Nattokinase Dosage: How Much Should You Take? (2026)

At a Glance

• Most-studied dose 2,000 FU (fibrinolytic units) once a day, used in the longest trial and in blood pressure trials¹².
• Higher doses Studies have used 4,000–8,000 FU a day, but higher doses haven’t been shown to work better³⁵⁶.
• Timing A single 2,000 FU dose changed clotting markers within 2–8 hours⁷, but no study has tested the best time of day.
• Who shouldn’t take any dose People on blood thinners or daily aspirin, or with bleeding disorders⁹.
• Top pick Nutricost Nattokinase 2,000 FU – the #1 pick in our guide to the best nattokinase supplements: one capsule a day at the 2,000 FU dose used in most trials.

The Short Answer: There’s no official recommended dose of nattokinase, but most human trials used 2,000 FU once a day¹²⁷. That’s the dose used in the 3-year NAPS trial¹ and in a blood pressure trial that found a modest benefit². Doses up to 8,000 FU a day have been studied, but none of the higher-dose studies showed a clear advantage⁵⁶.

On this page

1. Nattokinase Doses Used in Human Studies
2. What Does FU Mean?
3. How Much Nattokinase Should You Take?
4. When and How to Take Nattokinase
5. How Long Can You Take It?
6. Who Should Not Take Nattokinase at Any Dose
7. Final Verdict
8. Frequently Asked Questions

Look for the FU amount on the label rather than milligrams, because enzyme activity can vary between products. If you take a blood thinner or daily aspirin, no dose is considered safe without your doctor’s approval⁹. To compare products, see our guide to the best nattokinase supplements.

Nattokinase Doses Used in Human Studies

Daily dose	How long	Who	What happened
2,000 FU	Single dose	12 healthy men	Clotting markers changed within 2–8 hours, staying in the normal range7
2,000 FU	8 weeks	73 adults with high-normal or stage 1 blood pressure	About 5.6/2.8 mmHg lower blood pressure2
2,000 FU	Median 3 years	265 adults without heart disease	No effect on artery thickening, blood pressure or blood tests1
100 mg	8 weeks	74 adults with high blood pressure	Lower diastolic blood pressure4
4,000 FU (2 × 2,000 FU)	2 months	45 adults, open-label	Fibrinogen and clotting factors fell 7–19%3
6,000 FU	26 weeks	76 adults with carotid plaque	Plaque shrank, but compared with a statin, not placebo5
8,000 FU	6 months	120 adults with narrowed arteries	No improvement in memory scores vs placebo6

What Does FU Mean?

FU stands for fibrinolytic units, a measure of how much fibrin the enzyme can break down in a lab test. It tells you the enzyme’s activity, which is more useful than its weight. Some labels list both FU and milligrams, but compare products by FU.

How Much Nattokinase Should You Take?

For most healthy adults who’ve decided to try it, the best-studied amount is 2,000 FU once a day¹². This is the dose with the most human data, both for possible benefits and for tolerability.

There’s little reason to start higher:

• No added benefit shown. Studies using 4,000–8,000 FU a day weren’t placebo-controlled for the main outcomes or didn’t find a benefit³⁵⁶.
• More effect on clotting. Nattokinase changes clotting tests even at 2,000 FU⁷⁸, so higher doses may add to bleeding risk.
• Case reports. A man taking aspirin had a brain bleed after taking 400 mg of nattokinase a day for a week¹¹.

For what the research shows about benefits, see our guide to nattokinase benefits.

Our Top Nattokinase Pick

Nutricost Nattokinase 2,000 FU

2,000 FU1 capsule a day120 servings

Nutricost gives exactly the 2,000 FU dose used in most trials in one capsule, so you don’t have to split or combine products to hit it, and a bottle lasts about four months. It’s the #1 pick in our guide to the best nattokinase supplements. It hasn’t been tested in its own clinical trial, and it isn’t suitable if you take aspirin or a blood thinner.

Check price on Amazon → See all 7 picks

When and How to Take Nattokinase

• Once a day is typical. Trials gave one daily dose¹².
• Time of day: We didn’t find any study comparing morning and evening doses or taking it with or without food. Follow the label.
• How fast it works: A single dose changed clotting markers within 2–8 hours⁷, but blood pressure changes in trials were measured after 8 weeks².
• Be consistent. If your doctor is monitoring you, don’t change your dose without telling them.

How Long Can You Take It?

The longest trial gave 2,000 FU a day for a median of 3 years¹. A safety study found that 4 weeks of nattokinase at 10 mg per kg of body weight a day was well tolerated in healthy volunteers¹². There’s no data on use beyond about 3 years.

Who Should Not Take Nattokinase at Any Dose

MSK advises these groups to avoid nattokinase⁹:

• People with bleeding or clotting disorders.
• People taking blood thinners or daily aspirin.
• People with a history of deep vein thrombosis.

Also tell your surgeon or dentist if you take it, because it changes clotting tests⁸. See our guides to nattokinase side effects and nattokinase and blood thinners.

Final Verdict

The best-studied nattokinase dose is 2,000 FU once a day. Higher doses of 4,000–8,000 FU haven’t been shown to work better, and because nattokinase affects clotting, a higher dose may add risk. Check the FU on the label, and don’t take any dose if you’re on blood thinners or daily aspirin.

A simple option at the studied dose is Nutricost Nattokinase 2,000 FU. Compare all 7 picks in our guide to the best nattokinase supplements.

Important: This guide is for general information and isn’t medical advice. Talk to your doctor before taking nattokinase, especially if you take any prescription medicine, have a bleeding disorder or are planning surgery.

Frequently Asked Questions

Sources & History12 sources · updated November 11, 2026

References

1. Nattokinase Atherothrombotic Prevention Study: A Randomized Controlled Trial — Clinical Hemorheology and Microcirculation, 2021
2. Effects of Nattokinase on Blood Pressure: A Randomized, Controlled Trial — Hypertension Research, 2008
3. Nattokinase Decreases Plasma Levels of Fibrinogen, Factor VII, and Factor VIII in Human Subjects — Nutrition Research, 2009
4. 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
5. A Clinical Study on the Effect of Nattokinase on Carotid Artery Atherosclerosis and Hyperlipidaemia — Zhonghua Yi Xue Za Zhi, 2017
6. Nattokinase Supplementation for Cognitive Enhancement in Asymptomatic Intracranial/Carotid Stenosis: A Randomized Controlled Trial — Journal of Stroke and Cerebrovascular Diseases, 2026
7. A Single-Dose of Oral Nattokinase Potentiates Thrombolysis and Anti-Coagulation Profiles — Scientific Reports, 2015
8. The Effects of Nattokinase Supplementation on Collagen-Epinephrine Closure Time, Prothrombin Time and Activated Partial Thromboplastin Time in Nondiabetic and Hypercholesterolemic Subjects — Food & Function, 2019
9. Nattokinase — Memorial Sloan Kettering Cancer Center, About Herbs, 2025
10. Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials — Reviews in Cardiovascular Medicine, 2023
11. Cerebellar Hemorrhage Provoked by Combined Use of Nattokinase and Aspirin in a Patient With Cerebral Microbleeds — Internal Medicine, 2008
12. Toxicological Assessment of Nattokinase Derived From Bacillus subtilis var. natto — Food and Chemical Toxicology, 2016

Update history

• November 11, 2026Rewritten with a table of doses used in human studies (2,000–8,000 FU), how to read FU on labels, timing data from a single-dose study, long-term use, and who should avoid it at any dose.