Nattokinase
What’s New This Month
- Largest trial, now with numbers: In the 3-year NAPS trial, artery wall thickening was 0.013 mm a year on nattokinase and 0.011 on placebo, so the difference may be chance (p=0.31). Serious side effects were 13 of 132 against 15 of 133. 1
- EU wording corrected: The EU allows fermented soybean extract in food supplements for adults, not pregnant or nursing women, up to 100 mg a day. Labels must say people on medication should use it only under medical supervision. We had wrongly cited an age limit before. 2 3
- Health Canada licence: One licensed nattokinase product says not to use it when pregnant or breastfeeding, with products that affect blood clotting, or with a bleeding disorder. Health Canada lists no nattokinase recall between October 2024 and October 2026. 4 5
- FDA warning letter: In May 2026 the FDA cited a seller’s nattokinase claims, including “thins the blood”, as drug claims. 6
Overview
Nattokinase is an enzyme (a protein that speeds a chemical change) taken from natto, a Japanese fermented soybean food. In the lab it breaks down fibrin, the protein that holds clots together.
In 2017 the EU approved a fermented soybean extract as a novel food, up to 100 mg a day for adults. 2
Doses are given in FU (fibrinolytic units), a measure of enzyme strength. Labels claim it dissolves clots and helps circulation, blood pressure, the heart, the brain and long COVID.
How We Researched It
We rate each marketing claim with a modified version of GRADE, the system medical researchers use to say how sure we can be (i.e., high, moderate, low or very low), and check each trial with the Cochrane risk-of-bias tool, which asks whether a study’s design could skew its results. For nattokinase we used 22 evidence records, published 2003 to 2025. We also checked 10 regulators and safety databases.
Research NotesTop three benefits
Circulation and Clot Dissolving GRADE: Low
One 2,000 FU dose raised clot-breakdown markers in 12 men, within the normal range. In 76 people, 8 weeks slowed clotting tests. The 3-year, 265-person NAPS trial found no effect on clotting, blood flow or artery thickening. 7 25 8 1
Bias check: Marker studies were tiny or short. NAPS used a different maker’s product, so its null result is more independent.
Clot Prevention GRADE: Very Low
The only event trial gave 204 high-risk flyers nattokinase plus Pycnogenol (a pine bark extract). None got a leg clot, versus 5 people without it. 16
Bias check: The blend cannot show nattokinase’s own effect. Blinding is unclear, and no one has repeated it.
Long COVID GRADE: Very Low
No human trial exists. Lab studies found it broke down the virus’s spike protein in cells and tiny clots in a dish. 11 26
Bias check: One lab study is a preprint, not yet peer reviewed. Lab results often do not hold up in people.
Benefit Evaluation
| Claim | Claim Verdict | Research Confidence | Supporting Evidence | Safety Risk | Product Quality | FactStack™ Rating |
|---|---|---|---|---|---|---|
| Circulation and Clot Dissolving | TBD | Low | TBD | Real Concern | Inconsistent | Warning |
| Clot Prevention | TBD | Very Low | TBD | Real Concern | Inconsistent | Warning |
| Long COVID | TBD | Very Low | TBD | Real Concern | Inconsistent | Warning |
| Inflammation and Recovery | TBD | Very Low | TBD | Real Concern | Inconsistent | Warning |
| Sinus and Respiratory | TBD | Very Low | TBD | Real Concern | Inconsistent | Warning |
| Gut Health | TBD | Very Low | TBD | Real Concern | Inconsistent | Warning |
| Stroke Recovery | TBD | Very Low | TBD | Real Concern | Inconsistent | Warning |
| Blood Pressure | Doubtful | Low | Doubtful | Real Concern | Inconsistent | Warning |
| Heart Health and Cholesterol | Doubtful | Low | Doubtful | Real Concern | Inconsistent | Warning |
| Cognition | Doubtful | Low | Doubtful | Real Concern | Inconsistent | Warning |
What Sellers Say vs. What Studies Show
| “Dissolves blood clots.” | Single doses moved clotting tests, but only within the normal range. No trial shows fewer clots. The 3-year trial found no effect on clotting. 7 8 |
| “Lowers blood pressure.” | Three short trials together found the top number fell about 3.5 points. That is below the 5 points we count as meaningful. The 3-year trial found no change. 9 8 |
| “Clears plaque from arteries.” | The plaque study had no comparison group and was run by the tablet maker. Controlled trials found no plaque benefit. 10 8 |
| “Breaks down spike protein and helps long COVID.” | Only lab-dish studies exist. No trial has tested it in people. 11 |
| “A safer alternative to aspirin.” | The FDA cited this kind of claim in a May 2026 warning letter. Nattokinase slows clotting, and a brain bleed is on record with aspirin. 6 12 |
| “Each capsule holds what the label says.” | In one 2026 test, 3 of 8 products missed their label for enzyme activity: two low and one high. 13 |
Trial ParametersIf you try it
| Who | No marketed health benefit is established for any group. |
| Dose | No authority dose. Studied at 100 mg (2,000 FU) a day. |
| Ceiling | EU: up to 100 mg a day of fermented soybean extract, for adults only; not for pregnant or breastfeeding women. 2 |
| Duration | Trials ran 8 weeks; the longest data run about 3 years. Health Canada’s licence for one product says to stop 7 days before surgery. 8 4 |
| Form | Enzyme activity is unreliable; 3 of 8 products tested missed the label. No NSF-certified product. 13 |
| Ask First | Blood thinners, or in place of one; bleeding disorders; past brain bleed or recent stroke; pregnancy or breastfeeding; soy allergy; older adults using it alone; a heart, blood-vessel, kidney or liver disorder, or any regular medication. |
How to Take It
| Pick a plan | Trials used 2,000 FU (100 mg) a day, for 8 weeks up to about 3 years. 14 8 |
| Time of day | Not reported. |
| With food | Not reported. |
| What to expect | Nothing you would feel. In short trials the top blood-pressure number fell about 3.5 points; the 3-year trial found no change. 9 8 |
| How to take | Take it on its own, never with or in place of a blood thinner. Health Canada’s licence for one product says to stop 7 days before surgery. 4 |
Works With / Don’t Mix With
✓ Works with
Not reported. No trial shows nattokinase adds to another supplement. Trials of blends with red yeast rice or pine bark cannot show its own effect. 15 16
Your doctor’s plan. High blood pressure and clots have proven treatments. Nattokinase is not a stand-in for them.
⚠ Ask first / don’t mix
Blood thinners and antiplatelets. This means warfarin, DOACs (newer blood thinners), heparin, clopidogrel or daily aspirin. Health Canada’s licence for one product says not to use it with products that affect blood clotting. A brain bleed occurred with aspirin. 4 12
In place of a prescribed blood thinner. One patient swapped it for warfarin after a heart-valve operation and got a valve clot. A 92-year-old using it alone, with no blood thinner, died after a bleed. 17 18
Bleeding disorders or a past brain bleed. The same licence says not to use it with a bleeding disorder. 4 12
Surgery. The same licence says to stop 7 days before. 4
Heart, kidney or liver conditions, or other medicines. Health Canada’s licence for one product says to consult a health care practitioner if you have a cardiovascular, kidney or liver disorder, or if you take any medication. 4
Soy allergy. It is made from soybeans.
Manufacturer Recalls & WarningsLast 36 months, newest first
| Date | Maker / Brand | Product | Action | Src |
|---|---|---|---|---|
| May 2026 | Meta Labs Pharmaceuticals, LLC | Nattokinase Max | FDA warning letter (CMS 725130) cited claims including “thins the blood”, “May Lower Blood Pressure” and “a safer alternative to asperin” [sic] as drug claims. It is not a recall. | 6 |
| Mar 2024 | Kobayashi Pharmaceutical (Japan) | Nattokinase Sarasara-tsubu Gold | According to Japan CAA records (translated), the product was recalled from 22 Mar 2024 because “a link to health damage cannot be ruled out”. The record does not name a cause. | 19 |
Where to Buy
We compare products side-by-side not just on price, but on whether NSF lists the product as NSF/ANSI 173 Contents Certified (an independent lab confirms the label matches the contents), whether it is NSF Certified for Sport, whether USP lists it as USP Verified, and whether the seller says it is manufactured in the USA. We leave out a brand’s products for this supplement when, in the last 36 months, the FDA took action against that brand over this supplement (a Class I or II recall, a warning letter, an import alert or an advisory letter). We also leave out any brand with an FDA Class II recall or warning letter on any product. We also leave out any product named in a California Prop 65 notice or a non-US recall, along with that brand’s products of the same ingredient and form. Brands with other actions stay listed and are marked in the Recall Screen column. Our goal remains to provide you, the Consumer, with the information and data necessary to make an informed purchasing decision. Prices reflected below are static and subject to change.
Ratings above describe the ingredient’s research, not any product listed below.
| # | Retailer | Product | Price | NSF 173 | NSF Sport | USP | Mfg. in USA (per seller) | Recall Screen | Affiliate link |
|---|---|---|---|---|---|---|---|---|---|
| 1 | iHerb | Dr. Murray's, Nattokinase, 2,000 FU, 30 Vegan Capsules | $10.49 | ✓ | ✓ | View on iHerb ↗ | |||
| 2 | iHerb | Force Factor, Nattokinase, 2,000 FU, 90 Vegetable Capsules | $12.99 | ✓ | ✓* | View on iHerb ↗ | |||
| 3 | HerbsPro | Healthy Origins, Natural Nattokinase, 100 Mg, 60 Veg Caps | $12.99 | ✓ | ✓ | View on HerbsPro ↗ | |||
| 4 | iHerb | Nutricost, Nattokinase, 100 mg (2,000 FU), 120 Capsules | $14.95 | ✓ | ✓* | View on iHerb ↗ | |||
| 5 | HerbsPro | Doctors Best, Nattokinase, 2,000 FUS, 90 Veggie Caps | $15.94 | ✓ | ✓ | View on HerbsPro ↗ | |||
| 6 | HerbsPro | Source Naturals, Nattokinase NSK-SD, 200 mg, 30 Caps | $23.79 | ✓ | ✓ | View on HerbsPro ↗ | |||
| 7 | HerbsPro | Now Foods, Nattokinase, 100 mg, 120 Vcaps | $27.91 | ✓ | ✓* | View on HerbsPro ↗ | |||
| 8 | Green's Nutrition | Solaray Nattokinase 30 Veg Caps | $31.09 | ✓ | ✓* | View on Green's Nutrition ↗ | |||
| 9 | Green's Nutrition | Nature's Answer Nattokinase 60 Veg Caps | $59.98 | ✓ | ✓ | View on Green's Nutrition ↗ |
Sources
1. NAPS trial results, NCT02080520: nattokinase and carotid wall thickening (results posted 3 May 2023). ClinicalTrials.gov (API v2), 6 Oct 2026. clinicaltrials.gov/study/NCT02080520
2. Commission Implementing Decision (EU) 2017/115 authorising fermented soybean extract as a novel food ingredient. European Commission (EUR-Lex), 20 Jan 2017. eur-lex.europa.eu/eli/dec_impl/2017/115/oj
3. Implementing Regulation (EU) 2017/2470, Union list of novel foods, consolidated text, entry for fermented soybean extract. European Commission (EUR-Lex), 2 Jul 2026. eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02017R2470-20260702
4. Licensed Natural Health Products Database: NPN 80093953, nattokinase 100 mg (2,000 FU), Provita Nutrition and Health Inc. Health Canada, Licensed 16 Aug 2019. health-products.canada.ca/lnhpd-bdpsnh/info?licence=80093953
5. Recalls and safety alerts database, search for nattokinase (archive included). Health Canada, 6 Oct 2026. recalls-rappels.canada.ca/en
6. Meta Labs Pharmaceuticals, LLC – Warning Letter, CMS 725130. US Food and Drug Administration, 15 May 2026. www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/meta-labs-pharmaceuticals-llc-725130-05152026
7. Kurosawa et al. Single oral dose of nattokinase and clotting and clot-breakdown markers: crossover trial. Scientific Reports, 2015. doi.org/10.1038/srep11601
8. Hodis et al. NAPS: 3-year randomized trial of nattokinase and artery thickening. Clinical Hemorheology and Microcirculation, 2021. doi.org/10.3233/CH-211147
9. Li et al. Nattokinase supplementation and cardiovascular risk factors: meta-analysis of randomized trials. Reviews in Cardiovascular Medicine, 2023. doi.org/10.31083/j.rcm2408234
10. Chen et al. Nattokinase and atherosclerosis and hyperlipidemia: 12-month uncontrolled study. Frontiers in Cardiovascular Medicine, 2022. doi.org/10.3389/fcvm.2022.964977
11. Tanikawa et al. Degradative effect of nattokinase on spike protein of SARS-CoV-2: lab study. Molecules, 2022. doi.org/10.3390/molecules27175405
12. Chang et al. Cerebellar hemorrhage in a patient taking aspirin and nattokinase: case report. Internal Medicine, 2008. doi.org/10.2169/internalmedicine.47.0620
13. Nattokinase supplements review and top picks (updated 16 Mar 2026; product detail behind a paywall). ConsumerLab.com, 16 Mar 2026. www.consumerlab.com/
14. Kim et al. Effects of nattokinase on blood pressure: randomized, controlled trial. Hypertension Research, 2008. doi.org/10.1291/hypres.31.1583
15. Xu et al. Nattokinase with and without red yeast rice in stable coronary disease: randomized trial. Frontiers in Nutrition, 2024. doi.org/10.3389/fnut.2024.1380727
16. Cesarone et al. Prevention of flight-related venous thrombosis with a nattokinase and Pycnogenol product: randomized trial. Angiology, 2003. doi.org/10.1177/000331970305400502
17. Elahi et al. Nattokinase used in place of warfarin after mechanical valve replacement: case report. Proceedings (Baylor University Medical Center), 2015. pubmed.ncbi.nlm.nih.gov/25552810/
18. Ramachandran L et al. Nattokinase-associated hemoperitoneum in an elderly woman: case report. Cureus, 2021. pubmed.ncbi.nlm.nih.gov/35003944/
19. Recall record: Nattokinase Sarasara-tsubu Gold (Kobayashi Pharmaceutical), recall database. Consumer Affairs Agency, Japan, 22 Mar 2024. recall.caa.go.jp/result/detail.php?rcl=00000032058&screenkbn=01
20. openFDA food enforcement records, search for nattokinase (no records). US Food and Drug Administration (openFDA), 6 Oct 2026. api.fda.gov/food/enforcement.json?search=product_description:nattokinase
21. Proposition 65 60-day notice list (CSV export searched for nattokinase). California Office of the Attorney General, 6 Oct 2026. oag.ca.gov/prop65/60-day-notice-list
22. CAERS adverse-event reports naming nattokinase (openFDA food event records; data current to 7 Jul 2026). US Food and Drug Administration (openFDA), 6 Oct 2026. api.fda.gov/food/event.json?search=products.name_brand:nattokinase
23. Response to new dietary ingredient notification 631, Nattolife-Nattokinase Enzyme (Zytex Biotech). US Food and Drug Administration, 17 Mar 2010. downloads.regulations.gov/FDA-2010-S-0665-0234/attachment_1.pdf
24. Novel food register entry: fermented soybean extract. UK Food Standards Agency, 6 Oct 2026. data.food.gov.uk/regulated-products/id/novel-foods/novel-food/fermented-soybean-extract
25. Yoo et al. Nattokinase supplementation and blood clotting times: 8-week randomized trial. Food & Function, 2019. doi.org/10.1039/c8fo02324g
26. Grixti et al. Recombinant nattokinase degrades fibrinaloid microclots: lab study (preprint). bioRxiv, 2024. doi.org/10.1101/2024.04.06.588397
