From ancient Japanese kitchens to modern clinical trials β everything you need to know about the enzyme that dissolves blood clots and clears arteries.
Two landmark studies show what nattokinase can do. Here's what the science found β in plain English.
Researchers gave over 1,000 people a daily dose of 10,800 FU of nattokinase for a full year. The results were impressive: artery plaque buildup and high cholesterol were effectively managed. The lower dose of 3,600 FU/day did not work β only 10,800 FU/day made a real difference. This dose was safe and well-tolerated. Adding vitamin K2 and aspirin led to even better outcomes.
Artery plaque size decreased by up to 36% β clearer arteries, better blood flow, and lower risk of heart attack and stroke.
Researchers tracked nearly 30,000 Japanese men and women for 16 years, comparing health outcomes based on how much natto they ate. The results were clear: more natto meant fewer deaths from heart disease and stroke.
In simple terms: People who ate the most natto had a quarter fewer deaths from heart disease, nearly a third fewer stroke deaths, and a third fewer deaths from clot-based strokes compared to those who ate the least.
Japan has one of the highest life expectancies on Earth β the average Japanese person lives to 85 years, several years longer than people in many Western countries. While many factors play a role (diet, healthcare, lifestyle), natto has been a daily part of the Japanese diet for over 1,000 years, especially in regions with the longest lifespans.
Japan leads the world in longevity β 5.5 years longer than the USA and 3.4 years longer than the UK.
Based on the clinical research, the effective daily dose is:
The biggest study used 10,800 FU/day with strong results. The lower dose of 3,600 FU/day did not work. Look for capsules with 5,000 FU each β take 1 or 2 daily. Always check for FU on the label, not just milligrams.
Before it became a supplement, nattokinase was breakfast. To understand this enzyme, you need to know the food it comes from β and the country that's eaten it every morning for a thousand years.
NattΕ is a traditional Japanese food made from whole soybeans fermented with the bacterium Bacillus subtilis var. natto. It's sticky, stringy, strong-smelling, and very much an acquired taste. And yet this humble fermented food contains one of the most powerful natural blood-clot-dissolving enzymes ever found.
The most popular origin story dates to the 11th century. During a war in northeast Japan (1051β1062 AD), a samurai commander was marching his army. Boiled soybeans for horse feed were packed into rice straw bales. The horses' body heat, moisture, and naturally present bacteria created perfect fermentation conditions. When the bales were opened, the soybeans had transformed β covered in white film, connected by sticky threads.
For hundreds of years, natto was just food. Then in 1980, Dr. Hiroyuki Sumi placed a small piece of natto on an artificial blood clot in a lab dish. Within 18 hours, the clot had completely dissolved. He had discovered an extremely powerful enzyme β one that breaks down fibrin, the protein mesh that holds blood clots together. He published his findings in 1987 and named it "nattokinase."
"I had searched over 173 different foods for a natural agent that could dissolve thrombus, and I found it in nattΕ."Dr. Hiroyuki Sumi β University of Chicago, 1980
Fermented soybeans become a daily breakfast food in northeast Japan.
The word "nattΕ" first appears in a Japanese court diary.
NattΕ dissolves blood clots at the University of Chicago Medical School.
First scientific paper identifying and naming nattokinase.
Clinical trial shows nattokinase significantly reduces blood pressure.
1,062-participant study shows plaque reduction; separate lab study shows spike protein degradation.
Multiple systematic reviews confirm blood pressure and cardiovascular benefits.
Unlike most supplements that work through just one pathway, nattokinase works through four different mechanisms at the same time. Its main target is fibrin β the protein that forms the scaffolding of blood clots.
Dissolves the protein mesh holding blood clots together. Its most powerful action.
Converts inactive pro-urokinase into active urokinase, boosting your body's own clot-dissolving system.
Increases tissue plasminogen activator, which creates plasmin β another clot-breaking enzyme.
Destroys the protein that normally blocks your body from dissolving clots.
Beyond clots, nattokinase also breaks down triglycerides, inhibits the same enzyme targeted by statin drugs, and helps the liver clear LDL cholesterol faster.
Nattokinase isn't measured in milligrams β it's measured in FU (Fibrinolytic Units), which tells you how active the enzyme is, not how much it weighs. A label saying "100mg nattokinase" without FU is meaningless. Always look for FU.
In 2022, Japanese researchers at the University of Tokushima published a peer-reviewed study in Molecules examining whether nattokinase could break down the SARS-CoV-2 spike protein β the protein the virus uses to enter human cells.
SARS-CoV-2 spike protein sits on cell surfaces and helps the virus enter cells.
Nattokinase was added to cells expressing the spike protein.
The spike protein was broken down in a dose- and time-dependent manner.
When cells with spike protein were treated with nattokinase, the spike protein on the cell surface was significantly reduced. The effect was dose-dependent (more nattokinase = more degradation) and time-dependent (longer exposure = more breakdown). Importantly, this happened at concentrations that were not toxic to cells.
The researchers concluded that nattokinase shows potential for inhibiting SARS-CoV-2 infection by breaking down the spike protein. This is a laboratory finding β human clinical trials are still needed. But the results are promising, especially combined with nattokinase's ability to dissolve fibrin-based blood clots, a known complication of COVID-19.
Study: Tanikawa et al. (2022) β "Degradative Effect of Nattokinase on Spike Protein of SARS-CoV-2" β Molecules, 27(17), 5405. Published by MDPI, peer-reviewed.
Here's what the evidence says across key areas of heart health.
A 2023 review of multiple clinical trials found nattokinase reduced systolic blood pressure by 3.45 mmHg and diastolic by 2.32 mmHg vs placebo. Earlier trials confirmed reductions in just 8 weeks.
A 2024 trial of 178 patients found nattokinase combined with red yeast rice was most effective β reducing triglycerides, cholesterol, and blood pressure while raising HDL. The 1,062-participant study confirmed improvements at 10,800 FU/day.
The 1,062-participant study found significant reductions in artery wall thickness and plaque size after 12 months at 10,800 FU/day, with improvement rates from 66.5% to 95.4%.
Natto has been eaten in Japan for centuries. Toxicology studies found no problems at 100x typical human doses. Clinical trials up to 12 months reported no notable side effects. Don't take with blood thinners without medical advice.
| Study | Participants | Duration | Key Findings |
|---|---|---|---|
| Chen et al., 2022 Frontiers in CV Medicine | 1,062 | 12 months | 10,800 FU/day reduced plaque; 3,600 FU/day ineffective |
| Natto Observational 16-year follow-up | 29,079 | 16 years | 25% lower CV death, 33% lower ischemic stroke death |
| Tanikawa et al., 2022 Molecules (MDPI) | Lab study | β | Nattokinase degraded spike protein dose- and time-dependently |
| Kim et al., 2008 Hypertension Research | 86 | 8 weeks | Significant diastolic blood pressure reduction |
| Liu et al., 2024 Frontiers in Nutrition | 178 | 90 days | NK + red yeast rice most effective combo |
| Meta-Analysis, 2023 Reviews in CV Medicine | 546 (6 RCTs) | Varied | Confirmed BP reduction (-3.45 / -2.32 mmHg) |
Research means nothing if your supplement doesn't contain what it says. Independent testing has uncovered a serious quality problem.
In 2025, SORA Laboratories independently tested 5 popular nattokinase brands purchased from retail stores. 4 out of 5 failed to deliver their claimed potency, with some falling over 33% short.
Source: SORA Laboratories, 2025. Products purchased from retail channels.
Claimed 4,000 FU per 2 capsules
Claimed 4,000 FU per capsule
Claimed 4,000 FU per 2 capsules
Claimed 4,000 FU per 2 capsules
Claimed 5,000 FU per capsule
Every result above comes from an official SORA Labs Certificate of Analysis:
See the third-party testing results and dive deeper into the science.
SORA Labs results broken down β see which brands passed and which failed independent testing.
A deep dive into the clinical evidence behind nattokinase supplementation.
How nattokinase works at the molecular level and why it differs from pharmaceutical blood thinners.
Clinical evidence for effects on blood pressure, cholesterol, and arterial health.
The history of natto consumption and the decades of studies that followed Dr. Sumi's discovery.
Always check for FU, not just milligrams. A label with only milligrams and no FU tells you nothing about the enzyme's real strength.
Look for third-party testing. Independent lab results from SORA Labs, ConsumerLab, USP, or NSF are the only way to confirm what's actually in the bottle.
Consider the dose. The biggest trial used 10,800 FU/day. Look for 5,000 FU per capsule as a minimum.
Check for vitamin K. Some products contain vitamin K2 from fermentation, which can interfere with blood-thinning medications like warfarin. Look for "vitamin K2 removed" or "NSK-SD" labels.
Nattokinase is an enzyme from nattΕ, a Japanese fermented soybean food. It's a serine protease that cuts protein chains, especially fibrin β the protein that forms blood clots. Discovered in 1980 by Dr. Hiroyuki Sumi.
FU stands for Fibrinolytic Units β a measure of enzyme activity, not weight. This is the real measure of potency. A label with only milligrams and no FU is incomplete.
The largest trial (1,062 people, 12 months) found benefits at 10,800 FU/day but 3,600 FU/day didn't work. Look for 5,000 FU capsules, take 1-2 daily. Consult a healthcare professional first.
Nattokinase has natural blood-thinning properties. Don't combine it with anticoagulant medications without your doctor's guidance. Stop before surgery.
A 2022 lab study showed nattokinase can degrade the SARS-CoV-2 spike protein in a dose- and time-dependent way. Promising, but human clinical trials are still needed.
Natto has been eaten daily in Japan for 1,000+ years. Modern toxicology studies found no issues at 100x typical doses. Clinical trials up to 12 months reported no notable side effects.
Nattokinase is an enzyme sensitive to heat, moisture, and storage. The supplement industry has less regulation than pharmaceuticals. Independent testing is the only way to know what you're getting.
Medical Disclaimer: This page is for educational purposes only and is not medical advice. Nattokinase has not been evaluated by the MHRA, FDA, or any regulatory body for treating disease. Consult a healthcare professional before starting any supplement, especially if you take blood thinners or have a medical condition.