Best Nattokinase (2026): 6 Top Bottles Checked Against the Trials
By Erin Rose Updated October 13, 2026 Methodology
Buy Doctor’s Best Nattokinase 2,000 FUs. One capsule gives the 2,000 FU a day the trials used, for $0.14 a day. Half of the 6 top sellers give 2 to 5 times that, and no trial shows more is better.
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Our pick: the trial dose
- Per day
- $0.14on Amazon
- Nattokinase
- 2,000 FU
- Pills
- 1 capsule
- Vitamin K2
- Removed
Our take
One capsule gives the 2,000 FU a day used in the main trials, with nothing else added. Its label says vitamin K2 is removed; that is why we pick it over Nutricost, which costs a cent or two less a day but says nothing about K2. A bottle of 270 lasts about 9 months, at $0.14 a day.
The label
Testing record
Not found on any testing list we check.
Not on NSF’s supplement list (searched October 13, 2026). No outside lab named.
Lowest cost at the trial dose
- Per day
- $0.12on Amazon
- Nattokinase
- 2,000 FU (100 mg)
- Pills
- 1 capsule
- Lasts
- 120 days
Our take
The cheapest way to take 2,000 FU a day of the 6 we checked: $0.12. One capsule, nattokinase only. It does not say whether vitamin K2 was removed.
Testing record
Not found on any testing list we check.
Not on NSF’s supplement list (searched October 13, 2026). The bottle says “third party tested” but names no lab.
Sold by Amazon, no vitamin K
- Per day
- $0.28at 1 capsule
- Nattokinase
- 2,000 FU (100 mg)
- Pills
- 1 capsule
- Vitamin K
- None
Our take
Amazon sells and ships it, and its label says it has no vitamin K. Its label also has the plainest warning of the 6: do not use it with blood thinners such as aspirin, warfarin or heparin. It costs about twice as much a day as our pick.
The label
Testing record
Not found on any testing list we check.
Not on NSF’s supplement list (searched October 13, 2026).
Check with your doctor first if you take a blood thinner, including daily aspirin, or have surgery coming up. Nattokinase acts on blood clotting. Who should not take it.
Every bottle we checked, cheapest a day first
These are the 6 best-selling nattokinase bottles on Amazon. We read each label and priced a day’s dose. The trials used 2,000 FU a day.
| Bottle | FU a day | Trial dose | Per day |
|---|---|---|---|
| Nutricost 1 capsule a day. Says “third party tested,” no lab named | 2,000 | Matches | $0.12 |
| Doctor's Best 1 capsule a day. Says vitamin K2 is removed | 2,000 | Matches | $0.14 |
| NOW 1 capsule a day. Sold by Amazon; says it has no vitamin K | 2,000 | Matches | $0.28 |
| Double Wood 2 capsules a day. Says “third-party tested,” no lab named | 4,000 | 2× | $0.33 |
| Micro Ingredients 3 capsules a day. Also: CoQ10, turmeric, garlic, grape seed, dandelion, bromelain, pine bark | 10,000 | 5× | $0.37 |
| Luma Nutrition 2 capsules a day. Says “third-party tested,” no lab named | 4,000 | 2× | $0.67 |
- Doctor’s Best ($0.14) is our pick: the trial dose in one capsule, and it says vitamin K2 is removed.
- Nutricost ($0.12) is the cheapest way to get the trial dose.
- Micro Ingredients ($0.37) is the top seller. It packs 5 times the trial dose into 3 capsules, plus a blend of 7 other ingredients.
- Double Wood ($0.33) and Luma ($0.67) give twice the trial dose in 2 capsules.
Is more FU better? No trial says so
FU (fibrinolytic units) measures how fast the enzyme breaks down fibrin, a clot protein, in a lab test. It is the number to compare. Milligrams are not: brands use different FU per mg.
- The trials used 2,000 FU. The 3-year U.S. trial gave 2,000 FU a day, and the two blood pressure trials used 2,000 FU capsules.
- Half the top sellers give more. Double Wood and Luma give 4,000 FU. Micro Ingredients gives 10,000 FU.
- The one study we found of 10,000-plus FU had no comparison group. In a 2022 study from China, 1,001 of its 1,062 people took 10,800 FU a day, and it reported lower cholesterol. It only looked back at records, had no placebo group, and five authors worked for the company that made the tablets.
Labels are not always right, either. ConsumerLab tested 8 nattokinase brands in 2025; only 5 had about the strength their label claimed. Two had much less and one had much more (ConsumerLab). The brands it tested included Doctor’s Best, NOW, Nutricost and Double Wood, but its free summary does not say which failed. None of the 6 here is on NSF’s supplement list.
Does nattokinase work?
Not for what most people buy it for. The research is small and mixed.
- The biggest trial found nothing. In NAPS, 265 healthy adults (half of them over 65) took 2,000 FU a day or a placebo for about 3 years. Artery thickening, artery stiffness and blood pressure did not differ between the groups.
- Blood pressure may drop a little. Two 8-week trials gave 2,000 FU capsules to people with high blood pressure. In both, the bottom number fell about 3 points; in one, the top number fell about 6. Pooled across 6 small trials, the drop was about 3 points on top and 2 on the bottom.
- It does act on clotting. In 12 healthy young men, one 2,000 FU dose changed several clotting markers for a few hours, though all stayed in the normal range. That is why the safety warning matters.
Our take: the proof is thin. If you try it, the dose studied is 2,000 FU a day. It does not replace any prescribed medicine, and no trial shows it prevents heart attacks or strokes. The blood pressure trials lasted 8 weeks; ask your doctor after that whether it is worth going on.
Who should not take nattokinase
- People on blood thinners, including daily aspirin and prescription anticoagulants. Memorial Sloan Kettering warns it may raise bleeding risk with these drugs (MSK). In one reported case, a patient taking aspirin had a bleed in the brain after 7 days of 400 mg of nattokinase a day.
- Anyone with a bleeding disorder or surgery coming up. Tell your surgeon or dentist you take it.
- Anyone tempted to use it instead of a prescribed blood thinner. Never swap one for the other.
- People allergic to soy. All 6 labels list soy.
About vitamin K2: natto, the food, is rich in vitamin K2, which can weaken warfarin. Many nattokinase supplements remove it. Doctor’s Best says K2 is removed, and NOW says it has no vitamin K; the other four labels do not say. If you take warfarin, the advice above still applies: ask your doctor before you take any of them.
What about “spike protein detox”?
Some doctors promote nattokinase, with bromelain and curcumin, as a way to clear COVID or vaccine spike protein. No trial has tested it. Their own 2023 paper says the plan has not been tested in randomized controlled trials and that no treatment claims can be made. One of the authors works for a company that sells a nattokinase product (FactCheck.org).
Who should buy which
- You want the trial dose, simplyDoctor’s Best Nattokinase 2,000 FUs
One capsule, 2,000 FU, vitamin K2 removed, $0.14 a day. Check price
- You want the lowest costNutricost Nattokinase 2,000 FU
The same 2,000 FU in one capsule, $0.12 a day. Check price
- You want it sold by Amazon, with no vitamin KNOW Nattokinase 100 mg
2,000 FU a capsule, no vitamin K, $0.28 a day at one a day. Check price
- You take a blood thinnerNone, unless your doctor says yes
The bleeding risk is the reason. Ask before you start.
More: omega-3 for triglycerides, citrus bergamot, garlic and CoQ10. This page is not medical advice.
Questions
What is the best nattokinase supplement?
Doctor's Best Nattokinase 2,000 FUs. One capsule gives the 2,000 FU a day used in the trials, the listing says vitamin K2 is removed, and it costs $0.14 a day on Amazon. Nutricost has the same dose for $0.12 a day.
How much nattokinase should I take a day?
The main trials used 2,000 FU a day. That is usually 100 mg, but check the FU number, because brands use different ratios. No trial has shown that more works better.
What does nattokinase do?
It is an enzyme from natto, a Japanese fermented soybean food. In the lab it breaks down fibrin, a protein in blood clots. In small trials it lowered blood pressure by about 3 points. The largest and longest trial, 3 years in 265 adults, found no effect on artery thickening or blood pressure.
Is nattokinase safe?
Do not take it with blood thinners, including aspirin, or before surgery, unless your doctor says it is OK. Memorial Sloan Kettering warns it may raise bleeding risk. A 2008 case report described a patient on aspirin who had a bleed in the brain after a week of nattokinase. Never use it in place of a prescribed blood thinner.
Does nattokinase remove spike protein?
No trial has tested that. The doctors who promote it as a “spike protein detox” wrote that it has not been tested in randomized controlled trials and that no treatment claims can be made.
Sources
- Labels: NIH Dietary Supplement Label Database 302692 (Doctor’s Best Nattokinase 2,000 FUs), 313866 (NOW Nattokinase 100 mg) and 315687 (Double Wood 4,000 FU). Amazon listings and label photos, read October 17, 2026: Doctor’s Best B0051M9DKU, Nutricost B09LRLLGCZ, NOW B000F3QFTW, Double Wood B0B6CQ9ZVJ, Luma B0CKZL4CXM, Micro Ingredients B0G2N6TFRD.
- Testing: NSF/ANSI 173, “nattokinase”, searched October 13, 2026. ConsumerLab, Nattokinase Supplements Review (free summary, updated March 16, 2026).
- Hodis HN, et al. “Nattokinase atherothrombotic prevention study: A randomized controlled trial.” Clinical Hemorheology and Microcirculation. 2021. PubMed 33843667 (NAPS)
- Kim JY, et al. “Effects of nattokinase on blood pressure: a randomized, controlled trial.” Hypertension Research. 2008. PubMed 18971533
- Jensen GS, et al. “Consumption of nattokinase is associated with reduced blood pressure and von Willebrand factor, a cardiovascular risk marker: results from a randomized, double-blind, placebo-controlled, multicenter North American clinical trial.” Integrated Blood Pressure Control. 2016. PubMed 27785095
- 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. PubMed 39076715
- Kurosawa Y, et al. “A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles.” Scientific Reports. 2015. PubMed 26109079
- 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. PubMed 36072877
- Chang YY, et al. “Cerebellar hemorrhage provoked by combined use of nattokinase and aspirin in a patient with cerebral microbleeds.” Internal Medicine. 2008. PubMed 18310985
- Memorial Sloan Kettering Cancer Center. About Herbs: Nattokinase (bleeding risk with blood thinners).
- FactCheck.org. Posts Push Unproven ‘Spike Protein Detoxification’ Regimen, September 21, 2023.