What 10,800 FU Means: Nattokinase Activity, Not mg
Updated: 5 days ago
Nattokinase dosage is measured in FU — fibrinolytic units — not milligrams, and that single fact explains most of the confusion on supplement shelves. Two bottles can list the same "100 mg" and deliver very different enzyme activity. So a label reading nattokinase 10,800 FU is telling you how much fibrin-degrading activity one serving carries, not how much powder it weighs. The research on nattokinase has used anywhere from 2,000 FU to 10,800 FU per day, and the results differ by dose and by how the studies were designed. This guide explains what FU measures, what each major study actually used, what the label numbers mean, and who should talk to a clinician before taking any nattokinase product.
What "FU" actually measures (and why milligrams tell you almost nothing)
Nattokinase is an enzyme — specifically a serine protease of 275 amino acids, weighing about 27.7 kilodaltons, first isolated from natto, the traditional Japanese food of soybeans fermented with Bacillus subtilis (natto strain). The researcher Hiroyuki Sumi identified its fibrin-degrading activity in 1980 while working at Chicago University Medical School (Weng et al., 2017).
Because it is an enzyme, what matters is not how much of it you swallow by weight but how much work it can do. Enzyme preparations vary in purity and potency, so the industry standardized on an activity unit. The Japan NattoKinase Association (JNKA) puts it plainly: FU is "the unit that indicates the activity of nattokinase," measured by how much fibrin — the protein mesh at the center of clotting — the enzyme breaks down in a standardized laboratory assay (JNKA FAQ).
The practical consequence: a milligram figure on a nattokinase label is a weight of powder, not a measure of activity. If a product does not state FU, you cannot compare it to anything in the research. If it states FU per capsule but a serving is two capsules, the number you care about is FU per serving. (Our own Great Billiom Nattokinase 10,800 FU label, for instance, prints the per-serving figure directly under the product name so there is no arithmetic to do.) Every enzyme supplement has an equivalent activity unit, incidentally — DAO enzyme is standardized in HDU, and the same read-the-units logic applies; see our guide to how DAO enzyme works and how to read its dosage.)
Where the 2,000 FU number comes from
Almost every nattokinase conversation starts at 2,000 FU per day, and it helps to know why. The JNKA recommends 2,000 FU as a daily intake, and it anchors that figure in the food itself: a 50-gram pack of natto contains, on average, about 1,500 FU of nattokinase activity, so "about 1 to 2 packs of natto" a day gets you there (JNKA FAQ). If you are weighing the food against the capsule, our natto vs nattokinase comparison covers what else the fermented beans deliver — including their vitamin K2.
That number then flowed into the early clinical trials. The 2008 randomized, double-blind, placebo-controlled trial by Kim and colleagues used a single 2,000 FU capsule daily for eight weeks in 86 adults (73 completed) aged 20 to 80 who were not on blood-pressure medication and had systolic readings between 130 and 159 mmHg. Compared with placebo, systolic pressure was 5.55 mmHg lower (95% CI −10.5 to −0.57), diastolic was 2.84 mmHg lower (a difference the authors reported as not statistically significant), and plasma renin activity fell (Kim et al., 2008, *Hypertension Research*).
So 2,000 FU is a food-equivalent dose with one positive eight-week trial behind it. It is not the only dose the research has tested — and the larger and longer studies complicate the picture.
What the research actually used, study by study
Four pieces of evidence matter most when you are deciding what dose to look for. They span 8 weeks to 3 years and 2,000 FU to 10,800 FU, and they do not all point the same way. Reading them side by side is the honest way to understand nattokinase dosage.
Study | Design | Participants | Daily dose | Duration | What it measured | What it found |
Randomized, double-blind, placebo-controlled | 86 adults, SBP 130–159 mmHg, no BP medication | 2,000 FU | 8 weeks | Blood pressure, renin | SBP −5.55 mmHg vs placebo | |
Randomized, double-blind, placebo-controlled | 265 healthy adults at low cardiovascular risk | 2,000 FU | Median 3 years | Carotid intima-media thickness, arterial stiffness | No difference from placebo | |
Systematic review and meta-analysis of 6 RCTs | 546 pooled | 1,200–8,000 FU | 8 weeks to 3 years | Blood pressure, lipids, glucose | SBP −3.45 mmHg, DBP −2.32 mmHg; no lipid-lowering at low doses | |
Retrospective observational (not randomized); 5 of 10 authors employed by a nattokinase manufacturer | 1,062 adults, mean age 67.5 | 10,800 FU (n=1,001) vs 3,600 FU (n=61) | 12 months | Lipids, carotid ultrasound | Lipid and carotid measures changed favorably in the 10,800 FU group |
Three things stand out from that table.
First, the two most rigorously designed trials both used 2,000 FU. Kim found a modest blood-pressure difference over eight weeks. Hodis — the longest and most rigorous nattokinase trial to date — followed 265 healthy, low-risk adults for a median of three years and concluded that "nattokinase supplementation has a null effect on subclinical atherosclerosis progression in healthy individuals at low risk for CVD" (Hodis et al., 2021). At 2,000 FU, in healthy people, artery structure did not change.
Second, when the 2023 meta-analysis pooled six randomized trials (doses from 1,200 to 8,000 FU), the blood-pressure effect held up — systolic 3.45 mmHg lower, diastolic 2.32 mmHg lower than placebo — but lipids did not move at low doses. The authors wrote that "relatively low-dose supplementation of nattokinase may have no significant lipid-lowering effect" and that the question of dose-dependency "requires further investigation" (Li et al., 2023). No adverse events were reported across the included trials.
Third, the largest dataset by far — 1,062 participants over 12 months — used 10,800 FU per day, and it reported changes across total cholesterol (−15.9%), triglycerides (−15.7%), LDL-C (−18.1%) and HDL-C (+15.8%) in that group, along with changes in carotid ultrasound measures, with "no noticeable adverse effects" recorded (Chen et al., 2022). But this study carries two caveats you should weigh. The first, its own authors state directly: "it represents a retrospective study and not a randomized control trial." There was no placebo group, no follow-up after the 12 months, and lifestyle data were self-reported. The second is in the conflict-of-interest statement: five of the ten authors were employed by Sungen Bioscience Co. Ltd., a nattokinase manufacturer. Neither caveat makes the data worthless — it is still the biggest and longest nattokinase dataset at the highest dose — but observational, industry-affiliated research can show an association; it cannot prove the dose caused the change.
The dose question nobody on the label answers
Put those findings together and a pattern emerges that most supplement marketing skips over. At 2,000 FU, the randomized evidence supports a modest blood-pressure effect and nothing more. The only data suggesting broader effects come from a much higher dose, 10,800 FU, in an industry-affiliated study design that cannot establish cause. The meta-analysis authors' own conclusion — that low doses may not be enough for lipid outcomes and dose-dependency needs proper testing — is the most accurate one-sentence summary of where nattokinase research stands.
For a shopper, that translates into two honest statements. If you want the dose with the strongest trial evidence for blood pressure, that is 2,000 FU. If you want the dose used in the largest and longest study, that is 10,800 FU — with the caveat that a randomized trial at that dose has not yet been published. Neither is "wrong." What is wrong is a label that lists milligrams only, or lists FU per capsule in large type and the two-capsule serving in fine print, so you cannot tell which of these doses you are actually getting.
How to read a nattokinase label in 60 seconds
Once you know FU is the currency, reading a label is a matter of checking six things in order.
FU per serving, not per capsule. Find the Supplement Facts serving size first. A product stating "5,400 FU" per capsule with a two-capsule serving delivers 10,800 FU; one stating "2,000 FU" with a one-capsule serving delivers 2,000 FU. Do the multiplication before you compare prices.
A stated FU at all. If the label gives only milligrams of "nattokinase powder," there is no way to relate it to any study in the table above.
Capsule type. Nattokinase is a protein, and the JNKA notes that capsule forms withstand stomach acid better than whole natto does; the enzyme is absorbed lower in the digestive tract (JNKA FAQ; Weng et al., 2017). Delayed-release or enteric-coated capsules are designed to open further along, which is why several manufacturers now use them. Consider it a fact worth checking, not a unique selling point.
Vitamin K2 — present or removed? Natto is naturally rich in vitamin K2, and some extracts keep it while others strip it out. This matters enormously if you take warfarin (see the safety section below), so the label should be explicit either way.
Soy disclosure. Nattokinase is made from fermented soybeans. A product cannot be soy-free; a label that claims otherwise is a red flag.
Third-party testing. Enzyme activity degrades with heat and moisture — the JNKA notes activity "drops sharply" above 50 °C in humid conditions — so a stated FU is only meaningful if someone has verified it in the finished product.
Timing: what the tradition and the label say
The JNKA's guidance is that nattokinase is "most effective to take between after dinner and before sleep," reasoning that the body's fluid balance and circulation change overnight (JNKA FAQ). Most manufacturers pair that with an empty-stomach instruction — typically one hour before or two hours after a meal — because the enzyme is a protein and the goal is to reduce its exposure to a full, acidic stomach. Neither timing rule has been tested head-to-head in a published trial, so follow the specific product's directions rather than improvising.
Who should not take nattokinase without talking to a clinician
This is the section that matters more than any dose number. Nattokinase acts on fibrin, and Memorial Sloan Kettering Cancer Center's About Herbs database is specific about the consequences: nattokinase "may increase the risk of bleeding" when combined with anticoagulants, may increase the effects of daily aspirin, and — because natto-derived products often contain vitamin K — "can reduce the effects of warfarin." MSKCC also notes a theoretical concern about an existing clot dislodging, and cites case reports of serious bleeding in people taking over-the-counter nattokinase. Its guidance is that people with coagulation disorders or on anticoagulant medication should avoid it entirely (MSKCC, About Herbs: Nattokinase).
Add to that list anyone scheduled for surgery (most manufacturers advise stopping two weeks before), anyone who is pregnant or nursing, and children. If you are on any medication that affects clotting — warfarin, aspirin, clopidogrel, apixaban, rivaroxaban, or similar — do not start nattokinase without your prescriber's explicit agreement, regardless of what dose the bottle says.
Where Great Billiom Nattokinase 10,800 FU fits
We built our formula around the label-reading checklist above, so it is worth showing exactly how it reads.
Each two-capsule serving of Great Billiom Nattokinase 10,800 FU delivers 10,800 FU of nattokinase — the same daily amount used in the Chen 2022 study's larger group, with all the caveats above — plus 180 mcg of vitamin K2 as MK-7 and 240,000 SPU of serrapeptase. The capsules are delayed-release vegetarian HPMC (no gelatin), 90 to a bottle for 45 servings. The label states the FU per serving, the K2 content, and the soy origin in plain type, and every batch is third-party tested in a GMP-certified US facility. It is $19.99 per bottle, or $17.99 with Subscribe & Save.
In structure/function terms, the formula is designed to support healthy blood flow and circulation, healthy fibrin metabolism, and cardiovascular wellness as part of an active lifestyle for adults 40 and over, with K2 MK-7 supporting calcium delivery to bones and teeth.* It contains soy, is vegetarian rather than vegan, and is not for anyone on anticoagulant or antiplatelet medication without a clinician's sign-off. The suggested use is two capsules daily on an empty stomach, at least one hour before or two hours after a meal.
Key takeaways
Nattokinase is dosed in FU (fibrinolytic units), a measure of enzyme activity. Milligrams alone tell you nothing about potency.
2,000 FU/day is the JNKA's recommended intake (roughly 1–2 packs of natto) and the dose in the most rigorously designed trials, which found a modest blood-pressure effect and no change in artery structure over three years in healthy adults.
10,800 FU/day is the dose used in the largest and longest study (1,062 people, 12 months) — a retrospective study, not a randomized trial.
Read FU per serving, check capsule type, K2 content, soy disclosure and third-party testing.
Anyone on anticoagulants, antiplatelets or warfarin, or facing surgery, should not take nattokinase without medical advice.
If you have read this far, you already know more about nattokinase dosage than most labels assume. When you are ready to compare, the Great Billiom Nattokinase 10,800 FU page lists every figure discussed here — FU per serving, K2 MK-7, serrapeptase, capsule type and third-party testing — in one place, and ships within the USA.
Frequently asked questions
What does FU stand for in nattokinase?
FU stands for fibrinolytic units. It is a standardized laboratory measure of how much fibrin-degrading activity a nattokinase preparation has, defined by the Japan NattoKinase Association. Because nattokinase is an enzyme, FU — not milligrams — is the number that lets you compare one product with another or with a published study.
How much nattokinase per day did the research use?
Published human studies have used 1,200 to 10,800 FU per day. The randomized trials by Kim (2008) and Hodis (2021) used 2,000 FU. The 2023 meta-analysis pooled trials from 1,200 to 8,000 FU. The Chen (2022) retrospective study of 1,062 people used 10,800 FU in its main group and 3,600 FU in a smaller comparison group.
Is 2,000 FU of nattokinase enough?
It depends what you are looking at. In randomized trials, 2,000 FU was associated with a modest blood-pressure difference versus placebo over eight weeks, but a three-year trial in healthy low-risk adults found no effect on artery measures. The 2023 meta-analysis concluded low doses may have no lipid-lowering effect and that dose-dependency needs further study.
When should I take nattokinase?
The Japan NattoKinase Association suggests taking it between after dinner and before sleep. Most product labels also advise an empty stomach — one hour before or two hours after eating — to limit the enzyme's exposure to a full stomach. No published trial has compared timings directly, so follow your product's directions.
Can I take nattokinase with blood thinners?
Not without your prescriber's agreement. Memorial Sloan Kettering notes that nattokinase may increase bleeding risk with anticoagulants and aspirin, and that vitamin K in natto-derived products can reduce warfarin's effect. People with coagulation disorders or on anticoagulant medication are advised to avoid it.
Megan Elliott, Content Editor at Great Billiom. Every claim in this article is sourced from the primary research linked above. Read our editorial standards → thegreatbilliom.com/editorial-standards
Sources
Japan NattoKinase Association. Frequently Asked Questions. https://j-nattokinase.org/en/faq/
Weng Y, Yao J, Sparks S, Wang KY. Nattokinase: An Oral Antithrombotic Agent for the Prevention of Cardiovascular Disease. Int J Mol Sci. 2017;18(3):523. https://www.mdpi.com/1422-0067/18/3/523
Kim JY, et al. Effects of nattokinase on blood pressure: a randomized, controlled trial. Hypertens Res. 2008;31(8):1583–1588. https://www.nature.com/articles/hr2008203
Hodis HN, et al. Nattokinase atherothrombotic prevention study: A randomized controlled trial. Clin Hemorheol Microcirc. 2021. https://journals.sagepub.com/doi/abs/10.3233/CH-211147
Li X, et al. Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Rev Cardiovasc Med. 2023;24(8):234. https://www.imrpress.com/journal/RCM/24/8/10.31083/j.rcm2408234
Chen H, et al. Effective management of atherosclerosis progress and hyperlipidemia with nattokinase: A clinical study with 1,062 participants. Front Cardiovasc Med. 2022;9:964977. https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2022.964977/full
Memorial Sloan Kettering Cancer Center. About Herbs: Nattokinase. https://www.mskcc.org/cancer-care/integrative-medicine/herbs/nattokinase
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary. This article is for educational purposes and is not medical advice; consult a qualified healthcare professional before starting any supplement, especially if you take medication or have a medical condition.
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