Nattokinase and Blood Pressure

A single fermented-soybean enzyme has been tested head-to-head against placebo for blood pressure in at least six randomized trials — and the results are more nuanced than most supplement labels suggest.

Nearly half of US adults — 48.1%, or about 119.9 million people — have high blood pressure, and only about 1 in 4 have it controlled. That gap is exactly why nattokinase and blood pressure has become such a heavily searched question. This article walks through what the clinical trials actually found, how the enzyme is thought to work, and where the evidence runs thin.

Table of Contents

• 1. What the Blood Pressure Research Actually Shows
• 2. The Numbers: How Big Is the Effect?
• 3. How Nattokinase Is Thought to Lower Blood Pressure
• 4. Who the Evidence Applies To — and Who It Doesn't
• 5. The Limits of the Evidence
• 6. Safety, Drug Interactions, and When to Be Cautious
• 7. BioAbsorb Nattokinase — A Dose That Matches the Research
• Frequently Asked Questions
• Conclusion
• Research References

1. What the Blood Pressure Research Actually Shows

The interest in nattokinase for blood pressure is not built on marketing alone — it rests on a small but consistent body of randomized, placebo-controlled trials. The most rigorous summary to date, a 2023 systematic review and meta-analysis published in Reviews in Cardiovascular Medicine, pooled 6 eligible trials covering 546 participants and rated the overall study quality as high.

That analysis found nattokinase produced statistically significant reductions in both systolic blood pressure (a mean difference of −3.45 mmHg) and diastolic blood pressure (−2.32 mmHg) compared with placebo, with no notable adverse events reported across the included studies. These are modest numbers — not the dramatic drops a prescription drug can produce — but they were reproducible across different populations, which is what gives them weight. If you want the underlying biology, our companion piece on how nattokinase works covers the enzyme in detail.

2. The Numbers: How Big Is the Effect?

The most cited single study is the first RCT, published in Hypertension Research in 2008. Researchers gave 86 adults with untreated systolic pressure of 130–159 mmHg either 2,000 FU of nattokinase or placebo daily for 8 weeks; 73 completed the protocol. The nattokinase group saw a net systolic drop of 5.55 mmHg and a diastolic drop of 2.84 mmHg versus control, alongside a fall in plasma renin activity of 1.17 ng/mL/h.

A later North American trial is arguably more relevant to Western readers. It tested 100 mg of nattokinase per day (standardized to at least 2,000 FU, with vitamin K2 removed) in 79 enrolled adults with elevated blood pressure. Average diastolic pressure in the nattokinase group fell from 87 to 84 mmHg — and in men specifically dropped from 86 to 81 mmHg (p<0.006), a stronger and more statistically robust effect than in women. To put a 3–5 mmHg systolic reduction in context: population studies suggest even small, sustained drops at this scale can meaningfully shift cardiovascular risk, which is why these findings are taken seriously despite their modest size.

3. How Nattokinase Is Thought to Lower Blood Pressure

Nattokinase is a fibrinolytic enzyme — its best-documented action is breaking down fibrin, the protein scaffold of blood clots. Researchers propose at least two routes by which this could nudge blood pressure down. The first is mechanical: by cleaving fibrinogen and improving how easily blood flows, the enzyme may lower the resistance the heart pumps against.

The second proposed route is hormonal. Laboratory and animal work suggests nattokinase can inhibit angiotensin-converting enzyme (ACE) — the same target as a major class of prescription blood pressure drugs — reducing production of the vessel-constricting hormone angiotensin II. A 2018 mechanism review in Biomarker Insights describes this proposed ACE-inhibiting activity. It's important to be honest here: in human studies, ACE concentrations did not always shift significantly, and reviewers describe the ACE role in people as "controversial." The effect is real but the precise mechanism is still being worked out.

4. Who the Evidence Applies To — and Who It Doesn't

The clearest signal comes from people with pre-hypertension or stage-1 hypertension — the exact group studied in the 2008 trial, where baseline systolic pressure sat between 130 and 159 mmHg. For these readers, the evidence for a small reduction is most directly applicable.

The picture is weaker elsewhere. In a separate study, healthy adults taking 4,000 FU daily saw a slight systolic decline but no diastolic change, and people with established cardiovascular disease saw no significant reduction at all. This matters: nattokinase appears most useful as an early, supportive measure rather than a treatment for advanced disease. Anyone weighing it for broader cardiovascular reasons may find our overview of what nattokinase is and what it does a useful starting point, and the broader cardiovascular research a worthwhile next read once published.

5. The Limits of the Evidence

Honesty about limitations is what separates a useful answer from a sales pitch. The trials are small — the largest pooled analysis still rested on just 546 participants across 6 studies — and most ran for only 8 weeks, so long-term effects are largely unknown. Results have also been mixed depending on dose and population, with no benefit seen in some groups.

There is also the question of magnitude. A 3–5 mmHg systolic reduction is meaningful at a population level but will not, on its own, bring stage-2 hypertension under control. Prescription options such as ACE inhibitors, ARBs, and calcium channel blockers produce stronger, more predictable drops. Nattokinase is best understood as a possible complement to lifestyle measures — not a replacement for prescribed treatment when that treatment is needed.

6. Safety, Drug Interactions, and When to Be Cautious

Across the controlled trials, nattokinase was generally well tolerated, with the meta-analysis reporting no notable adverse events. The real caution is about its blood-thinning nature rather than the supplement itself. Because nattokinase enhances fibrinolysis, Memorial Sloan Kettering notes it may theoretically raise bleeding risk when combined with anticoagulant, antiplatelet, or fibrinolytic drugs.

That means anyone taking warfarin, a DOAC such as apixaban or rivaroxaban, or even daily aspirin should not start nattokinase without medical guidance, since interaction checkers still advise consulting a healthcare provider. The same applies before surgery and for anyone with a bleeding disorder. These blood-thinning considerations deserve a full conversation with your doctor, particularly if you already manage a cardiovascular condition.

7. BioAbsorb Nattokinase — A Dose That Matches the Research

One practical takeaway from the research is that potency should be measured in fibrinolytic units (FU), not just milligrams — milligram weight alone doesn't tell you how active the enzyme is. BioAbsorb Nattokinase delivers 100 mg standardized to 2,000 FU per capsule, the same dose used in the foundational 8-week trial.

It's also intentionally free of vitamin K2 — the same design choice made in the North American trial, where K2 was removed precisely because K2 can interfere with warfarin. The enzyme is delivered in a DRcaps delayed-release vegetarian capsule that protects it from stomach acid without the phthalates found in some enteric coatings, and each batch is third-party tested for nattokinase activity, heavy metals, and contaminants at a Canadian GMP-certified facility. The protocol is simple: one capsule daily on an empty stomach. For most people exploring nattokinase, matching the studied dose and verifying potency in FU is the sensible place to start — and the right dose for your situation is something to confirm with a full dosage guide and your healthcare provider.

Frequently Asked Questions

How much does nattokinase lower blood pressure?

Across pooled trials, nattokinase reduced systolic pressure by about 3.45 mmHg and diastolic by 2.32 mmHg versus placebo. The first dedicated RCT saw a larger 5.55 mmHg systolic drop in people with early-stage hypertension. These are modest, supportive reductions — not the magnitude prescription medications achieve.

How long does it take to see an effect?

The main trials measured blood pressure after 8 weeks of daily use, so that's the realistic window for assessing whether it helps you. Single-dose pharmacokinetic studies show changes in clotting markers within hours, but blood pressure effects appear to build gradually over weeks rather than days.

What dose was used in the studies?

The foundational trial used 2,000 FU (about 100 mg) once daily, and the North American trial used 100 mg of K2-removed nattokinase daily. Potency is best judged in fibrinolytic units (FU) rather than milligrams alone, since FU reflects actual enzyme activity.

Can I take nattokinase with my blood pressure medication?

Possibly, but only with your doctor's input. The bigger concern is overlap with blood thinners or antiplatelet drugs, which can raise bleeding risk. Because nattokinase may have mild additive effects, anyone on prescription cardiovascular medication should review it with a healthcare provider before starting.

Is nattokinase safe for everyone?

It was well tolerated in trials with no notable adverse events, but it isn't right for everyone. People on anticoagulants, those with bleeding disorders, anyone scheduled for surgery, and pregnant or nursing individuals should avoid it unless a physician advises otherwise.

Does removing vitamin K2 matter?

It can. Vitamin K2 promotes clotting and can blunt warfarin's effect, so K2-free nattokinase — as used in the North American trial — avoids that particular interaction and allows clearer dosing. It does not eliminate the general bleeding-risk caution around anticoagulants, however.

Conclusion

The evidence suggests nattokinase can produce a small, consistent reduction in blood pressure — roughly 3–5 mmHg systolic — most clearly in people with early-stage hypertension, with a strong safety record across trials totaling 546 participants. It is a supportive tool, not a substitute for prescribed care. If you'd like to try a dose that matches the clinical research, explore BioAbsorb Nattokinase (100 mg / 2,000 FU) and talk with your healthcare provider about whether it fits your plan.

Research References

1. Effects of Nattokinase on Blood Pressure: A Randomized, Controlled Trial. Hypertension Research, Vol. 31 (2008). First randomized, double-blind, placebo-controlled trial; 2,000 FU daily for 8 weeks reduced systolic pressure by 5.55 mmHg and diastolic by 2.84 mmHg in adults with pre- or stage-1 hypertension.
2. 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, Vol. 9 (2016). 100 mg/day of K2-removed nattokinase lowered diastolic pressure, with the strongest effect in men (86 to 81 mmHg).
3. Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Reviews in Cardiovascular Medicine, Vol. 24 (2023). Pooled 6 RCTs and 546 participants; nattokinase reduced systolic pressure by 3.45 mmHg and diastolic by 2.32 mmHg versus placebo, with no notable adverse events.
4. Nattokinase: A Promising Alternative in Prevention and Treatment of Cardiovascular Diseases. Biomarker Insights, Vol. 13 (2018). Mechanism review describing fibrinogen cleavage and proposed ACE inhibition, while noting the ACE role in humans remains controversial.
5. Inhibition of angiotensin I converting enzyme by subtilisin NAT (nattokinase) in natto. Food & Function, Vol. 3 (2012). Demonstrated ACE-inhibitory activity of nattokinase, supporting a renin-angiotensin pathway for blood pressure reduction.
6. High Blood Pressure Facts. Centers for Disease Control and Prevention (2024). Reports that 48.1% of US adults (119.9 million) have high blood pressure and only about 1 in 4 have it controlled.
7. Nattokinase. Memorial Sloan Kettering Cancer Center — About Herbs database (accessed 2026). Notes theoretical increased bleeding risk when nattokinase is combined with anticoagulant, antiplatelet, or fibrinolytic drugs.
8. Nattokinase and Warfarin Interactions. Drugs.com (accessed 2026). Outlines the bleeding-risk interaction between nattokinase and warfarin and the importance of physician monitoring.

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.