Nattokinase: The World’s Most Researched Cardiovascular Enzyme

That was over four decades ago. Since then, nattokinase has accumulated one of the most substantial bodies of peer-reviewed cardiovascular research of any enzyme in nutritional medicine. More than 17 human clinical trials. Publications in cardiovascular journals, thrombosis research, and hypertension literature. A consistent safety record. And a mechanism that addresses several of the most important risk factors in cardiovascular disease simultaneously.

And yet most Americans have never heard of it.

Cardiokinase™ is our professional-grade nattokinase formula — and the one I’ve personally recommended to practitioners and customers for over 20 years. Here’s the full picture: what nattokinase actually does, what the research shows, why source and quality matter enormously, and why this enzyme is having a cultural moment unlike anything I’ve seen in my career.

Nattokinase is a serine protease — an enzyme that cleaves peptide bonds — with a specific and remarkable ability to break down fibrin. Fibrin is the structural protein that forms the mesh of a blood clot. It’s created from fibrinogen by the enzyme thrombin during the coagulation cascade, and it’s what holds a clot together once formed.

The reason this matters is that excessive fibrin deposition is a central driver of thrombotic cardiovascular events. When fibrin accumulates faster than the body’s own fibrinolytic system can clear it — as happens chronically with age, inflammation, and metabolic dysfunction — clot risk rises and microvascular circulation is impaired. Nattokinase enhances fibrinolysis: the natural process by which your body breaks down fibrin and clears clots. It does this through multiple converging mechanisms.1

I want to walk through the key human studies here, because they’re more robust than most people realize.

A 2008 randomized controlled trial published in Hypertension Research followed 86 participants with pre-hypertension and stage-1 hypertension over eight weeks. The nattokinase group showed significant reductions in systolic blood pressure (−5.55 mmHg) and diastolic blood pressure (−2.84 mmHg) compared to placebo. The authors noted that the effect size was clinically meaningful — comparable to low-dose pharmaceutical intervention — with no adverse events reported.2

A 2009 Korean study published in Nutrition Research randomized 92 participants to nattokinase or placebo for two months. The nattokinase group showed significantly reduced plasma fibrinogen levels — a key independent predictor of cardiovascular events — as well as reductions in Factor VII and Factor VIII, two coagulation factors associated with thrombotic risk. Importantly, clotting time was prolonged in the nattokinase group, directly demonstrating enhanced fibrinolytic activity.

A 2017 clinical study published in the National Medical Journal of China (Zhonghua Yi Xue Za Zhi) examined nattokinase’s effects on atherosclerotic plaque over 26 weeks in patients with existing carotid artery plaques. Compared to statin monotherapy, nattokinase supplementation produced significantly greater reductions in plaque volume and carotid intima-media thickness — a clinically established surrogate marker for cardiovascular risk. This study attracted significant attention because the comparison group was receiving active pharmaceutical treatment, not placebo.

“The 2017 plaque regression data stopped a lot of people in their tracks — including me. Meaningfully greater reductions in carotid plaque volume than statins alone, over 26 weeks. That’s not a supplement talking point. That’s a trial.”

In 2022 and 2023, nattokinase entered mainstream awareness in a way I have not seen before. Search volume exploded. It became a trending topic in health and wellness communities — discussed in the context of cardiovascular health, long-COVID research, and post-vaccination considerations. I want to address this directly, because the conversation has been both interesting and, in some corners, dramatically overextended.

A 2022 paper published in the peer-reviewed journal Molecules, authored by researchers at Josai University in Japan (with collaborators at Contek Life Science in Taiwan), examined nattokinase’s ability to degrade the SARS-CoV-2 spike protein in vitro. The study used cells expressing the spike protein and incubated them with nattokinase in a lab setting — not a human clinical trial. The findings showed that nattokinase did degrade the spike protein under the experimental conditions used. The paper has been peer-reviewed and published; it is a real study by credentialed researchers.

What that study does not show — and what has been widely misrepresented in non-scientific circles — is that nattokinase supplementation produces measurable degradation of spike protein in living humans, or that it treats or prevents any condition related to SARS-CoV-2 exposure or vaccination. In vitro findings frequently do not translate to clinical outcomes. The enzyme concentrations achieved in a petri dish are not the same as what circulates systemically after oral supplementation. The mechanism is theoretically plausible, but ‘theoretically plausible’ and ‘clinically proven’ are not the same thing.

I mention this because I think intellectual honesty matters more than a trending headline. The research on nattokinase’s cardiovascular mechanisms — fibrinolysis, blood pressure, plaque regression — is robust, replicated, and clinically meaningful. That is the evidence base this product stands on. Any additional discussion of spike protein degradation should be framed as preliminary in vitro research requiring human confirmation, not as established clinical fact.

Not all nattokinase is the same. This is one of the most important things I can tell you about this category.

Nattokinase is produced during the fermentation of soybeans with Bacillus subtilis var. natto — the same traditional process used to make natto for centuries in Japan. The quality of the enzyme depends on the strain of bacteria, the fermentation conditions, the substrate quality, and most critically — how the enzyme is extracted, purified, and standardized.

The standard unit of measurement for nattokinase activity is the Fibrinolytic Unit (FU). This measures the enzyme’s actual enzymatic activity — its ability to cleave fibrin — not just its weight. A product listing ‘100mg nattokinase’ without an FU specification tells you almost nothing about potency. Two products could both claim 100mg and have tenfold differences in actual activity depending on source and processing.

Cardiokinase™ delivers 2,500 FU per softgel — above the 2,000 FU dose used in most of the clinical research. The nattokinase we use is produced through a controlled fermentation process with verified activity at harvest, independently third-party tested for fibrinolytic potency, and free from vitamin K2 — a consideration that matters clinically, as traditional natto contains significant K2 that can interact with anticoagulant medications.

“Nattokinase measured only in milligrams is like measuring coffee in ounces without specifying the roast. The number is real; what it tells you is incomplete.”

Nattokinase has an excellent safety record across 40+ years of use in Japan and a growing body of clinical trials globally. However, because it enhances fibrinolysis, it requires careful consideration in specific populations.

Anyone taking pharmaceutical anticoagulants or antiplatelet medications — warfarin, aspirin, clopidogrel, rivaroxaban, apixaban, or similar — should consult their physician before taking nattokinase. The combination of fibrinolytic enzyme activity with anticoagulant drug activity can produce additive effects on bleeding risk that require medical supervision. This is not a theoretical concern — it’s a real pharmacodynamic interaction.

Similarly, nattokinase is not recommended in the period immediately before or after surgery, or for individuals with active bleeding or clotting disorders. These are standard cautions for any fibrinolytically active compound and are not specific to Cardiokinase™ — they apply to the enzyme class.

For healthy individuals without these contraindications, the clinical trial data supports the use of 2,000 FU daily as a cardiovascular maintenance protocol. The absence of serious adverse events across multiple randomized controlled trials — and across decades of population-level consumption in Japan as traditional natto — provides a meaningful safety foundation.

Cardiokinase™ is not a daily foundation supplement the way magnesium or omega-3 are. It’s a targeted cardiovascular protocol compound — most relevant for individuals with specific cardiovascular risk profiles: those with elevated fibrinogen, family history of cardiovascular concerns, blood pressure in the upper-normal range, high PAI-1, or metabolic markers associated with thrombotic risk.*

For practitioners, it pairs naturally with our Premium Omega-3 Plus — which addresses systemic inflammation upstream of the coagulation cascade — and with Bioactive CoQ10, which supports the mitochondrial function underlying endothelial health. Those three compounds, taken together, address cardiovascular health from three distinct and non-overlapping mechanisms: anti-inflammatory, mitochondrial, and fibrinolytic.

Cardiokinase™ is best taken on an empty stomach, between meals, to maximize systemic absorption and fibrinolytic activity without the interference of food proteins competing for gut absorption. Two capsules per serving, once or twice daily depending on protocol needs.

After 25 years in this industry, I’ve seen a lot of ingredients move from clinical obscurity to mainstream adoption. Very few of them arrive with 40 years of research behind them. Nattokinase is one of the exceptions — and the cultural attention it’s received in recent years, whatever its source, has introduced a genuinely important enzyme to a much wider audience. That’s worth something, even when the conversation gets ahead of the evidence.