Are k2 and nattokinase the same?

Vitamin K2 and nattokinase both come from the same Japanese fermented food — yet they are completely different compounds that work through different mechanisms, on different biological targets, with different clinical applications.

Natto, produced by fermenting soybeans with Bacillus subtilis bacteria, is simultaneously the richest natural dietary source of vitamin K2 (MK-7) on the planet — providing up to 1,765 mcg of MK-7 per 100g serving — and the original source of nattokinase, one of the most studied fibrinolytic enzymes in cardiovascular research. Two remarkable compounds. One food. Entirely different molecules. Understanding the distinction matters, especially when choosing a supplement.

Table of Contents

1. Two Compounds, One Food: What Natto Actually Contains
2. What Is Nattokinase?
3. What Is Vitamin K2?
4. Different Targets: How Each Compound Supports the Heart
5. Why K2 Is Removed From Most Nattokinase Supplements
6. Nattokinase Without K2: What That Means for You
7. Frequently Asked Questions
8. Conclusion

1. Two Compounds, One Food: What Natto Actually Contains

Natto has been consumed in Japan for over 1,000 years, but its nutritional complexity only became clear to scientists in the latter half of the twentieth century. The fermentation of soybeans with Bacillus subtilis natto bacteria produces a cascade of bioactive compounds — and two stand out for their cardiovascular significance: nattokinase, first identified by Dr. Hiroyuki Sumi in 1987, and menaquinone-7 (MK-7), the predominant form of vitamin K2 in fermented foods.

These two compounds emerge from the same biological process but are produced in fundamentally different ways. Nattokinase is a protein — specifically a serine protease enzyme — secreted by the bacteria as a metabolic byproduct of fermentation. Vitamin K2, by contrast, is a fat-soluble vitamin synthesized as part of the bacteria's own cellular machinery. One is a large, folded protein chain with a molecular weight of approximately 27.7 kDa and 275 amino acid residues. The other is a small, lipid-soluble molecule that behaves like a vitamin cofactor. Calling them "the same" is comparable to calling water and motor oil the same because they both come out of an engine.

The confusion is compounded by the supplement market. A 100g serving of traditional natto contains roughly 775 mcg of MK-7 — the highest concentration found in any whole food — alongside nattokinase in amounts roughly equivalent to 2,000 FU (fibrinolytic units). When manufacturers extract nattokinase for supplements, they separate the enzyme from the broader natto matrix. That extraction process is where the K2 question becomes practically important.

2. What Is Nattokinase?

Nattokinase is a fibrinolytic enzyme — meaning its primary biological action is to break down fibrin, the protein scaffold that gives blood clots their structural integrity. It belongs to the serine protease class of enzymes, a family that includes the body's own clot-clearing protein, plasmin. At an equivalent molar dose, nattokinase has been shown to be approximately four times more potent than plasmin in dissolving thrombi in laboratory models — a striking comparison that explains why it attracted serious cardiovascular research interest.

The enzyme works through several complementary mechanisms. It directly cleaves cross-linked fibrin, breaking apart established clots at the molecular level. It also degrades plasminogen activator inhibitor-1 (PAI-1) — a protein that normally limits the body's own clot-clearing system — and enhances the activity of tissue plasminogen activator (tPA), effectively amplifying the endogenous fibrinolytic cascade. This multi-pathway action makes nattokinase distinctively different from either anticoagulant drugs (which prevent clots from forming) or vitamins (which have no fibrinolytic activity whatsoever). BioAbsorb's comprehensive nattokinase guide covers the full mechanism in detail.

Clinical trials have consistently documented modest but statistically significant cardiovascular effects. A randomized, double-blind, placebo-controlled trial of 86 participants with pre-hypertension or stage 1 hypertension (systolic BP 130–159 mmHg) found that 2,000 FU of nattokinase daily for 8 weeks reduced systolic blood pressure by 5.55 mmHg and diastolic blood pressure by 2.84 mmHg compared to placebo. These numbers are modest relative to prescription medications but meaningful for individuals managing borderline-elevated blood pressure without pharmacological intervention. A separate North American trial of 74 hypertensive participants using K2-free nattokinase (100 mg/day for 8 weeks) found both systolic and diastolic reductions, alongside a 15% decrease in von Willebrand factor — a cardiovascular risk marker — in hypertensive participants.

3. What Is Vitamin K2?

Vitamin K2 is a fat-soluble vitamin belonging to the menaquinone family — a group of related molecules distinguished by the length of their side chains. The two forms most relevant to human health are MK-4 (found in animal products, with a short half-life) and MK-7 (found in fermented foods, with a significantly longer half-life that enables extrahepatic distribution). It is MK-7 that makes natto uniquely valuable as a K2 source and that has attracted the most rigorous clinical research. Unlike nattokinase, which is an enzyme catalyzing a specific biochemical reaction, K2 functions as a cofactor — a molecule that activates other proteins by enabling a chemical modification called gamma-carboxylation.

The two proteins K2 most significantly activates are osteocalcin and matrix Gla protein (MGP). Osteocalcin, produced by bone-building cells called osteoblasts, requires K2-dependent carboxylation to bind calcium effectively and support bone mineralization. Only MK-7 has been shown to promote this carboxylation in extrahepatic tissues — including bone — at nutritional doses, making it the most clinically relevant K2 form for bone health. A 3-year randomized trial of 142 postmenopausal women with osteopenia found that 375 mcg of MK-7 daily significantly reduced undercarboxylated osteocalcin (an indicator of K2 insufficiency) compared to placebo — a marker of improved bone-building protein activation.

MGP's role is cardiovascular. It is the only known inhibitor of vascular calcification — the process by which calcium deposits build up in arterial walls, making them stiffer and raising cardiovascular risk. MGP requires K2-dependent carboxylation to become active; without adequate K2, it remains inactive and calcium can accumulate unchecked in the arterial wall. This MGP-activation mechanism is entirely distinct from anything nattokinase does. The enzyme dissolves existing fibrin-based clots; K2 prevents calcium from depositing in vessel walls in the first place — two different stages of cardiovascular risk, addressed by two different compounds.

4. Different Targets: How Each Compound Supports the Heart

Both nattokinase and vitamin K2 are associated with cardiovascular health — but they act on entirely different aspects of it. Nattokinase targets the coagulation-fibrinolysis system: it dissolves fibrin, modulates platelet aggregation, and reduces blood viscosity. Its cardiovascular benefit is most relevant in the context of thrombotic risk — the risk of clots forming in blood vessels and obstructing blood flow. A 2023 meta-analysis of 6 randomized controlled trials with 546 participants confirmed that nattokinase supplementation significantly reduces both systolic and diastolic blood pressure, with the effect likely mediated through reduced blood viscosity and improved endothelial function rather than any calcium-related pathway.

Vitamin K2, by contrast, targets the calcification pathway: it prevents calcium from depositing in arterial walls by keeping matrix Gla protein activated. The clinical evidence for this has grown substantially. A 2026 randomized clinical trial published in JAMA Cardiology — the VitaK-CAC trial, enrolling 180 patients with mild-to-moderate coronary artery disease — found that 360 mcg of MK-7 daily for 24 months resulted in approximately 29% less progression of coronary artery calcification and 42% less calcium mass progression compared to placebo. Biomarker changes confirmed the proposed mechanism: supplementation increased circulating MK-7 and reduced the inactive form of MGP, consistent with enhanced vascular protection. To understand the cardiovascular implications of nattokinase's complementary mechanisms, see how nattokinase supports circulation.

To put this in practical terms: someone with elevated fibrinogen and clotting risk is a candidate for nattokinase. Someone with arterial stiffness or early-stage arterial calcification is a candidate for K2. Someone with both concerns might benefit from both — but taking one does nothing for what the other addresses. A supplement labelled "nattokinase" will not activate MGP or support bone mineralization. A supplement labelled "vitamin K2" will not dissolve fibrin or reduce blood viscosity. These are parallel tools, not alternatives.

5. Why K2 Is Removed From Most Nattokinase Supplements

If both compounds come from natto and both support cardiovascular health, why do most manufacturers remove K2 from nattokinase supplements? There are two reasons, and both are clinically meaningful. The first is biochemical: K2 activates clotting factors in the coagulation cascade. These are the same proteins that nattokinase's fibrinolytic action is designed to counteract. A supplement containing both K2 and nattokinase would, to some degree, be working against itself — nattokinase degrading fibrin while K2 simultaneously activates the proteins that produce it. Separating the two ensures the enzyme's fibrinolytic activity is not undermined.

The second reason is pharmacological safety. Many people who seek nattokinase for cardiovascular support are also on prescription anticoagulants — most commonly warfarin. Warfarin works specifically as a vitamin K antagonist: it blocks the enzyme that recycles vitamin K, reducing the supply of active K available to produce clotting factors. If a patient taking warfarin also consumes significant K2 (as they would from eating natto or taking an unrefined nattokinase extract), the vitamin counteracts the drug, raising clotting risk to dangerous levels. Japan Bio Science Laboratory (JBSL) patented K2 removal technology in 1998 specifically to address this concern, enabling warfarin users to take nattokinase without disrupting their anticoagulation therapy. Their clinical data showed that warfarin patients taking K2-free nattokinase (NSK-SD) actually experienced a more stable coagulation-fibrinolysis profile, not a destabilized one.

This is why the designation "K2-free" on a nattokinase supplement is not a limitation — it is a quality signal and a safety feature. It means the manufacturer has taken the extra step of purifying the enzyme, removing a compound that would both undercut nattokinase's primary mechanism and create unnecessary drug-interaction risk for a significant portion of the target population. For anyone managing cardiovascular conditions who is also on blood thinners, nattokinase's interaction with anticoagulant medications warrants careful reading before starting supplementation.

6. Nattokinase Without K2: What That Means for You

BioAbsorb Nattokinase is formulated to deliver 100 mg of nattokinase per capsule — providing exactly 2,000 FU (fibrinolytic units) of enzyme activity — with all vitamin K2 intentionally removed. This is not an accidental gap in the formulation. It reflects a deliberate choice to maximize the supplement's suitability across a broader population, including individuals who take anticoagulant medications or who separately manage their K2 intake for dosing precision.

The 2,000 FU dose aligns with the clinically studied dose used across the most cited nattokinase trials, including the landmark blood pressure RCT and the North American fibrinolytic study referenced in this article. Each capsule uses DRcaps technology — a delayed-release veggie capsule shell that bypasses stomach acid and delivers the enzyme intact to the small intestine, where absorption occurs. Standard enteric coatings often use phthalates or plasticizers; DRcaps are free of both. The formula is also completely free of gluten, dairy, eggs, nuts, fish, shellfish, and all animal products — 100% vegetarian — and manufactured at a GMP-certified facility in Canada. Every batch is third-party tested for nattokinase activity (confirmed at ≥2,000 FU per capsule), heavy metals, gluten, and microbial contaminants.

For those who want both compounds — nattokinase for fibrinolytic support and K2 for bone and arterial health — the K2-free formulation also makes it straightforward to supplement each independently, giving you full control over the dose of each without one interfering with the other. The 180-capsule supply (a 6-month supply at one capsule daily on an empty stomach) is available at BioAbsorb Nutraceuticals for approximately $49.87 — roughly $0.28 per day.

Frequently Asked Questions

Are nattokinase and vitamin K2 the same supplement?

No. They are fundamentally different compounds that happen to be produced by the same fermentation process in natto. Nattokinase is a protein enzyme; vitamin K2 is a fat-soluble vitamin. They have different molecular structures, different mechanisms of action, and different clinical applications. Taking one does not provide the benefits of the other. A nattokinase supplement will not activate MGP or support bone density — those require K2. A K2 supplement will not dissolve fibrin or reduce blood viscosity — those require nattokinase.

Can you get both nattokinase and K2 from eating natto?

Yes, whole natto contains both compounds, with approximately 775 mcg of MK-7 per 100g in regular natto, alongside nattokinase at roughly 2,000 FU-equivalent activity per typical serving. The practical challenge is that most people outside Japan find natto difficult to tolerate due to its strong smell and fermented texture, and dose-controlling either compound through whole food intake is imprecise. Supplementation allows targeted delivery of whichever compound you need, at a consistent dose.

Does nattokinase have any vitamin K activity?

The nattokinase enzyme itself has no vitamin K activity — it is a protein, not a vitamin. However, unrefined nattokinase extracts made from whole natto may contain trace residual K2 from the fermentation matrix if K2 has not been deliberately removed. Purified, K2-free nattokinase — such as NSK-SD and the formulation used by BioAbsorb — contains no detectable K2. If you are managing your K2 intake carefully (for example, due to warfarin therapy), look specifically for a supplement confirmed to be K2-free.

Should I take nattokinase and K2 together?

For healthy individuals not on anticoagulant therapy, taking both is generally considered safe and may even offer complementary cardiovascular benefits — one addressing fibrin-based clotting risk, the other addressing arterial calcification. However, anyone on warfarin, heparin, or other anticoagulants should not add K2 without first consulting their prescribing physician, as K2 can reduce the drug's effectiveness. For those taking nattokinase alongside blood thinners, using a K2-free formulation is the standard recommendation.

Why would nattokinase have K2 removed if K2 is good for you?

K2 is beneficial in many contexts — particularly for bone density and arterial health — but its presence in a nattokinase supplement creates two specific problems. First, K2 activates clotting factors that nattokinase is designed to counter, partially undermining the enzyme's fibrinolytic effect. Second, K2 is a vitamin K antagonist's primary target: people taking warfarin are specifically instructed to keep K2 intake consistent, and unpredictable K2 in a supplement disrupts that stability. K2's proven cardiovascular benefits are best captured through a separate, controlled K2 supplement rather than an incidental residue in a nattokinase extract.

What is the clinically studied dose for each compound?

For nattokinase, the most consistently used clinical dose is 2,000 FU (fibrinolytic units) daily, corresponding to approximately 100 mg of standardized nattokinase extract — the dose used in the landmark 8-week blood pressure trial and confirmed in the 2023 meta-analysis of 546 participants. For vitamin K2 as MK-7, doses in cardiovascular research have ranged from 90 mcg to 360 mcg daily; the 2026 VitaK-CAC trial that demonstrated 29% less coronary artery calcification progression used 360 mcg daily for 24 months. Bone health trials have generally used 90–375 mcg daily.

Conclusion

Vitamin K2 and nattokinase are not the same — they are two distinct compounds that happen to share a food source. Nattokinase is a fibrinolytic enzyme that dissolves clots and reduces blood viscosity; K2 is a fat-soluble vitamin that activates proteins preventing arterial calcification and supporting bone density. Clinical evidence supports both for cardiovascular health, but through mechanisms that do not overlap. For those seeking the specific benefits of nattokinase — fibrinolysis, blood pressure support, improved blood flow — BioAbsorb Nattokinase delivers 2,000 FU per capsule in a K2-free, DRcaps delayed-release formula — no confusion, no counterproductive compounds, no unnecessary drug-interaction risk.

Research References

1. Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Reviews in Cardiovascular Medicine, Vol. 24 (2023). Meta-analysis of 6 RCTs (546 participants) confirming statistically significant reductions in systolic blood pressure (−3.45 mmHg) and diastolic blood pressure (−2.32 mmHg) with nattokinase supplementation compared to placebo.
2. A Single-Dose of Oral Nattokinase Potentiates Thrombolysis and Anti-Coagulation Profiles. Scientific Reports, Vol. 5 (2015). Double-blind, placebo-controlled crossover study in 12 healthy males demonstrating enhanced fibrinolytic and anticoagulant activity following a single 2,000 FU dose of nattokinase.
3. Effects of Nattokinase on Blood Pressure: A Randomized, Controlled Trial. Hypertension Research, Vol. 31 (2008). Landmark 8-week RCT of 86 participants with pre-hypertension or stage 1 hypertension showing −5.55 mmHg systolic and −2.84 mmHg diastolic blood pressure reduction vs. placebo with 2,000 FU nattokinase daily.
4. Nattokinase: An Oral Antithrombotic Agent for the Prevention of Cardiovascular Disease. International Journal of Molecular Sciences, Vol. 18 (2017). Comprehensive review of nattokinase's fibrinolytic mechanisms, cardiovascular evidence, and safety data from Good Laboratory Practice (GLP)-compliant studies.
5. MK-7 and Its Effects on Bone Quality and Strength. Nutrients, Vol. 12 (2020). Review establishing MK-7 as the only vitamin K homolog capable of promoting gamma-carboxylation of extrahepatic proteins (osteocalcin, MGP) at nutritional doses, due to its superior bioavailability and longer half-life.
6. Highlighting the Substantial Body of Evidence Confirming the Importance of Vitamin K2 as a Cardio-Support Nutrient. Nutrients, Vol. 12 (2020). Review establishing matrix Gla protein (MGP) as the only known inhibitor of vascular calcification and documenting K2's role in MGP activation for cardiovascular protection.
7. Habitual Natto Intake Elevates Serum MK-7 Levels, Enhances Osteocalcin Carboxylation, and Supports Bone Density: A Meta-Analysis of Japanese Evidence. Frontiers in Nutrition, Vol. 12 (2025). Meta-analysis confirming natto as the richest natural source of MK-7 and documenting associations between regular natto consumption and higher circulating MK-7 levels.
8. Intake of Fermented Soybean (Natto) Increases Circulating Vitamin K2 (Menaquinone-7) and Gamma-Carboxylated Osteocalcin Concentration in Normal Individuals. Journal of Bone and Mineral Research, Vol. 15 (2000). Human trial documenting natto's MK-7 content (775–1,765 mcg per 100g) and confirming significant elevation of serum MK-7 and carboxylated osteocalcin with regular consumption.
9. The Effect of Vitamin K2 as MK-7 on Bone Mineral Density and Microarchitecture in Postmenopausal Women with Osteopenia. Osteoporosis International, Vol. 32 (2021). 3-year RCT of 142 postmenopausal women confirming that 375 mcg MK-7 daily significantly reduced undercarboxylated osteocalcin vs. placebo — a marker of improved bone-building protein activation.
10. Two Years of Menaquinone-7 Supplementation and Coronary Artery Calcification: A Randomized Clinical Trial (VitaK-CAC). JAMA Cardiology, Vol. 2026. 2-year, double-blind, placebo-controlled trial in 180 patients with mild-to-moderate coronary artery disease finding 29% less coronary artery calcification progression and 42% less calcium mass progression with 360 mcg MK-7 daily.
11. Vitamin K Supplementation for the Prevention of Cardiovascular Disease: Where Is the Evidence? A Systematic Review. Nutrients, Vol. 12 (2020). Systematic review establishing MGP's role as a K2-dependent inhibitor of vascular mineralization and documenting how K2 deficiency results in impaired carboxylation and increased arterial calcification risk.
12. Consumption of Nattokinase Is Associated with Reduced Blood Pressure and von Willebrand Factor. Integrated Blood Pressure Control, Vol. 8 (2016). Randomized, double-blind, placebo-controlled multicenter North American trial (74 completers) using K2-free nattokinase (100 mg/day, 8 weeks) confirming blood pressure reduction and 15% decrease in von Willebrand factor in hypertensive participants.

About the Author

David Kimbell is a health writer, digital entrepreneur and former aerospace engineer, based in Ottawa, Canada. He loves translating complex science into clear, actionable guidance for consumers seeking evidence-based solutions.

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Important Disclaimers

Medical Disclaimer: This article provides educational information only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement, especially if you have existing health conditions, take medications, or are pregnant or nursing.

FDA/Health Canada Statement: These statements have not been evaluated by the Food and Drug Administration or Health Canada. This product is not intended to diagnose, treat, cure, or prevent any disease.