THE PROMISE
Award-winning potency. Endorsed by the discoverer himself.
Cardiokinase® is the only Nattokinase brand endorsed by Dr. Hiroyuki Sumi — the scientist who originally discovered Nattokinase. Its HTNK-J® formula delivers the highest fibrinolytic activity of any Nattokinase on the market. Practitioner-trusted since 1999. Zero fillers. Zero compromise.
Heart Health
Nattokinase supports healthy blood clotting activity and cardiovascular function — helping the heart work efficiently every single day.*
Blood Flow
Supports the breakdown of fibrin in the bloodstream, promoting smooth, fluid circulation throughout the entire body.*
Blood Pressure
Research suggests Nattokinase may support healthy blood pressure already within the normal range — without harsh stimulants.*
Dr. Sumi Endorsed
The only Nattokinase brand personally endorsed by Dr. Hiroyuki Sumi — discoverer of Nattokinase. Manufactured in Japan and imported exclusively by Pure Prescriptions.
How It Compares
Compare The Difference
Experience the difference with award-winning Cardiokinase® — the highest-potency nattokinase on the market, the only legitimate formula of its kind, and the only one endorsed by its original discoverer, Dr. Hiroyuki Sumi.
“Nattokinase”
Products
(Equivalent to 2500 F.U.)Unknown
(generally recognized as safe)Unknown
The only nattokinase endorsed by Dr. Hiroyuki Sumi — its original discoverer
Customer Reviews
Tried, tested,
truly loved.
The Origin
We were there
at the beginning.
In 2001, Pure Prescriptions brought a doctor-only Nattokinase — one available exclusively in select physicians’ offices — direct to consumers for the first time. It was a conviction born from our belief that professional-grade nutrition shouldn’t require a referral.
By 2002, we had placed it under our own label: Cardiokinase® — formulated with a patented Nattokinase strain developed by Dr. Hiroyuki Sumi himself, manufactured in Japan and imported directly. In 2008, Dr. Sumi developed HTNK-J®, an even more potent strain, and worked directly with Pure Prescriptions and Dr. Devin Ryerson to bring it exclusively to our formula. The following year, Nutrition Business Journal recognized Cardiokinase® with a Product Merit Award.
Today, the market is flooded with imitations — enzymes not derived from authentic natto, with unverified activity levels, and no scientific backing. There is only one Nattokinase exclusively endorsed by its discoverer. It’s in every bottle of Cardiokinase®. We are the only brand Dr. Sumi trusts.
Product Merit Award
2009
A History of Firsts
First to Consumers
Pure Prescriptions brings a doctor-only Nattokinase — previously available only in select physicians’ offices — direct to consumers for the first time. No one else was doing anything like it.
Cardiokinase® is Born
We placed Nattokinase under our own label and named it Cardiokinase®, formulated with a patented strain developed by Dr. Hiroyuki Sumi, the enzyme’s original discoverer — manufactured in Japan and imported exclusively for Pure Prescriptions.
A More Potent Strain
Dr. Sumi develops HTNK-J® — a new, stronger strain of Nattokinase — and works directly with Pure Prescriptions and Dr. Devin Ryerson to bring it exclusively to Cardiokinase®. The most potent Nattokinase ever produced.
Nutrition Business Journal Award
Cardiokinase® wins the Nutrition Business Journal Product Merit Award — recognising it as the most trusted and clinically validated Nattokinase available, exclusively endorsed by its discoverer, Dr. Sumi.
Buyer Beware
The Nattokinase market is rife with counterfeit and adulterated products. Many brands sell enzymes that are not derived from authentic fermented natto, contain unverified fibrinolytic activity, or have never been third-party tested. Only HTNK-J® — the formula in Cardiokinase® — is endorsed by Dr. Hiroyuki Sumi, the scientist who discovered Nattokinase in 1980. Accept no substitute.
Your Protocol
When to take it,
and why it matters
Nattokinase works cumulatively and is best taken with food. For maximum benefit, Dr. Sumi's research recommends one serving at night before bed — when the body's natural cardiovascular maintenance occurs.
Morning
Take 1 softgel with your morning meal. Starting your day with Cardiokinase® allows the enzyme to begin supporting fibrinolytic activity during your most active hours.
Why it works
HTNK-J® Nattokinase begins supporting healthy circulation and blood pressure regulation.
Afternoon
A second softgel at lunch maintains steady enzyme levels throughout the day. Cardiovascular health is built through consistency — not single doses.
Why it works
Sustained fibrinolytic activity supports healthy blood flow across your busiest hours.
Evening
For best results, take one serving at night before bed. The body performs much of its cardiovascular maintenance overnight — making this the most clinically supported time to dose.
Why it works
Nattokinase supports the body's natural overnight fibrinolytic processes for deep cardiovascular recovery.
Suggested Use
Simple softgels. Clinically dosed.
Small, easy-to-swallow softgels. Take with food or as directed by your healthcare professional.
What's Inside
What's inside,
and why it matters.
Nattokinase HTNK-J®
HTNK-J® is a next-generation Nattokinase strain developed by Dr. Hiroyuki Sumi — the enzyme's original discoverer — in collaboration with Pure Prescriptions. It delivers 2,500 Fibrinolytic Units per softgel, the relevant measure of how much fibrin the enzyme can actively break down. Manufactured in Japan.*
Kurashiki, Japan · HTNK-J® strain · Third-party verified · 2,500 FU per softgel · K2-free extraction · Non-GMO.
Kurashiki, Japan · HTNK-J®
Softgel (Soybean Oil)
Nattokinase requires protection from stomach acid to reach the small intestine intact. The softgel format — using soybean oil as a lipid carrier — shields the enzyme through the stomach and supports absorption at the intestinal level.*
Gelatin · Glycerin · Soybean oil · Glycerin fatty ester · Beeswax. No artificial additives.
Softgel · Soybean Oil · Enhanced Stability
Dr. Devin Ryerson
Founder & Chief Curator · Est. 1999Why It Matters
Built by someone with
personal stakes in it.
Devin started Pure Prescriptions in 1999 after battling Hodgkin's Lymphoma and losing his father to leukemia. That experience made him the most stubborn kind of formulator — one who refuses to ship anything he wouldn't take himself.
Every ingredient here earned its place through clinical evidence, third-party testing, and that same personal lens — the five collagen types, the organic fruiting-body mushrooms, the co-factors. Nothing is decorative.
"Pure Prescriptions has always been more personal than corporate. Built by family. Still independent."
Our StoryYour Journey
What to expect
Nattokinase works cumulatively. Here’s what thousands of customers experience over time.*
Week 1–2
Circulation & Warmth
Many customers notice a sense of better circulation within the first two weeks of consistent use.*
Fibrinolytic Activity Begins
Week 4
Energy & Clarity
Supports healthy oxygen-carrying efficiency in the blood, which supports healthy energy levels and mental clarity throughout the day.*
Cardiovascular Efficiency
Week 8
Heart Health Markers
Consistent users often report a greater sense of overall cardiovascular wellness at their regular checkups. Blood pressure tends to stay within the already-healthy range.*
HTNK-J® Cumulative Effect
Week 12
Full Cardiovascular Support
At 12 weeks, the cumulative fibrinolytic benefits of daily Nattokinase use are well-established. This is where the long-term cardiovascular support adds up.*
Full Protocol Benefit
Results are best with daily use · Most customers see full benefits by week 12
Results vary from person to person.
The Science Behind Cardiokinase®
Discovered in 1980.
Still the standard.
Still the only endorsed brand.
Dr. Hiroyuki Sumi discovered Nattokinase while researching fibrinolytic enzymes in fermented foods. After decades of study, he endorses only one brand — Cardiokinase® — because it alone meets his exacting standards for purity, potency, and safety.
- Only brand endorsed by Dr. Hiroyuki Sumi, Nattokinase discoverer
- HTNK-J® formula
- highest fibrinolytic activity available
- Vitamin K2-free — consult your physician before taking any nattokinase supplement if you are taking anticoagulant medications
- Small softgels designed for daily compliance and maximum absorption
Cardiovascular Wellness
Have Questions?
Everything you need to know
Honest answers — no marketing spin.
Cardiokinase® is the only nattokinase brand personally endorsed by Dr. Hiroyuki Sumi — the Japanese scientist who discovered nattokinase in 1980. This endorsement is not extended to any other brand. Cardiokinase® uses HTNK-J®, a Nattokinase strain developed by Dr. Hiroyuki Sumi in collaboration with Pure Prescriptions.
Take 1–3 softgels daily with food or as directed by your healthcare professional. For best results, take one serving at night before bed to support your body’s natural overnight cardiovascular maintenance.
If you are taking anticoagulant medications such as warfarin, clopidogrel, or aspirin, please consult your physician before taking any nattokinase supplement. Nattokinase has fibrinolytic properties that may interact with anticoagulant therapy.
HTNK-J® is a next-generation Nattokinase strain developed by Dr. Hiroyuki Sumi — the enzyme’s original discoverer — in collaboration with Pure Prescriptions. Cardiokinase™ Nattokinase HTNK-J is listed at 100 mg (25 IU) per softgel. Manufactured in Japan.
Many users begin noticing improved circulation and cardiovascular comfort within 2–4 weeks of consistent daily use. Nattokinase works cumulatively — consistent daily use over 30–90 days typically yields the most meaningful results.
Yes. Every batch is third-party tested for purity and potency. A full Certificate of Analysis is available. We hold our suppliers to the same standards we hold ourselves — no contaminants, and label-accurate enzyme activity verified independently.
Complete Your Protocol
Better together,
better results.
Cardiokinase® works synergistically with these practitioner-curated cardiovascular additions.
Complete Your Protocol
Better together, better results.
HTNK-J® · Blood Flow · Heart Health
Cardiokinase®
Start here. 2,500 FU of HTNK-J® Nattokinase — the only strain endorsed by its discoverer, Dr. Hiroyuki Sumi. This is the fibrinolytic foundation every other layer of a cardiovascular protocol builds on.*
VESIsorb® Enhanced Absorption
Premium Omega-3 Plus
Omega-3s manage blood lipids and support endothelial function — the lipid layer that protects the circulatory work nattokinase does every day.*
Cellular Energy · Heart Support
Bioactive Coenzyme Q10
CoQ10 fuels the cardiac muscle cells that do the pumping — the energy layer that keeps the heart strong enough to benefit from improved blood flow.*
Deep Recovery Formula
Magnesium Glycinate
Magnesium supports healthy vascular tone and blood pressure already within the normal range — the relaxation layer that lets the whole system work efficiently.*
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