Nattokinase Benefits & Side Effects: What The Japanese Enzyme Really Does, And Who Should Skip It

It starts with a Japanese breakfast

Natto is soybeans fermented with a friendly bacteria, Bacillus subtilis natto. People in Japan have eaten it at breakfast for over 1,000 years. As a food it’s a protein-rich fermented staple, but the part researchers kept coming back to was something inside it.

In 1980, Japanese researcher Dr. Hiroyuki Sumi tested more than 170 foods for natural fibrin-clearing activity. Natto came out on top, and the enzyme behind it was named nattokinase.

So what does the enzyme actually do? Just one thing, and everything else follows from it.

The one thing it does, and why it matters

Your body makes a protein called fibrin to help blood clot when you’re cut. Think of it like scaffolding put up for a quick repair: once the repair is done, it has to come down. Your body clears the leftover fibrin away every day, and that clean-up slows with age.

Nattokinase supports your body’s natural fibrin balance. That’s the starting point for every benefit you’ve read about.

Here’s how the benefits follow, one from the next.

What follows from that: the 6 benefits

1. Natural fibrin balance. Every day your body makes some fibrin and clears some away, like a set of scales. With age, the clearing side gets slower. Nattokinase supports that clearing side, so the balance holds the way it used to. Every other benefit starts here.
2. Healthy blood flow. When leftover fibrin is cleared on time, your blood keeps its normal consistency, what doctors call viscosity. Blood at its normal consistency moves easily through your vessels, from the largest to the smallest.
3. Healthy circulation, all the way to your legs and feet. Your legs and feet are the furthest point from your heart, reached through the smallest vessels. That’s where healthy flow matters most, and often where people notice it first.
4. Everyday heart health. Your heart beats around 100,000 times a day, moving your blood through every vessel. Healthy blood flow is part of everyday heart health, which is why the Complex pairs nattokinase with CoQ10 to support heart health.
5. Flexible, healthy arteries. Arteries are the vessels that carry blood away from your heart, and they work best when they stay flexible. By supporting fibrin balance and healthy flow, nattokinase supports the everyday health of those vessels.
6. Healthy cholesterol levels. In the 12-month study of 1,062 adults, cholesterol numbers moved in a healthy direction at 10,800 FU a day. As a daily supplement, it’s support for maintaining healthy cholesterol levels already in the normal range, not a treatment.

Before you think about taking it, here’s who it isn’t for.

Side effects, and who should skip it

Most people take nattokinase without problems. In the 12-month study of 1,062 adults, no noticeable side effects were recorded.

But because it supports your body’s fibrin balance, it isn’t for everyone. Talk to your doctor before taking it if you:

1. Take blood thinners or anti-platelet medication
2. Take blood pressure medication
3. Have a bleeding disorder
4. Are pregnant or nursing
5. Have surgery coming up (stop 2 weeks before)

If none of those apply, there’s only one question left, and it’s the one most people get wrong.

But if this enzyme is so well studied, why do so many people take it and notice nothing? The answer is one number on the label.

Why so many people notice nothing

Here’s what surprised me most when I compared labels. Nattokinase isn’t measured in milligrams. It’s measured in FU (fibrin units).

Here’s the difference in plain terms. Milligrams tell you how much powder is in the capsule. FU tells you how much work the enzyme can actually do. Two bottles with the same milligrams can have very different FU, which is why FU is the number to look for.

Most bottles give you 2,000 to 4,000 FU. In a 12-month study of 1,062 adults, the amount linked to results was 10,800 FU a day. 3,600 FU a day was not.

So if you’ve tried nattokinase before and noticed nothing, the enzyme may not have been the problem. The dose probably was. Which is exactly the number Irmi was built around.

That’s why Irmi gives you the full 10,800 FU

Irmi Nattokinase 10,800 FU Complex was made around that one number: the full 10,800 FU of nattokinase in every serving.

1. 10,800 FU per serving, printed on the front
2. One daily serving: 2 vegetarian capsules
3. Every batch third-party tested, so what’s on the label is in the bottle
4. No natto taste, no natto smell

Alongside the enzyme, every serving includes CoQ10, aged garlic and turmeric to support healthy blood flow and heart health, plus bromelain and pine bark. Six ingredients, one daily routine.

The only real way to know if it’s right for you is to try it. So here’s how to do that without any risk.

Try it for 60 days. If it’s not for you, it’s free.

Week 8 is the fair point to judge any daily supplement. That’s why every order comes with a 60-day money-back guarantee: take it every morning, see how you feel, and if you’re not happy, contact us for a full refund.

Each bottle holds 240 capsules, a 4-month supply, so there’s plenty of time to judge it properly.

Right now you also get a second bottle free with every order.

Buy 1, Get 1 Free

Irmi® Nattokinase 10,800 FU Complex

• The full 10,800 FU dose
• With CoQ10, aged garlic, turmeric, bromelain and pine bark
• Third-party tested, every batch
• 60-day money-back guarantee

Offer ends in 02:30:00

Claim Buy 1, Get 1 Free →

Free bottle with every order while the offer lasts

Taking blood thinners or blood pressure medication? Check with your doctor first.