Table of Contents
Key Takeaways:
Researchers have investigated nattokinase for several aspects of cardiovascular health, including blood pressure, fibrinolytic activity, and cardiovascular risk markers.
A 2023 meta-analysis of six randomized controlled trials found that nattokinase supplementation was associated with modest reductions in blood pressure. That said, overall research results on nattokinase and cardiovascular health are somewhat mixed.
Nattokinase is a dietary supplement, not a replacement for prescribed cardiovascular medication or medical care.
Nattokinase is an enzyme derived from natto, a traditional Japanese food made from fermented soybeans. Nattokinase has been studied for its potential effects on blood flow, fibrin, blood pressure, and other cardiovascular markers. As nattokinase research emerges, an increasing number of people seeking holistic cardiovascular health support have asked their cardiologists about incorporating nattokinase into their daily routines.
So, what do cardiologists say about nattokinase? Nattokinase has some interesting research behind it, including human clinical trials. At the same time, the evidence is not yet strong enough to place nattokinase alongside established cardiovascular medications or standard medical therapies.
That distinction is particularly important for anyone wondering why doctors don't generally recommend nattokinase. In many cases, it’s less about doctors being opposed to the supplement and more about the standards of evidence physicians use when making official treatment recommendations.
What Is Nattokinase?
Nattokinase is an enzyme that naturally occurs during the fermentation process of natto. Natto is produced by fermenting soybeans with Bacillus subtilis, a healthy form of bacteria, and has been eaten in Japan for centuries.
Researchers became interested in nattokinase largely because of its fibrinolytic properties. Fibrinolysis is the body's natural process for breaking down fibrin, a protein involved in forming blood clots.
Laboratory research has demonstrated that nattokinase can interact with fibrin and pathways associated with coagulation and fibrinolysis. However, demonstrating a biological mechanism in a laboratory is different from proving that taking a nattokinase supplement prevents heart attacks, strokes, or other cardiovascular events in people.
What Do Cardiologists Say About Nattokinase?
There’s no single position shared by every cardiologist. Some physicians might be open to discussing nattokinase as a dietary supplement, especially when a patient is interested in complementary approaches to cardiovascular wellness. Others may discourage its use based on limited clinical evidence, possible interactions with a patient's daily medications, or a patient's individual medical history or needs.
From an evidence-based cardiology perspective, the central issue is that nattokinase doesn’t yet have the type of large-scale clinical evidence available for established cardiovascular therapies. Researchers have conducted randomized controlled trials involving nattokinase, but the evidence base remains relatively small.
A 2023 systematic review and meta-analysis evaluated randomized controlled trials investigating nattokinase and cardiovascular risk factors. Six studies containing 546 participants were included in the quantitative analysis. Researchers found that nattokinase supplementation was associated with an average reduction in systolic blood pressure of approximately 3.45 mmHg and an average reduction in diastolic blood pressure of approximately 2.32 mmHg compared with control interventions.
Why Don't Doctors Recommend Nattokinase?
It can be difficult to understand why doctors don't recommend things like enzymes or supplements that show promise in clinical trials.
If the outcomes of trials are so wonderful, why wouldn't doctors suggest things like nattokinase to their patients? The answer is somewhat complicated. Great early clinical trial outcomes are only an important first step. There's a lot more to consider and a lot more information that still needs to be uncovered and interpreted before doctors can make an official recommendation.
The Clinical Evidence Is Still Limited
Doctors generally prefer treatments supported by multiple large, well-designed clinical trials. Research on nattokinase has produced some encouraging findings, but many studies have been relatively small. The 2023 meta-analysis, for example, found only six randomized controlled trials suitable for quantitative analysis, totaling 546 participants.
That's enough evidence to justify continued research, but considerably less than the evidence available for many established cardiovascular treatments.
Cardiologists also care about more than whether a supplement changes a laboratory measurement. Ideally, cardiovascular studies determine whether an intervention meaningfully reduces major outcomes such as heart attack, stroke, hospitalization, cardiovascular death, or overall mortality. Nattokinase hasn't been researched extensively enough to provide a complete picture of many of these vital metrics.
Research Results Have Been Mixed
Some studies have produced encouraging results. For example, an eight-week randomized controlled trial involving people with untreated prehypertension or stage 1 hypertension found that nattokinase supplementation was associated with reductions in systolic and diastolic blood pressure compared with placebo.
A considerably longer randomized controlled trial followed 265 adults without clinical cardiovascular disease for a median of three years. Participants received either 2,000 fibrinolytic units of nattokinase or a placebo. Researchers found no significant difference in the progression of carotid intima-media thickness or carotid arterial stiffness, two measurements used to evaluate subclinical atherosclerosis. They also found no significant effect on blood pressure or the laboratory measurements studied.
Mixed results make physicians hesitant to make broad recommendations.
Supplements Are Regulated Differently From Medications
Nattokinase is treated differently in conventional medicine due to regulatory requirements. Dietary supplements do not go through the same FDA premarket approval process required for prescription medications. The FDA does not approve dietary supplements for safety and effectiveness before they are marketed. Manufacturers and distributors are responsible for ensuring that their products comply with applicable safety and labeling requirements.
This doesn't necessarily mean that dietary supplements are automatically ineffective or unsafe. It only indicates that the standards for review and approval are so different between medications and supplements that doctors are usually more comfortable with medications that have been rigorously tested and approved.
The Bottom Line: What Do Cardiologists Say About Nattokinase?
The available research on nattokinase provides reasons for scientific interest, particularly regarding nattokinase's fibrinolytic properties and possible modest effects on blood pressure. Several randomized trials have produced encouraging results, and researchers continue to investigate its potential cardiovascular applications.
At the same time, evidence remains limited and sometimes contradictory. The issue isn't necessarily that nattokinase has been proven ineffective. Rather, the evidence just hasn't yet reached the level generally required to make it part of standard cardiovascular care.
For people interested in complementary cardiovascular support, nattokinase may be worth discussing with a healthcare professional. It should be approached as a dietary supplement and not as a replacement for prescribed medications, emergency treatment, or individualized medical care.
If you and your cardiologist agree that you’re a good candidate for nattokinase supplementation, Toku Flow is formulated with a clinically relevant dose of nattokinase. Toku Flow utilizes 10,800 FU of nattokinase per serving, matching the dose used in Chen et al. (2022), the largest published human nattokinase study to date. This study followed over 1,000 participants for 12 months and found that 10,800 FU/day was associated with measurable improvements in atherosclerosis-related markers, while a lower 3,600 FU/day dose showed no significant effect. Ask your doctor before incorporating Toku Flow into your daily wellness routine.
FAQs
Why don't doctors recommend nattokinase?
Some doctors may be comfortable discussing nattokinase, but it is not a standard cardiovascular treatment. The primary reasons include limited large-scale human research, mixed results between clinical trials, lack of definitive evidence showing reduced heart attacks or strokes, potential bleeding interactions, and the different regulatory standards applied to dietary supplements.
Do cardiologists consider nattokinase a blood thinner?
Nattokinase is studied for effects on fibrinolysis and coagulation, but it should not be considered interchangeable with a prescription anticoagulant. Because it may influence blood clotting and potentially increase bleeding risk, anyone taking anticoagulant or antiplatelet medication should speak with a healthcare professional before using it.
Can I take nattokinase instead of a statin?
Nattokinase should not be used as a replacement for a prescribed statin. Current clinical evidence does not establish nattokinase as an equivalent cholesterol-lowering therapy, and randomized research has not demonstrated a consistent lipid-lowering effect. If you are experiencing side effects or have concerns about statin therapy, discuss alternative treatment options with your healthcare provider rather than discontinuing medication independently.
Does nattokinase prevent heart attacks or strokes?
Current evidence does not establish that taking nattokinase prevents heart attacks or strokes. Studies have investigated intermediate cardiovascular measures such as blood pressure, coagulation markers, and subclinical atherosclerosis, but large clinical trials demonstrating reductions in major cardiovascular events are lacking.
*The information provided in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives. This content has not been evaluated by the Food and Drug Administration and is not intended to diagnose, treat, cure, or prevent any disease.
Sources:
Effects of nattokinase on blood pressure: a randomized, controlled trial | PubMed
Nattokinase atherothrombotic prevention study: A randomized controlled trial | PubMed
