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Nattokinase
Nattokinase has a small, real signal for blood pressure in mild hypertensives and clear biomarker effects on fibrinolysis, but the human evidence stops well short of what supplement marketing claims.
- Evidence
- Weak Evidence
- Category
- Heart & Cardiovascular
- Best form
- NSK-SD (Japan Bio Science Lab patented extract, vitamin K2 removed, 2,000 FU per 100mg) - the only form with clinical trial data
- Effective dose
- 100-200mg daily (2,000-4,000 FU) of a standardized extract, ideally NSK-SD
- Lab tested
- 2 of 10 products
- Category
- Heart & Cardiovascular
- Best form
- NSK-SD (Japan Bio Science Lab patented extract, vitamin K2 removed, 2,000 FU per 100mg) - the only form with clinical trial data
- Effective dose
- 100-200mg daily (2,000-4,000 FU) of a standardized extract, ideally NSK-SD
- Lab tested
- 2 of 10 products
Key takeaways
- →Real but small BP effect (around 3-5 mmHg) in mild hypertensives at 100mg / 2,000 FU/day; no proven stroke or heart attack prevention.
- →Use NSK-SD specifically and look for FU activity on the label. Generic mg-only nattokinase is not the studied product.
- →Spike protein and long COVID claims have no human evidence. The cited 2022 study was a Petri dish, not a trial.
- →Do not combine with warfarin, DOACs, aspirin, or other anticoagulants. Bleeding case reports exist.
What Is Nattokinase?
Nattokinase has a small, real signal for blood pressure in mild hypertensives and clear biomarker effects on fibrinolysis, but the human evidence stops well short of what supplement marketing claims. Two 8-week RCTs (Kim 2008 in Korea, Jensen 2016 in North America) found roughly 3-5 mmHg reductions in systolic and diastolic BP at 100mg/day (2,000 FU). A 2023 meta-analysis of 6 RCTs (n=546) confirmed the BP signal but found lipid effects were inconsistent and dose-dependent. There are zero RCTs showing nattokinase prevents stroke, heart attack, or death. The dosing reality matters more than mg: clinical trials use NSK-SD specifically, and the standardization unit is FU (fibrinolytic units), not milligrams. A 100mg capsule of generic nattokinase with no FU disclosure is not the same product that was studied.
The fibrinolysis story is interesting but limited. Hsia 2009 found 7-19% reductions in fibrinogen, factor VII, and factor VIII after 2 months in 45 subjects across healthy, cardiovascular-risk, and dialysis groups. These are real biomarker shifts. They are not equivalent to clinical anticoagulation, and no head-to-head trial has compared nattokinase to aspirin, warfarin, or any DOAC. The often-cited LONFLIT-FLITE trial for DVT prevention on long flights (Cesarone 2003) used a combination product with Pycnogenol, so nattokinase's individual contribution to that result cannot be isolated.
The post-2020 marketing of nattokinase for "spike protein clearance" or "long COVID" deserves a flat answer: there is no clinical evidence supporting these uses. The Tanikawa 2022 in vitro study showed that nattokinase can degrade spike protein in cell culture at concentrations that have nothing to do with what circulates in human blood after oral dosing. It was a Petri-dish finding, not a treatment study. No human trial has tested nattokinase for COVID, post-COVID symptoms, or vaccine-related concerns. Anyone selling it for those reasons is ahead of the data.
Safety in healthy adults appears acceptable at 100-200mg/day, but the combination with anticoagulants is the real concern. Case reports of bleeding events exist when nattokinase is taken alongside warfarin, aspirin, or DOACs. Anyone on blood thinners, with a bleeding disorder, recently post-surgery, or pregnant should not take nattokinase without physician oversight.
Does It Work? The Evidence
How A-F grades workBlood pressure reduction in mild hypertensives
Kim 2008 RCT (n=86, 8 weeks, 2,000 FU/day): SBP -5.55 mmHg, DBP -2.84 mmHg vs placebo; Jensen 2016 RCT (n=79, 8 weeks, 100mg/day): DBP 87->84 mmHg, P<0.05; Li 2023 meta-analysis of 6 RCTs (n=546) confirmed significant BP reduction
Fibrinolytic and coagulation biomarker effects
Hsia 2009 trial (n=45 across 3 groups, 2 months): fibrinogen -7-10%, factor VII -7-14%, factor VIII -17-19%; biomarker shifts only, not hard clinical endpoints
Lipid panel improvement (cholesterol, triglycerides)
Li 2023 meta-analysis: low-dose trials showed unfavorable lipid changes; high-dose subgroups showed elevated total cholesterol with no HDL/LDL change; Chen 2022 (n=1,062, 10,800 FU/day) reported lipid improvement but at 5x the typical clinical dose
DVT prevention during long-haul flights or surgery
Cesarone 2003 LONFLIT-FLITE RCT (n=204): combination Flite Tabs (nattokinase + Pycnogenol) reduced DVT incidence, but the combo design means nattokinase's individual contribution is undefined; no standalone nattokinase DVT trial exists
Spike protein clearance or long COVID treatment
Tanikawa 2022 was an in vitro cell-culture study using HEK293 cells, not a human trial; zero clinical trials in COVID, post-COVID, or vaccine-related contexts; the in vitro concentrations bear no relationship to plasma levels after oral dosing
| Grade | Claimed Benefit | Key Studies | Our Verdict |
|---|---|---|---|
| B | Blood pressure reduction in mild hypertensives | Kim 2008 RCT (n=86, 8 weeks, 2,000 FU/day): SBP -5.55 mmHg, DBP -2.84 mmHg vs placebo; Jensen 2016 RCT (n=79, 8 weeks, 100mg/day): DBP 87->84 mmHg, P<0.05; Li 2023 meta-analysis of 6 RCTs (n=546) confirmed significant BP reduction | Early Signal |
| B | Fibrinolytic and coagulation biomarker effects | Hsia 2009 trial (n=45 across 3 groups, 2 months): fibrinogen -7-10%, factor VII -7-14%, factor VIII -17-19%; biomarker shifts only, not hard clinical endpoints | Early Signal |
| C | Lipid panel improvement (cholesterol, triglycerides) | Li 2023 meta-analysis: low-dose trials showed unfavorable lipid changes; high-dose subgroups showed elevated total cholesterol with no HDL/LDL change; Chen 2022 (n=1,062, 10,800 FU/day) reported lipid improvement but at 5x the typical clinical dose | Conflicted |
| C | DVT prevention during long-haul flights or surgery | Cesarone 2003 LONFLIT-FLITE RCT (n=204): combination Flite Tabs (nattokinase + Pycnogenol) reduced DVT incidence, but the combo design means nattokinase's individual contribution is undefined; no standalone nattokinase DVT trial exists | Not There Yet |
| F | Spike protein clearance or long COVID treatment | Tanikawa 2022 was an in vitro cell-culture study using HEK293 cells, not a human trial; zero clinical trials in COVID, post-COVID, or vaccine-related contexts; the in vitro concentrations bear no relationship to plasma levels after oral dosing | Ineffective |
How to Choose: Forms, Doses & What Matters
Clinical dose: 100-200mg daily (2,000-4,000 FU) of a standardized extract, ideally NSK-SD
Best forms: NSK-SD (Japan Bio Science Lab patented extract, vitamin K2 removed, 2,000 FU per 100mg) - the only form with clinical trial data, Standardized capsules disclosing FU activity per dose; mg alone tells you nothing
100mg (2,000 FU) once or twice daily, taken on an empty stomach for best absorption. Some people prefer evening dosing because the fibrinolytic activity is theoretically aligned with overnight clot risk, but no trial has confirmed timing matters. Effects on BP and biomarkers typically appear over 4-8 weeks of consistent use. If you choose a product without disclosed FU activity, you are taking an unstandardized supplement and dosing comparisons to clinical trials do not apply. Discontinue at least 2 weeks before any planned surgery or dental procedure.
Who Should Take Nattokinase?
Adults with mild hypertension or pre-hypertension looking for a small adjunct to lifestyle changes. People with a family history of clotting risk who want fibrinolytic support and are not on anticoagulants. Those interested in the cardiovascular-marker effects (fibrinogen, factor VII/VIII) for general wellness. Most healthy adults will see modest or no perceptible benefit from nattokinase alone.
Who Should Avoid It?
Not for everyone
Side Effects & Safety
Product Scores
10 products scored on dosing accuracy, third-party testing, cost per effective dose, and label transparency.
The Scorecard: 10 Products Compared
Nattokinase 2,000 FU
Doctor's Best$23.99 ÷ 89 days at 100mg/day (1 serving × 100mg)
Doctor's Best is one of the more transparent NSK-SD products on the market at a reasonable price
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
NSK-SD Nattokinase 100mg
Source Naturals
$19.95 ÷ 60 days at 100mg/day (1 serving × 100mg)
Source Naturals was one of the earliest US brands to license NSK-SD and remains a benchmark for label transparency
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
Nattokinase 100mg (2,000 FU)
NOW Foods$12.99 ÷ 62 days at 100mg/day (1 serving × 100mg)
NOW Foods runs one of the most respected in-house testing programs in the supplement industry
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
NSK-SD Nattokinase 100mg
Pure Encapsulations$32.80 ÷ 60 days at 100mg/day (1 serving × 100mg)
Pure Encapsulations is the practitioner-channel pick for patients with multiple sensitivities
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
Nattokinase 2,000 FU (100mg)
Healthy Origins
$28.99 ÷ 181 days at 100mg/day (1 serving × 100mg)
Healthy Origins is the bulk-buy value play if you want a sustained supply at the clinical dose
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
NattoMax 2,000 FU 100mg
Jarrow Formulas$11.95 ÷ 30 days at 100mg/day (1 serving × 100mg)
Jarrow's vitamin K-removed formulation is the safer pick if your physician is monitoring INR
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
NattoZyme 100mg (NSK-SD)
Allergy Research Group
$30.00 ÷ 60 days at 100mg/day (1 serving × 100mg)
Allergy Research Group's testing protocols are stricter than most, useful for sensitive patients
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
Natto-K (Nattokinase)
Life Extension$36.00 ÷ 90 days at 100mg/day (1 serving × 100mg)
Life Extension publishes detailed product test summaries on their site for those who want to verify
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
NSK-SD Nattokinase 100mg
Himalaya
$24.99 ÷ 60 days at 100mg/day (1 serving × 100mg)
Himalaya brings botanical-manufacturing experience to the NSK-SD category at a mid-tier price point
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
Nattokinase 1,250 FU (100mg, Enteric Coated)
Solaray
$14.99 ÷ 30 days at 100mg/day (1 serving × 100mg)
Underdosed for the clinical benchmark, but the enteric coating is a legitimate quality feature most competitors skip
Prices checked 2026-04-26. Cost shown is per clinically effective daily dose, not per pill.
Full Comparison
| Category | Nattokinase 2,000 FU Doctor's Best | NSK-SD Nattokinase 100mg Source Naturals | Nattokinase 100mg (2,000 FU) NOW Foods | NSK-SD Nattokinase 100mg Pure Encapsulations | Nattokinase 2,000 FU (100mg) Healthy Origins | NattoMax 2,000 FU 100mg Jarrow Formulas | NattoZyme 100mg (NSK-SD) Allergy Research Group | Natto-K (Nattokinase) Life Extension | NSK-SD Nattokinase 100mg Himalaya | Nattokinase 1,250 FU (100mg, Enteric Coated) Solaray |
|---|---|---|---|---|---|---|---|---|---|---|
| Brand Score | 88/100Winner | 87/100 | 86/100 | 85/100 | 84/100 | 84/100 | 84/100 | 83/100 | 82/100 | 70/100 |
| Dosing & Form | 25/25Winner | 25/25 | 25/25 | 25/25 | 25/25 | 25/25 | 25/25 | 22/25 | 25/25 | 13/25 |
| Purity | 19/25 | 19/25 | 19/25 | 22/25Winner | 17/25 | 17/25 | 19/25 | 19/25 | 17/25 | 17/25 |
| Value | 22/25 | 20/25 | 23/25Winner | 15/25 | 23/25 | 19/25 | 17/25 | 19/25 | 19/25 | 18/25 |
| Transparency | 22/25 | 23/25Winner | 19/25 | 23/25 | 19/25 | 23/25 | 23/25 | 23/25 | 21/25 | 22/25 |
| Cost/Day | $0.27 | $0.33 | $0.21 | $0.55 | $0.16Winner | $0.40 | $0.50 | $0.40 | $0.42 | $0.50 |
| Dose/Serving | 100mg | 100mg | 100mg | 100mg | 100mg | 100mg | 100mg | 100mg | 100mg | 100mg |
| Form | NSK-SD Nattokinase capsule (2,000 FU) | NSK-SD Nattokinase vegan capsule (2,000 FU) | Nattokinase capsule (2,000 FU, from non-GMO soy) | NSK-SD Nattokinase hypoallergenic capsule (2,000 FU) | Nattokinase vegetarian capsule (2,000 FU, non-GMO soy) | Highly purified nattokinase capsule (2,000 FU, vitamin K removed) | NSK-SD Nattokinase softgel (2,000 FU, non-GMO soy) | NSK-SD Nattokinase vegetarian capsule (2,000 FU) | NSK-SD Nattokinase vegan capsule (2,000 FU) | Nattokinase enteric-coated capsule (1,250 FU) |
| Third-Party Tested | No | No | No | ✓ Yes | No | No | No | ✓ Yes | No | No |
| Proprietary Blend | No | No | No | No | No | No | No | No | No | No |
Frequently Asked Questions
Is nattokinase actually a blood thinner?
Yes, in the sense that it has measurable fibrinolytic activity and reduces fibrinogen, factor VII, and factor VIII in human studies. No, in the sense that no clinical trial has compared it head to head with aspirin, warfarin, or a DOAC for preventing strokes or clots. Treat it as a supplement with real biochemical effects, not as a substitute for prescribed anticoagulant therapy.
Does nattokinase clear spike protein or help with long COVID?
No. The only study often cited for this was an in vitro experiment in 2022 (Tanikawa et al.) that used cell cultures in a Petri dish. There are zero human clinical trials of nattokinase for COVID, post-COVID symptoms, or vaccine-related concerns. The in vitro concentrations do not translate to anything achievable through oral supplementation. Anyone selling nattokinase for these uses is ahead of the evidence.
What does FU mean and why does it matter more than mg?
FU stands for fibrinolytic units, the standardized measure of nattokinase enzymatic activity. Clinical trials dosed by FU, not by mg. The benchmark is 2,000 FU per 100mg of NSK-SD extract. A 100mg capsule of generic nattokinase that does not list FU activity could have a fraction of the studied potency, or could be inactivated entirely. Always check the label for FU.
Can I take nattokinase with aspirin or fish oil?
Combining nattokinase with aspirin, other antiplatelets, or therapeutic-dose fish oil increases bleeding risk and is not advised without physician oversight. Even though fish oil at typical supplement doses (1-2g/day) is unlikely to cause clinically significant additive effects, the combination has not been studied for safety. Do not stack blood-thinning agents on your own.
How long until I see effects?
Blood pressure changes in clinical trials appeared over 8 weeks of daily use. Coagulation biomarker shifts (fibrinogen, factor VII, factor VIII) showed up at 2 months in the Hsia 2009 trial. There are no acute, perceptible effects you should expect from a single dose. If you feel something dramatic after one capsule, that is not the nattokinase.
Is NSK-SD really better than other nattokinase brands?
It is the only nattokinase form with most of the published human clinical data. NSK-SD is patented by Japan Bio Science Laboratory, has vitamin K2 removed (relevant if you are on warfarin), and is standardized to 20,000 FU per gram. Other brands may be fine, but they have not been independently shown to match NSK-SD's potency or stability. If a product does not name its source, assume it is generic.
Can nattokinase replace my blood pressure medication?
No. The BP reductions in trials were around 3-5 mmHg, which is meaningful as an adjunct but small compared to first-line antihypertensives. Do not stop or substitute prescribed medication. Discuss with your doctor before adding nattokinase, especially if you are already on antihypertensives or anticoagulants.
Sources
- Kim JY, et al. Effects of nattokinase on blood pressure: a randomized, controlled trial. Hypertension Research. 2008;31(8):1583-8.
- Jensen GS, et al. 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. 2016;9:95-104.
- Hsia CH, et al. Nattokinase decreases plasma levels of fibrinogen, factor VII, and factor VIII in human subjects. Nutrition Research. 2009;29(3):190-6.
- Chen H, et al. Effective management of atherosclerosis progress and hyperlipidemia with nattokinase: A clinical study with 1,062 participants. Frontiers in Cardiovascular Medicine. 2022;9:964977.
- Li X, et al. Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Reviews in Cardiovascular Medicine. 2023;24(8):234.
- Cesarone MR, et al. Prevention of venous thrombosis in long-haul flights with Flite Tabs: the LONFLIT-FLITE randomized, controlled trial. Angiology. 2003;54(5):531-9.
- Gallelli G, et al. Data Recorded in Real Life Support the Safety of Nattokinase in Patients with Vascular Diseases. Nutrients. 2021;13(6):2031.
- Tanikawa T, et al. Degradative Effect of Nattokinase on Spike Protein of SARS-CoV-2. Molecules. 2022;27(17):5405. (In vitro cell culture study only - no human evidence for COVID applications)
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products discussed on this page are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.