and where the ceiling sits.

Table of Contents

1. The Short Answer: 2,000 FU Per Day
2. Why FU Matters More Than Milligrams
3. What 2,000 FU a Day Has Been Shown to Do
4. When the Research Points to a Higher Dose
5. The Three-Year Trial That Found Nothing
6. When to Take Your Daily Dose
7. Upper Limits, and Who Should Take None
8. BioAbsorb Nattokinase Enzyme: 2,000 FU, Verified Per Batch
9. Frequently Asked Questions
10. Conclusion
11. Research References

1. The Short Answer: 2,000 FU Per Day

For most adults taking nattokinase for general cardiovascular support, the answer is 2,000 fibrinolytic units once daily — one standard capsule, equivalent to roughly 100 mg of enzyme. This is the dose used in the majority of published human trials, and the reference dose in the Drugs.com professional monograph [9], which lists 100 mg daily for 8 weeks as the pattern used in fibrinolytic and blood pressure research.

It is worth being clear about why 2,000 FU became the standard: it was the dose the early Japanese and Korean trials selected, and later studies followed. It is not a figure derived from dose-ranging work, and no regulator has set a recommended daily intake. Understanding how nattokinase works at the enzyme level helps explain why a single fixed dose has held up as long as it has.

Body weight does not feature in the published protocols. The 2008 randomised trial gave the same 2,000 FU capsule to participants aged 20 to 80 [1], without adjusting for size. Nattokinase is dosed by enzyme activity, not by kilogram.

2. Why FU Matters More Than Milligrams

Nattokinase labels carry two numbers, and most shoppers read the wrong one. Milligrams tell you how much enzyme powder is in the capsule. Fibrinolytic units tell you how much fibrin-dissolving activity that powder actually has — and two capsules with identical milligram counts can differ substantially in potency.

The conversion most products use is approximately 2,000 FU per 100 mg. The 2016 North American trial encapsulated its enzyme at 100 mg per capsule standardised to at least 2,000 FU [6], and the 10,800 FU used in the largest study corresponds to roughly 540 mg of the same material.

Applying that same ratio to the doses used across the research gives the following rough milligram equivalents. Only the FU figures come from the trials themselves; the milligram column is calculated from the 2,000 FU per 100 mg standard above.

• 2,000 FU ≈ 100 mg — the standard daily capsule
• 3,600 FU ≈ 180 mg — tested and found ineffective for arterial endpoints
• 4,000 FU ≈ 200 mg — the dose that lowered clotting factors over 2 months
• 10,800 FU ≈ 540 mg — the dose that moved plaque and lipid markers over 12 months

If a label states milligrams only, you cannot tell what you are taking. That ambiguity is the practical reason to compare products on FU, a point covered in more depth in our full nattokinase dosage guide.

3. What 2,000 FU a Day Has Been Shown to Do

The strongest evidence at the standard dose concerns blood pressure. A randomised, double-blind, placebo-controlled trial enrolled 86 adults with untreated systolic pressure of 130–159 mmHg; among the 73 who completed 8 weeks, the nattokinase group ended 5.55 mmHg lower in systolic and 2.84 mmHg lower in diastolic pressure [1] than controls. A later meta-analysis pooling randomised trials put the average diastolic effect at 2.32 mmHg below placebo [7], with no notable adverse events reported across the included studies.

The second finding at this dose is short-lived and biochemical. In a double-blind crossover study of 12 healthy men, a single 2,000 FU dose shifted D-dimer, Factor VIII activity and clotting time across the 2-to-8-hour window [4]. Every change stayed inside the normal reference range, which is why a daily dose is a maintenance strategy rather than something you feel.

Sustained effects on clotting factors have been recorded at double the standard dose. An open-label trial in 45 adults across healthy, cardiovascular-risk and dialysis groups used two 2,000 FU capsules daily — 4,000 FU — for two months, and reported fibrinogen down 7–10%, Factor VII down 7–14% and Factor VIII down 17–19% [5], with no notable adverse events.

4. When the Research Points to a Higher Dose

If the goal is arterial or lipid endpoints rather than blood pressure, the standard capsule appears to be under the threshold. A 12-month study of 1,062 participants averaging 67.5 years of age reported reduced carotid intima-media thickness, smaller plaque and improved lipids at 10,800 FU per day — including a 15.8% increase in HDL cholesterol [3]. At 3,600 FU per day, the same study found nothing.

That is a genuine dose-response signal, and it deserves two caveats stated plainly. The study was retrospective and uncontrolled — no placebo group — and several authors were affiliated with the manufacturer of the nattokinase preparation used. A corrigendum was issued in December 2022 correcting baseline data. It is the largest human dataset available, and it is also the weakest study design among the trials cited here.

The practical reading: 2,000 FU is the dose with randomised evidence behind it, and 10,800 FU is the dose with the strongest observational signal for arterial outcomes. Anyone considering the higher end should be doing so with a physician, not on the basis of a blog. Our article on nattokinase side effects sets out what changes as the dose rises.

5. The Three-Year Trial That Found Nothing

The longest randomised trial of nattokinase is the one most dosage guides leave out. Researchers randomised 265 individuals of median age 65.3, none with clinical cardiovascular disease, to 2,000 FU daily or matching placebo, with carotid ultrasound every 6 months. After a median of three years, they found no significant difference in carotid intima-media thickness, arterial stiffness, blood pressure or any laboratory determination [2].

This does not mean the dose is inert. It means baseline determines what is available to change. The 2008 trial recruited people with systolic pressure of 130–159 mmHg and found an effect; the three-year trial recruited healthy, low-risk adults and found none. You cannot lower a number that is already normal.

So the honest answer to "how much per day" includes a prior question: what are you starting from? For someone with pressure in the prehypertensive range, 2,000 FU has randomised support. For a healthy 45-year-old with normal readings, three years of the same dose produced nothing measurable.

6. When to Take Your Daily Dose

Nattokinase is a protein, and stomach acid degrades proteins. The standard protocol across the research is a single daily dose taken on an empty stomach — the 2016 North American trial instructed participants to take one capsule daily in the morning [6], and recorded 96.4% average compliance.

Splitting the dose has no evidence behind it. Every trial cited here used once-daily administration, and single-dose pharmacokinetic work in 11 volunteers found peak serum concentrations at 13.3 ± 2.5 hours after dosing [9] — a long enough tail that twice-daily dosing offers no obvious advantage at the standard amount.

Delivery format matters as much as timing. A capsule that dissolves in the stomach exposes the enzyme to acid before it reaches the small intestine, which is the argument for delayed-release capsules over standard ones. If you have been taking your dose with meals and seen nothing at week 8, correcting the timing is a reasonable step before changing the amount.

7. Upper Limits, and Who Should Take None

There is no established upper limit for nattokinase, which is a reason for caution rather than confidence. The 10,800 FU daily dose was described as well tolerated over 12 months in the 1,062-participant study, but that trial had no control group and relied on participant-reported adverse events [3].

The documented harms cluster around combination with other antithrombotics. A published case report describes acute cerebellar haemorrhage in a patient already taking aspirin for secondary stroke prevention, after nattokinase 400 mg daily for 7 consecutive days [8], with multiple cerebral microbleeds on MRI. Memorial Sloan Kettering also records valve thrombosis in a patient who self-substituted nattokinase for warfarin [10].

The correct dose for several groups is zero. Standard guidance is to avoid nattokinase in ischaemic stroke, peptic ulcer and coagulation disorders, and before and after surgery [9], with use in pregnancy and lactation not supported by safety data. Anyone on warfarin, apixaban, rivaroxaban, aspirin or clopidogrel should not begin without physician oversight — our guide to nattokinase as a natural blood thinner covers those interactions in detail.

8. BioAbsorb Nattokinase Enzyme: 2,000 FU, Verified Per Batch

Because fibrinolytic units measure activity rather than weight, a label can state 2,000 FU while the enzyme inside has degraded — and nothing you feel will tell you the difference. Verification is the only assurance available.

BioAbsorb Nattokinase Enzyme delivers 100 mg providing 2,000 FU per capsule, taken as one capsule daily on an empty stomach — the same amount and schedule used in the 2008 blood pressure trial and the three-year prevention study. Every batch is third-party tested to confirm at least 2,000 FU of activity, alongside screening for heavy metals, gluten and microbial contaminants.

Three formulation choices are relevant to dosing specifically. The capsule uses DRcaps delayed-release technology, protecting the enzyme from stomach acid without the phthalates and plasticizers found in conventionally enteric-coated capsules. The formula is free of vitamin K2 — which matters because K2 promotes clotting and complicates matters for anyone on warfarin or already supplementing it, and because the North American trial that recorded diastolic reductions used K2-removed nattokinase. And it is non-GMO, 100% vegetarian and free of gluten, nuts, eggs, dairy, fish and shellfish, manufactured in a Canadian GMP-certified facility.

Pricing runs $28.18 for 60 capsules or $49.87 for 180 — a six-month supply at one capsule daily, working out to roughly $0.28 per day.

Frequently Asked Questions

Is 2,000 FU of nattokinase enough?

For blood pressure support in people with elevated readings, yes — that is the dose with randomised evidence behind it, producing a 5.55 mmHg systolic reduction over 8 weeks. For arterial plaque or lipid endpoints, the evidence suggests it is not enough; those outcomes only moved at 10,800 FU daily in the available data.

Can I take 4,000 FU per day?

That dose has been used in published research. An open-label trial gave 45 adults two 2,000 FU capsules daily for two months and recorded reductions in fibrinogen, Factor VII and Factor VIII without notable adverse events. Discuss it with a physician first, particularly if you take any antiplatelet or anticoagulant medication.

Should I take nattokinase in the morning or at night?

The trials that reported timing used a single morning dose on an empty stomach, and compliance in that protocol averaged 96.4%. There is no head-to-head evidence favouring evening dosing, so consistency matters more than the specific hour.

How much natto would I have to eat instead?

A standard serving of natto supplies roughly 1,400 to 2,000 FU, so one serving approximates a single capsule — but it also delivers substantial vitamin K2, which is a problem for anyone on warfarin. Our article on dietary sources of nattokinase compares the two routes in full.

How long before I should expect anything at this dose?

Eight weeks is the evidence-based window, since both randomised blood pressure trials ran to that point and the 2008 study saw changes at 8 weeks but not at 4. Biochemical effects from a single dose appear within 2 to 8 hours, but they are not something you can perceive.

Is a higher dose safer if I stop my prescription blood thinner?

No — substituting nattokinase for prescribed anticoagulation is dangerous at any dose. Memorial Sloan Kettering documents mechanical valve thrombosis requiring repeat surgery in a patient who made that substitution. Never stop a prescribed medication without your physician's direction.

Conclusion

Take 2,000 FU once daily on an empty stomach if you want the dose with randomised evidence behind it, understand that arterial endpoints only responded at 10,800 FU per day in observational data, and involve a physician before going higher or if you take any antithrombotic medication. If you want a capsule whose activity is verified rather than assumed, BioAbsorb Nattokinase Enzyme is third-party tested for 2,000 FU per capsule.

Research References

1. Effects of nattokinase on blood pressure: a randomized, controlled trial. Hypertension Research, Vol. 31, Issue 8 (2008). Randomised, double-blind, placebo-controlled trial in 86 adults aged 20–80 with untreated systolic pressure of 130–159 mmHg; among 73 completers, 2,000 FU daily for 8 weeks produced net reductions of 5.55 mmHg systolic and 2.84 mmHg diastolic versus control.
2. Nattokinase atherothrombotic prevention study: a randomized controlled trial. Clinical Hemorheology and Microcirculation, Vol. 78, Issue 4 (2021), pp. 339–353. 265 individuals of median age 65.3 without clinical cardiovascular disease received 2,000 FU or placebo; after a median of three years there was no significant difference in carotid intima-media thickness, arterial stiffness, blood pressure or any laboratory determination.
3. Effective management of atherosclerosis progress and hyperlipidemia with nattokinase: a clinical study with 1,062 participants. Frontiers in Cardiovascular Medicine, Vol. 9 (2022). Retrospective, non-randomised study without placebo control; participants averaging 67.5 years showed reduced carotid plaque, intima-media thickness and lipids plus a 15.8% HDL increase after 12 months at 10,800 FU per day, while 3,600 FU per day was ineffective. Several authors were affiliated with the manufacturer of the preparation tested, and a corrigendum was issued in December 2022.
4. A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles. Scientific Reports, Vol. 5 (2015). Double-blind placebo-controlled crossover study in 12 healthy young males; a single 2,000 FU dose altered D-dimer, Factor VIII activity and clotting time across blood draws at 2, 4, 6 and 8 hours, with all changes remaining within normal reference range.
5. Nattokinase decreases plasma levels of fibrinogen, factor VII, and factor VIII in human subjects. Nutrition Research, Vol. 29, Issue 3 (2009), pp. 190–196. Open-label, self-controlled trial in 45 adults across healthy, cardiovascular-risk and dialysis groups taking two 2,000 FU capsules daily for two months; fibrinogen fell 7–10%, Factor VII 7–14% and Factor VIII 17–19%, with no notable adverse events.
6. Consumption of nattokinase is associated with reduced blood pressure and von Willebrand factor: results from a randomized, double-blind, placebo-controlled, multicenter North American clinical trial. Integrated Blood Pressure Control, Vol. 9 (2016), pp. 95–104. Used K2-removed nattokinase encapsulated at 100 mg standardised to at least 2,000 FU per daily dose, taken as one capsule each morning for 8 weeks, with average compliance of 96.4%. The study was sponsored by the distributor of the product tested.
7. Nattokinase supplementation and cardiovascular risk factors: a systematic review and meta-analysis of randomized controlled trials. Reviews in Cardiovascular Medicine, Vol. 24, Issue 8 (2023). Pooled randomised controlled trials and found a mean diastolic blood pressure reduction of 2.32 mmHg versus placebo, with no notable adverse events attributed to nattokinase intake across the included studies.
8. Cerebellar hemorrhage provoked by combined use of nattokinase and aspirin in a patient with cerebral microbleeds. Internal Medicine, Vol. 47, Issue 5 (2008), pp. 467–469. Case report of acute cerebellar haemorrhage in a patient taking aspirin for secondary stroke prevention, after 7 consecutive days of nattokinase 400 mg daily, with multiple cerebral microbleeds demonstrated on MRI. Causality cannot be established from a single case.
9. Nattokinase. Drugs.com professional monograph (2026). Records 100 mg daily (equivalent to 2,000 FU) for 8 weeks as the dose used in fibrinolytic and blood pressure studies, peak serum concentration at 13.3 ± 2.5 hours in 11 volunteers, and advises avoidance in ischaemic stroke, peptic ulcer, coagulation disorders, around surgery, and in pregnancy and lactation.
10. Nattokinase. Memorial Sloan Kettering Cancer Center, Integrative Medicine herb monograph. Records increased intracerebral haemorrhage risk when combined with aspirin, and a case of mechanical valve thrombosis requiring repeat valve replacement after a patient self-substituted nattokinase for warfarin.

About the Author

David Kimbell is a health writer, digital entrepreneur and former aerospace engineer, based in Ottawa, Canada. He loves translating complex science into clear, actionable guidance for consumers seeking evidence-based solutions.

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Important Disclaimers

Medical Disclaimer: This article provides educational information only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement, especially if you have existing health conditions, take medications, or are pregnant or nursing.

FDA/Health Canada Statement: These statements have not been evaluated by the Food and Drug Administration or Health Canada. This product is not intended to diagnose, treat, cure, or prevent any disease.