Nattokinase And The Appeal of Natural Clot Busters

In the age of social media health trends, nattokinase, an enzyme derived from fermented soybeans, has gained popularity as a "natural" way to prevent blood clots and heart attacks. Proponents claim it can dissolve dangerous clots and keep arteries clear. They even claim that it can remove plaque from the inside of your arterial walls. They even claim it removes calcium from your arteries!

But when we look at the actual science, a very different picture emerges. To understand why nattokinase falls short, we need to compare it to proven clot-busting drugs and, most importantly, to humble aspirin, a medication that costs pennies and has decades of rock-solid evidence behind it.

What Is Nattokinase?

Nattokinase is an enzyme that comes from natto, a traditional Japanese food made by fermenting soybeans with bacteria called Bacillus subtilis. A Japanese researcher discovered it in 1987 and found that it could break down fibrin, the protein that forms the "mesh" holding blood clots together.

Humans Are Not Rats And Test Tubes

In laboratory dishes and animal studies, nattokinase does show clot-dissolving activity. One rat study found that nattokinase restored 62% of blood flow in blocked arteries, compared to only 16% with plasmin (the body's natural clot dissolver). That sounds impressive, until you realize that what works in a test tube or a rat doesn't always work in humans. This never panned out in human studies.

There are no large human trials proving that nattokinase prevents heart attacks, strokes, or death. It remains classified as a dietary supplement, not an approved medication. The FDA does not regulate it the same way it regulates drugs, which means there's no guarantee of purity, potency, or effectiveness. It may even be contaminated and dangerous.

What About Streptokinase?

To understand what a real clot-busting drug looks like, let's look at streptokinase. This protein comes from streptococcus bacteria (the same type that causes strep throat) and was one of the first "thrombolytic" drugs used to treat heart attacks.

Unlike nattokinase, streptokinase has been tested in massive clinical trials. It works by activating plasminogen, a substance already in your blood, which then turns into plasmin and dissolves clots. Think of it as flipping a powerful switch that turns on your body's clot-dissolving machinery.

Streptokinase is given through an IV in the hospital during a heart attack emergency. It must be administered quickly, ideally within hours of symptoms starting, to save heart muscle from dying.

The biggest point, is that it actually works!

The ISIS-2 Trial: A Landmark Study

The most important evidence for streptokinase comes from the ISIS-2 trial, published in 1988. This massive study enrolled over 17,000 heart attack patients across 417 hospitals. Patients were randomly assigned to receive streptokinase, aspirin, both, or neither.

The results were striking:

• Streptokinase alone reduced deaths by 25% (from 12.0% to 9.2%)
• Aspirin alone reduced deaths by 23% (from 11.8% to 9.4%)
• Both together reduced deaths by 42% (from 13.2% to 8.0%)

Here's the surprising part, streptokinase, a powerful IV clot-dissolving drug given in the hospital, did not beat aspirin. A simple pill that costs a few cents performed just as well as an expensive, hospital-administered medication.

This wasn't because streptokinase is weak. It's a proven, life-saving drug. The remarkable finding is that aspirin is incredibly effective. The two drugs work through completely different mechanisms: streptokinase dissolves existing clots, while aspirin prevents new clots from forming by stopping platelets from sticking together. When combined, their benefits add up, which is why the combination was so much better than either alone.

So why do the online grifters try to sell you nattokinase?

Medfluencers can't sell you "aspirin" on their supplement website, even though it beat the much stronger version of nattokinase, which is streptokinase. Why? Aspirin is cheap and they can't make money on it!

Why Aspirin Beats Streptokinase And Nattokinase

Aspirin's advantages over nattokinase are overwhelming:

1. Proven effectiveness: Aspirin has been tested in trials involving hundreds of thousands of patients. The ISIS-2 trial alone showed a 23% reduction in death. Nattokinase has no comparable evidence.
2. Cost: Aspirin costs pennies per dose. Nattokinase supplements can cost $20-40 per month, with no proven benefit.
3. Safety data: We know aspirin's risks, mainly bleeding and stomach irritation—because it has been studied extensively. Nattokinase's long-term safety profile is largely unknown.
4. Consistency: Aspirin is manufactured under strict pharmaceutical standards. Nattokinase supplements vary widely in quality and potency.
5. Guideline support: Every major cardiology organization recommends aspirin for appropriate patients. None recommend nattokinase.

The Hierarchy of Clot-Busting Drugs

To put nattokinase in perspective, consider the hierarchy of proven thrombolytic drugs:

At the top are modern clot-busters like alteplase (tPA), reteplase, and tenecteplase. These are given in hospitals for acute heart attacks and strokes. The GUSTO-I trial showed that alteplase is 14% better than streptokinase at preventing death.

Streptokinase sits below these newer drugs but remains valuable, especially in countries where cost is a concern. It's proven to save lives. We no longer use this in the United States because we have much more effective alternatives.

Aspirin, while not a clot-buster in the traditional sense, prevents clots from forming in the first place. For prevention, it's remarkably effective and far more practical than IV medications.

Where does nattokinase fit? Nowhere in this hierarchy. It has not been proven to work in humans for any cardiovascular outcome. It exists in a separate category: supplements with theoretical benefits but no clinical proof.

The Danger of Unproven Alternatives

Choosing nattokinase over aspirin isn't just a waste of money, it could be dangerous. People who take nattokinase instead of proven medications may be giving themselves a false sense of security while their cardiovascular risk goes unaddressed.

Taking nattokinase is the equivalent of taking nothing at all. If you want to reduce your risk, take a baby aspirin. But since it costs almost nothing, medfluencers aren't going to recommend it, since they can profit from it.

Additionally, nattokinase can interact with blood thinners like warfarin, potentially causing dangerous bleeding. Because it's not regulated as a drug, people may not realize they need to tell their doctors they're taking it.

Stick With What Works

The science is clear. Streptokinase is a powerful, proven clot-dissolving drug, but even it couldn't beat aspirin in the ISIS-2 trial. Nattokinase, despite its appeal as a "natural" alternative, has never been proven to prevent heart attacks, strokes, or death in large human trials. It certainly doesn't "unclog your arteries" as many claim.

For cardiovascular prevention, aspirin remains one of the most effective, affordable, and well-studied medications available. Before taking any supplement claiming to protect your heart, talk to your doctor about proven options. When it comes to your health, evidence matters more than marketing.

References:

Randomised Trial of Intravenous Streptokinase, Oral Aspirin, Both, or Neither Among 17,187 Cases of Suspected Acute Myocardial Infarction: ISIS-2. ISIS-2 (Second International Study of Infarct Survival) Collaborative Group. 
Lancet. 1988.

Nattokinase: Production and Application. 
Applied Microbiology and Biotechnology. 2014. Dabbagh F, Negahdaripour M, Berenjian A, et al.