Should I Eat Natto?
Last updated on May 4, 2025
For Informational Purposes Only
The information presented on this website is not a substitute for professional medical advice. Always consult a qualified health professional when deciding on medical care.
Overview
This comprehensive article explores both natto—a traditional Japanese fermented soybean food—and nattokinase, its key bioactive compound. From natto’s centuries-old origins to cutting-edge nattokinase research, we examine the science behind both the whole food and its extracted enzyme, their distinctive cardiovascular benefits, and practical considerations for choosing between traditional food consumption and supplementation. Whether you’re considering natto for its vitamin K2 content, curious about nattokinase’s thrombolytic properties, or navigating the dosing differences between supplements and food sources, this guide provides evidence-based answers to your most pressing questions.
What is natto, and where does it come from?
Natto is a traditional Japanese food made from soybeans fermented with Bacillus subtilis natto, a specific bacterial strain that transforms the beans into a distinctive food with a sticky, stringy texture characterized by cobweb-like filaments when pulled apart with chopsticks. It has been consumed in Japan for centuries as a nutritious food source, commonly eaten for breakfast with rice, and particularly popular in eastern regions of the country. The fermentation process creates not only the unique physical properties but also contributes to natto’s characteristic strong smell and flavor profile that combines elements of ammonia, aged cheese, and a pronounced umami character.
The production of natto involves steaming soybeans and then inoculating them with the B. subtilis natto bacteria, followed by fermentation at warm temperatures. This process yields a food that is rich in protein, vitamins, and minerals, and most significantly, contains the enzyme nattokinase, which has been extensively studied for its potential health benefits.
Nattokinase is measured in Fibrinolytic Units (FU), which quantify the enzyme’s ability to break down fibrin, the protein that forms blood clots. One FU represents the amount of enzyme required to produce a specific degree of fibrin degradation under standardized laboratory conditions.
What is the relationship between natto and nattokinase?
Natto is food made from soybeans while nattokinase is an enzyme found in natto. Specifically, nattokinase is a fibrinolytic enzyme naturally produced by the Bacillus subtilis natto bacteria during soybean fermentation into natto. While nattokinase is the most well-studied active compound in natto, research shows that whole natto extract has stronger antioxidant effects than isolated nattokinase alone, indicating that additional compounds in the fermented food work synergistically with the enzyme. Traditional natto consumption provides nattokinase along with other fermentation products, whereas supplements deliver the purified enzyme in standardized doses.
What are the health benefits of natto and nattokinase?
Cardiovascular Benefits
Nattokinase shows potent fibrinolytic activity, helping to dissolve blood clots more effectively than other enzymes like plasmin in experimental models. This thrombolytic action occurs through multiple mechanisms, including directly degrading fibrin and inactivating plasminogen activator inhibitor-1 (PAI-1), a key inhibitor of the body’s natural clot-dissolving system.
A randomized controlled trial demonstrated that nattokinase supplementation reduced systolic blood pressure by 5.55 mmHg and diastolic by 2.84 mmHg in individuals with pre-hypertension or stage 1 hypertension after 8 weeks. A recent meta-analysis of six randomized controlled trials confirmed these antihypertensive effects while noting that lipid-lowering effects may require higher doses.
Research suggests nattokinase may inhibit platelet aggregation and reduce thromboxane B2 formation, preventing arterial occlusion similar to aspirin but potentially without the gastrointestinal side effects. One clinical study found nattokinase reduced carotid plaque size by 36.6% compared to 11.5% with simvastatin while also modestly improving lipid profiles.
Discover the tests and treatments that could save your life
Get our unbiased and comprehensive report on the latest techniques for heart disease prevention, diagnosis, and treatment.
Anti-inflammatory and Antioxidant Effects
Natto extract offers significant antioxidant protection comparable to or greater than α-tocopherol in preventing lipid oxidation and protecting endothelial cells. Studies show natto extract protects vascular endothelial cells from injury through combined antioxidant and anti-apoptotic effects.
Nattokinase has been shown to disrupt the feedback loop between inflammation, oxidative stress, and coagulation by inhibiting LPS-induced activation of TLR4 and NOX2, reducing reactive oxygen species, suppressing NF-κB pathway activity, and lowering pro-inflammatory cytokines.
Neurological Benefits
Animal studies suggest nattokinase has neuroprotective effects, with pretreatment reducing brain infarct volume by 54-68% in experimental stroke models. These protective effects appear to work through multiple mechanisms, including antiplatelet activity, antioxidant effects, and vascular relaxation via nitric oxide pathways.
Nattokinase has demonstrated amyloid-degrading ability similar to proteinase K, suggesting potential applications in neurodegenerative conditions involving amyloid accumulation. One animal study showed nattokinase reduced key markers associated with Alzheimer’s pathology, including amyloid plaques, acetylcholinesterase activity, and inflammatory.
Metabolic Benefits
A dietary intervention study found that consuming natto with viscous vegetables for two weeks improved insulin sensitivity, reduced total and LDL cholesterol, and lowered oxidative stress markers in overweight individuals with impaired glucose tolerance.
What is the quality of the evidence supporting the purported benefits of natto and nattokinase?
The evidence quality for natto and nattokinase benefits varies significantly by claim. For the reduction of blood pressure, research is relatively strong. A meta-analysis of six studies found significant effects, and a well-designed trial showed blood pressure reductions in hypertensive individuals with no conflicts of interest.
However, many studies have limitations. A large clinical study (1,062 participants) showed clear benefits for atherosclerosis and lipid profiles. But multiple authors of the study were employed by supplement manufacturers, raising potential bias concerns. Several other controlled studies used proper methodology but had small sample sizes or short follow-up periods.
Importantly, one high-quality trial found no benefits for subclinical atherosclerosis of low doses of nattokinase in healthy low-risk individuals over three years, suggesting benefits may require higher doses or be limited to those with more advanced health conditions.
Can consuming natto or nattokinase help reverse coronary heart disease?
Based on the available sources, nattokinase shows promising potential for helping manage existing coronary artery disease, though the evidence for true “reversal” is limited. A randomized controlled trial found that combined nattokinase and red yeast rice supplementation in patients with stable coronary artery disease significantly improved lipid profiles, blood pressure, cardiac enzymes, and antithrombotic markers compared to placebo or either component alone.
Direct evidence for plaque regression comes from a comparative trial where nattokinase reduced carotid plaque size by 36.6%, compared to 11.5% in the simvastatin group, suggesting it may reduce atherosclerotic burden, though carotid plaque is not the same as coronary plaque.
A large retrospective study showed that high-dose nattokinase significantly improved lipid profiles and reduced carotid intima-media thickness and plaque size, with benefits amplified when combined with exercise or vitamin K2.
However, the highest quality randomized controlled trial by Hodis et al. 2021 found that 2,000 FU/day had no significant effect on subclinical atherosclerosis, though this may be due to studying healthy individuals at lower doses than shown effective in other research.
While nattokinase appears to help manage cardiovascular disease by improving lipid profiles, reducing blood pressure, and potentially reducing plaque size, claiming it can “reverse” coronary heart disease goes beyond the current evidence. It may help stabilize or reduce progression of coronary disease, but more studies specifically targeting coronary arteries in CHD patients are needed to determine its full potential.
How are natto and nattokinase sold?
Natto is sold as a traditional food product in Asian markets and grocery stores. It is typically packaged as sticky, fermented soybeans with condiments like mustard and soy sauce. It can be found in the refrigerated section alongside other fermented foods. Nattokinase, by contrast, is marketed as a dietary supplement in capsule or tablet form, sold over the counter without a prescription in health food stores, pharmacies, and online retailers. You can also buy various commercial preparations containing nattokinase, including products like Flite Tabs (containing pinokinase/nattokinase) and combination supplements that pair nattokinase with other compounds like red yeast rice.
Why would I choose to eat natto or take nattokinase supplements regularly?
You might choose natto or nattokinase for cardiovascular health support, particularly if you have elevated blood pressure or risk factors for heart disease. Studies show that daily consumption can reduce blood pressure by approximately 5.55 mmHg systolic and 2.84 mmHg diastolic, while high-dose nattokinase (10,800 FU/day) showed significant improvements in lipid profiles and reduced carotid artery disease. The natural thrombolytic properties may help prevent unwanted blood clots.
Importantly, research shows that lower doses (2,000 FU/day) showed no benefits for subclinical atherosclerosis in healthy, low-risk individuals, while another study found that lower doses were ineffective and only high-dose (10,800 FU) showed clinical benefits. This suggests dosage is critical for effectiveness. You should avoid nattokinase if you take blood thinners like warfarin or have cerebral microbleeds due to increased bleeding risk documented in case reports.
What specific compounds are in natto?
Natto contains a rich array of specific compounds that contribute to its unique properties and potential health benefits. The primary compound is nattokinase, a fibrinolytic enzyme that is unique to natto and has significant thrombolytic activity.
Natto also contains several other important nutrients and bioactive compounds:
—A remarkably high concentration of vitamin K2, particularly the menaquinone-7 (MK-7) form, providing up to 100 times more than most cheeses. A single 50g serving of natto contains approximately 380 μg of vitamin K2.
—Traditional fermented natto contains soy isoflavones, which are phytoestrogen compounds derived from the soybean base.
—The fermentation process produces γ-polyglutamic acid, which gives natto its characteristic sticky texture and may have additional health benefits.
—Probiotic compounds from Bacillus subtilis natto, the specific bacteria used in natto fermentation.
—Antioxidant compounds that have been found to be present in crude extracts from fermented soybeans, though the specific composition may vary.
—The combination of these compounds, particularly the high concentration of bioavailable vitamin K2, nattokinase, and other fermentation products, makes natto unique among fermented soy foods.
How does nattokinase differ from other fibrinolytic enzymes like plasmin or tPA?
Nattokinase is formally a serine protease that was first isolated from natto using saline extraction and demonstrated strong fibrinolytic activity by preferentially cleaving a plasmin-specific substrate. Its activity is inhibited by serine protease inhibitors.
Unlike plasmin and tPA, nattokinase has several distinctive properties. tPA, or tissue plasminogen activator, is a medication primarily used to dissolve blood clots in the treatment of strokes, heart attacks, and other conditions involving blood clots. While plasmin and tPA also degrade fibrin clots, nattokinase degrades fibrin directly and appears to be more potent than plasmin or elastase in animal models of thrombosis. Nattokinase achieved up to 62% flow recovery compared to plasmin in a rat thrombosis model, with less degradation of fibrinogen.
A key difference is that nattokinase uniquely cleaves and inactivates plasminogen activator inhibitor type 1 (PAI-1), significantly enhancing tPA-induced clot lysis, especially in PAI-1-enriched environments. This dual mechanism — direct fibrin degradation plus PAI-1 inhibition — distinguishes nattokinase from traditional thrombolytics.
Additionally, unlike plasmin or tPA which require plasminogen activation, nattokinase directly acts as a fibrinolytic agent and can be taken orally with demonstrated bioavailability in humans, while plasmin and tPA are typically administered intravenously.
How does nattokinase degrade fibrin?
Nattokinase degrades fibrin through a well-characterized enzymatic mechanism. As a serine protease, nattokinase cleaves fibrin directly, degrading thrombi with a relatively selective profile compared to other fibrinolytic enzymes. The enzyme shows inhibition by serine protease inhibitors, confirming its classification.
In terms of mechanism, nattokinase employs a multi-pathway approach to fibrinolysis. Beyond direct fibrin cleavage, it cleaves and inactivates plasminogen activator inhibitor type 1 (PAI-1) at its reactive site, significantly enhancing fibrin clot lysis. This dual action makes it particularly effective in PAI-1-enriched environments.
The enzyme also demonstrates direct action on the coagulation cascade, as nattokinase disrupts heparin-protein interactions, including the binding between heparin and antithrombin. The enzyme binds to heparin with moderate affinity (~250 nM) and requires specific structural requirements for this interaction.
Regarding selectivity, nattokinase shows preferential activity toward fibrin with less degradation of fibrinogen compared to plasmin or elastase. This selectivity profile contributes to its potentially safer fibrinolytic effects, as excessive fibrinogen degradation can lead to systemic bleeding risks.
Don’t become a statistic
Learn the latest strategies to prevent, diagnose, and manage heart disease in our one-of-a-kind report.
Is nattokinase orally bioavailable, and how stable is it through digestion and absorption?
Yes, nattokinase is orally bioavailable and remains active after gastrointestinal transit. In an animal study, fibrinolytic activity was detected in plasma after oral administration of nattokinase, suggesting it survives digestion and enters circulation.
In humans, oral intake of nattokinase led to increased fibrin/fibrinogen degradation products and shortened euglobulin lysis time, confirming systemic fibrinolytic effects.
These results were supported by researchers who found oral nattokinase suppressed thrombosis in rats, consistent with functional absorption.
Taken together, these studies indicate that a meaningful portion of nattokinase remains bioactive and is absorbed into circulation after oral ingestion.
What is the therapeutic dose of nattokinase (in FU/day) needed to impact cardiovascular health?
The therapeutic dose of nattokinase for cardiovascular health varies considerably across different studies, but a clear pattern emerges from the research.
For blood pressure reduction, 2,000 FU per day for 8 weeks was effective in reducing systolic and diastolic blood pressure in individuals with pre-hypertension or stage 1 hypertension.
However, higher doses appear necessary for managing atherosclerosis and hyperlipidemia. A large retrospective study found that 10,800 FU/day was effective in significantly improving lipid profiles and reducing carotid intima-media thickness and plaque size, while lower doses were inadequate for these outcomes.
For thrombosis prevention, doses in the 2,000-6,000 FU range appear useful. A randomized trial using 6,000 FU/day for 26 weeks demonstrated significant carotid plaque reduction of 36.6% compared to 11.5% in the simvastatin group.
The single published randomized controlled trial by Hodis et al. 2021 found that 2,000 FU/day had no significant effect on carotid intima-media thickness, arterial stiffness, blood pressure, or other cardiovascular biomarkers, suggesting that higher doses may be required for subclinical atherosclerosis prevention.
Based on these sources, optimal therapeutic doses appear to be:
—2,000 FU/day: Effective for blood pressure management
—6,000 FU/day: Effective for plaque reduction
—10,800 FU/day: Required for optimal lipid profile improvement
—Below 2,000 FU/day: Generally insufficient for cardiovascular benefits
How does nattokinase interact with aspirin, statins, or blood pressure medications—synergy, duplication, or danger?
Nattokinase demonstrates both beneficial and potentially dangerous interactions with other cardiovascular medications, depending on the specific drug and clinical context:
Statin synergy: Nattokinase appears to have complementary rather than duplicative effects with statins. In a comparative trial, nattokinase significantly reduced carotid plaque size by 36.6%, compared to 11.5% with simvastatin, suggesting different mechanisms of action and potential for synergy.
Blood pressure medication compatibility: The combination appears beneficial. A major retrospective study found that coadministration of aspirin or vitamin K2 enhanced nattokinase’s benefits in managing atherosclerosis and hyperlipidemia. Additionally, a trial found that nattokinase combined with red yeast rice was safe even alongside conventional heart medications like those for blood pressure.
Aspirin – serious bleeding risk: Despite some benefits, the combination poses significant danger. A case report documented cerebellar hemorrhage provoked by combined use of nattokinase and aspirin in a patient with cerebral microbleeds. This led to the conclusion that nattokinase may increase the risk of hemorrhagic stroke, especially when combined with other antithrombotic agents.
Clinical safety observations: A large safety study evaluating nattokinase in 153 patients with vascular diseases found no adverse drug reactions or interactions, including when used as adjunct therapy following anticoagulant treatment.
Is there a lack of high-quality research on natto and nattokinase?
Several reviewers note significant limitations in the available research on nattokinase. A 2014 review from the pharmacy literature specifically stated that clinical trials are necessary to substantiate nattokinase’s efficacy and safety, emphasizing that human clinical trial data are limited.
A more recent meta-analysis attempted to address this gap but found only six randomized controlled trials met inclusion criteria, with a total of just 546 participants across all studies. The authors highlighted that “the field lacks large, independent, high-quality RCTs confirming NK’s efficacy in clinical endpoints.”
Another narrative review from 2023 identifies that many cited studies are small, open-label, or animal-based, noting that despite comprehensive findings, the evidence base lacks sufficient high-quality human trials.
The highest quality study to date, a randomized, double-blind, placebo-controlled trial, found no significant benefits from nattokinase supplementation for cardiovascular outcomes in healthy individuals. However, this single negative study highlights the scarcity of rigorous trials rather than conclusively settling nattokinase’s effectiveness, particularly given its methodological choices of using relatively low doses and studying a healthy population.
Overall, while there is substantial mechanistic and preliminary evidence for nattokinase’s benefits, the research field suffers from a lack of large-scale, multicenter randomized controlled trials with cardiovascular endpoints as primary outcomes.
Is there a systematic bias in Western medicine against Eastern-origin therapies like nattokinase or fermented foods?
There is evidence of potential systemic bias against nattokinase and traditional fermented foods in Western medical systems. Several researchers explicitly note a reluctance within established medical institutions to embrace these approaches.
Multiple reviews highlight potential sources of bias. One narrative review from 2023 notes that nattokinase’s benefits undermine the exclusive reliance on statins, aspirin, and conventional antihypertensives, suggesting that pharmaceutical interests and conventional cardiology may resist its adoption due to “lack of patentability and regulatory approval as a drug.”
Another comprehensive review suggests that these findings challenge pharmaceutical dominance in several areas, including the market share of mainstream antithrombotic, antihypertensive, and lipid-lowering drugs. It notes that “major pharmaceutical companies and some cardiologists may be biased against it due to financial and institutional conflicts.”
The resistance appears to stem from both commercial and conceptual barriers. A 2002 review explicitly states that nattokinase challenges pharmaceutical hegemony in cardiovascular care, proposing “a low-cost, over-the-counter supplement as an alternative to prescription thrombolytics,” with critics potentially including “conservative hematologists” or “regulatory bodies wary of insufficiently validated therapies.”
Despite these systemic challenges, some prominent academic institutions have conducted research that appears designed to evaluate nattokinase through conventional pharmaceutical paradigms. The highest-quality randomized controlled trial by Hodis et al. 2021 from USC, while conducted with rigorous methodology and no reported conflicts of interest, used a dose of 2,000 FU/day—which other research suggests is too low for cardiovascular benefits—and studied healthy, low-risk participants. This illustrates how well-intentioned Western research may inadvertently create methodological bias by applying pharmaceutical testing standards that may not be appropriate for traditional dietary compounds typically consumed long-term by at-risk populations rather than as short-term interventions by healthy subjects.
Where can I buy natto in the US?
Natto can typically be found at Japanese grocery stores like Mitsuwa, Nijiya, or Marukai, and some Asian supermarkets like H-Mart or 99 Ranch Market. Some natural food stores and larger supermarkets with substantial Asian food sections may also carry it. It’s usually stocked in the refrigerated section.
Nattokinase supplements and freeze-dried forms are available at health food stores, vitamin shops, and online retailers like Amazon. Specialty Japanese online grocers often carry frozen and shelf-stable varieties. Black bean natto and ready-meals are primarily found through Japanese import websites and some specialty Asian grocers.
How much does natto cost?
In the US, natto typically costs $2-4 for a 3-pack of small portions (40-50g each) at Asian grocery stores. Prices vary by region and store type. Supplement forms like nattokinase tablets generally range from $15-30 for a month’s supply.
Conclusion
The relationship between natto and nattokinase reveals a fascinating balance between traditional wisdom and modern science. While natto provides nattokinase alongside other beneficial compounds like vitamin K2 and antioxidants, purified nattokinase supplements offer standardized dosing for specific therapeutic purposes. The key insight is that higher doses of nattokinase (6,000-10,800 FU/day) show significant cardiovascular benefits, while lower doses may be ineffective—making supplement choice particularly important. Neither natto nor nattokinase should be combined with anticoagulants due to serious bleeding risks. For those seeking natural approaches to cardiovascular health, both options offer promise: natto as a nutrient-dense traditional food, and nattokinase as a targeted therapeutic supplement.