1 13

"Whether I'm running, hiking, or lifting, it keeps me going without any crashes. Easy to take and no aftertaste."

Anna Bilyk

Atlanta, GA

"My muscle recovery is way better. Usually I'd be sore for days after leg day, but now I feel ready to go the next morning."

Naeem Mahmood

Seattle, WA

"The first thing I noticed was my energy level - more awake, focused, and motivated throughout the day."

Ana Paula Lima Silva

Dallas, TX

"Recovery feels quicker, which is a huge win because it helps me stay consistent without burning out."

Brian Pray

Chicago, IL

"My energy feels steady from start to finish, even on my toughest gym days. Recovery is where this product shines."

Haniel Velez Rosario

Miami, FL

Formulation Factory

Heart of Steel

Name: Heart of Steel
Brand: Formulation Factory
SKU: HEART-OF-STEEL-01
Price: 59.99 USD
Availability: InStock
Rating: 4.7 (782 reviews)

4.7 ★★★★★ (782)

~~$59.99~~ One-time purchase

-20%$48⁰⁰

10 ingredients across 3 bloodflow pillars - pumps blood, opens vessels, strengthens cardiovascular health
Real doses. No proprietary blends. - Every ingredient and dose printed on the label.
Made in USA. Formulated in 2026. - Don't fall for a stale formula. #NeverStopImproving
100-day money-back guarantee - Don't feel it? Keep the bottle. Full refund, no questions.

Subscription auto-renews at $48.00 every 2 months until cancelled. Cancel anytime at formulationfactory.com/a/account/login.

Heart of Steel

The three-pillar approach to bloodflow optimization.

Most cardiovascular supplements stop at one ingredient and call it a day. Heart of Steel doesn't. Because real circulation isn't one thing - it's a system. The body needs to make nitric oxide, keep vessels open, and protect the cells lining them. Miss a step and the rest underperform.

We built Heart of Steel to address all three.

Pillar 1 - Nitric Oxide Production

Nitric oxide is the molecule your blood vessels use to dilate. More NO means better circulation, better pumps, and lower vascular resistance. Two ingredients in Heart of Steel target this pathway directly:

L-Citrulline - 1,000 mg - the most bioavailable precursor to L-Arginine and a clinically studied driver of NO production
L-Arginine HCl - 400 mg - the direct substrate for nitric oxide synthase

Full doses of each. Listed on the label.

Pillar 2 - Vasodilation & Circulation

Producing NO is one half of the equation. Keeping vessels open and blood moving is the other. These ingredients support healthy blood flow, vasodilation, and microcirculation:

Ginkgo Biloba - 200 mg of 10:1 extract - studied for its role in peripheral and cerebral circulation
Coleus Forskohlii - 100 mg of 10% forskolin extract - traditionally used to support vascular tone
Capsaicin - 20 mg of 1% extract - supports peripheral blood flow and thermogenesis

Pillar 3 - Cardiovascular Protection

Blood vessels are constantly under oxidative stress. Antioxidants protect endothelial cells and support long-term cardiovascular function. The most overlooked pillar in most cardio formulas:

CoQ10 (Ubiquinone) - 200 mg of 99% pure - a foundational antioxidant for mitochondrial and cardiovascular health
Resveratrol - 200 mg of 98% extract - studied for endothelial support and antioxidant capacity
Quercetin Dihydrate - 200 mg of 95% extract - a flavonoid associated with cardiovascular and circulatory support

What's not in it

No proprietary blends. Every dose is on the label.
No unnecessary fillers. No artificial colors.
No fairy dust. Real doses of every ingredient.

What's behind it

Manufactured in an FDA-registered, GMP-certified facility
Every lot third-party tested
Full label disclosure on the bottle and the website

Who it's for

Heart of Steel is built for people who already train, already eat well, and want a research-backed formula that supports the cardiovascular system at every level. If you're looking for a stim-loaded pre-workout, this isn't it. If you want a foundational daily formula built on how circulation actually works, you're in the right place.

Supplement Facts

Serving Size: 4 Capsules

Servings Per Container: 30 servings

Amount Per Serving % Daily Value

L-Citrulline 1000 mg †

L-Arginine 400 mg †

CoQ10 200 mg †

Resveratrol 200 mg †

Ginkgo Biloba 200 mg †

Quercetin Dihydrate 200 mg †

Panax Ginseng 100 mg †

Rhodiola Rosea 100 mg †

Coleus Forskohlii 100 mg †

Capsicum Annuum 20 mg †

† Daily Value not established.

Other Ingredients: See product label for full other ingredient information.

Take 4 capsules in the morning with food. L-Citrulline and CoQ10 absorb best with a meal, and morning dosing supports blood flow and cardiovascular function throughout your active hours.

Take daily and consistently. Cardiovascular and metabolic benefits compound over time. Most users report improved endurance and workout recovery within 2-3 weeks.

WARNING: Risk of cancer and reproductive harm from exposure to lead. See www.P65Warnings.ca.gov/food

Results build with consistent usage over time.

Consult a qualified healthcare professional before use if you are pregnant, nursing, taking medication, or have an existing medical condition. Discontinue use and seek medical advice if any adverse reaction occurs.

Not intended for persons under 18. Keep out of reach of children. Store in a cool, dry place away from direct sunlight.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Individual results may vary. Content on this page is for informational purposes only and is not a substitute for professional medical advice.

L-Citrulline 1000 mg
An amino acid your body converts into L-arginine and then into nitric oxide. Researched for supporting healthy blood flow, endurance, and circulation during physical effort.
L-Arginine 400 mg
An amino acid that serves as the body's direct precursor to nitric oxide. Supports vascular flexibility, healthy circulation, and natural blood flow.
CoQ10 200 mg
A coenzyme produced naturally in cells, with levels typically declining with age. Supports cellular energy production, heart muscle function, and recovery from physical stress.
Resveratrol 200 mg
A polyphenol concentrated in Japanese knotweed and red wine grapes, standardized for trans-resveratrol. Traditionally used to support cardiovascular health, healthy aging, and circulation.
Ginkgo Biloba 200 mg
A leaf extract from one of the oldest tree species on earth, standardized for flavone glycosides and terpene lactones. Traditionally used to support cognitive sharpness, healthy circulation, and mental clarity.
Quercetin Dihydrate 200 mg
A bioflavonoid found naturally in onions, capers, and apples. Supports a healthy inflammatory response, capillary integrity, and immune function.
Panax Ginseng 100 mg
A revered Asian root with thousands of years of traditional use, standardized for ginsenosides. Traditionally used to support natural energy, mental clarity, and stamina.
Rhodiola Rosea 100 mg
An adaptogenic root from the cold mountain regions of Europe and Asia, standardized for rosavins and salidroside. Traditionally used to support stress resilience, endurance, and physical recovery.
Coleus Forskohlii 100 mg
A root from the Indian mint family, standardized for forskolin. Researched for supporting cardiovascular function, healthy metabolism, and lean body composition.
Capsicum Annuum 20 mg
A chili pepper extract, standardized for capsaicinoids. Supports thermogenesis, healthy circulation, and metabolic activity.

The Real Cost of Health

One Bottle Replaces 10 Supplements.

See what you're actually spending - and what you could keep.

Ingredient

Dose

Buying separate

10 individual products - per month

Various brands

Included

Buying separately - 10 separate supplements

Heart of Steel - Subscribe & Save

You save - / month

Individual supplement prices reflect the median one-time retail price for a 30-day supply of comparable single-ingredient capsules sold on Amazon. Prices were researched at time of publication, may vary, and are provided for estimation purposes only. Subscribe & Save pricing reflects a 20% discount off list price. Cancel anytime.

Meet our medical advisor

Dr. Oliver Zolman, MBBS BSc
Medical Advisor to Formulation Factory

Dr. Oliver Zolman, MBBS BSc, serves as Medical Advisor to Formulation Factory. A King's College London-trained medical doctor working in evidence-based longevity medicine, Dr. Zolman is known for advancing structured, biomarker-driven protocols that integrate lifestyle, clinical, and emerging therapies into systematic frameworks for human healthspan.

He co-founded Project Blueprint with Bryan Johnson, developing biological age measurement protocols across 82 organ types, and his work has been featured in Bloomberg, The Times, and Esquire.

Every Formulation Factory product carrying his endorsement has been reviewed and signed off against his evidence-based standard.

HEART OF STEEL is made for anyone who needs more out of their body and brain — whether you're lifting heavy, grinding through long workdays, or just want to feel more alive in your skin. It's built for both men and women who want better endurance, faster recovery, cleaner energy, and serious support for heart and metabolic health.
Most users notice better blood flow, stamina, and energy within the first 1–2 weeks. Over time, you’ll feel more consistent endurance during workouts, quicker recovery, and less midday crash. Because it’s stimulant-free, the effects are steady—not spiked—so think performance that builds, not burns out.
Ingredients like L-Citrulline and L-Arginine ramp up nitric oxide levels, improving blood flow and oxygen delivery to muscles. Rhodiola and Ginseng help fight fatigue and mental burnout. The result? More reps, more focus, and more grind — without needing a pre-workout every time.
CoQ10, Resveratrol, Quercetin, and Ginkgo all support vascular function, heart health, and antioxidant defense. That means smoother circulation, lower inflammation, and better recovery after tough sessions. You’re not just building muscle — you’re building resilience.
Yes. HEART OF STEEL uses clean, natural ingredients that are safe for daily use and stack well with most fitness or wellness supplements. No hormones, no weird side effects. It’s designed for consistent, long-term results. As always, if you’re taking meds or have a condition, check in with your doctor.

Keep It 100. Not feeling it? Keep Your Money and the Bottle.

Don't feel the difference in 100 days? Keep the bottle. We refund every cent. Full money-back guarantee — no returns, no forms, no runaround.

42%

MACE Reduction

CoQ10

Dose: 300mg / day
Duration: 2 years
Subjects: 420 heart failure patients

4.5mmHg

Blood Pressure

L-Citrulline

Dose: 3–11g / day
Duration: 1–16 weeks
Subjects: Adults across 14 RCT arms

12μmol/L

Nitric Oxide

L-Arginine

Dose: Varied by trial
Duration: Varied
Subjects: 323 CVD/metabolic patients

Studies cited reference individual actives in this formula at the doses tested. Results from individual ingredient studies may not reflect the full formula. Individual results may vary.

4.7

Rated 4.7 out of 5 stars

Based on 782 reviews

Total 5 star reviews: 664 Total 4 star reviews: 68 Total 3 star reviews: 18 Total 2 star reviews: 1 Total 1 star reviews: 31

94%would recommend this product

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782 reviews

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K
Karen
Rated 3 out of 5 stars
Yesterday
3 Stars
I dont notice a huge difference in how I feel.
I’m on my third bottle, taking it to protect my heart.
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D
Dustin
Verified Buyer
I recommend this product
Rated 5 out of 5 stars
2 weeks ago
Works great
Works great I use them before workouts
Was this helpful?
GM
Gene M.
Verified Buyer
I recommend this product
Rated 5 out of 5 stars
1 month ago
Excellent product
This is my second purchase, and it's made me feel much better with the BP issues.
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GM
Gregory M.
Verified Buyer
I recommend this product
Rated 5 out of 5 stars
1 month ago
Its ok
So far so good
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GM
Gregory M.
Verified Buyer
I recommend this product
Rated 5 out of 5 stars
1 month ago
Its ok
So far so good
Was this helpful?

Reviews reflect the individual experiences of verified customers. Specific results described - including hormone levels, biomarker changes, energy, focus, or physical changes - are not typical and are not guaranteed. Individual results vary based on age, baseline health, diet, sleep, training, stress, and other factors. Formulation Factory does not independently verify customer-reported outcomes. These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.

Our Promise

Keep It 100. Risk-Free.

Don't feel it? Keep the bottle. Full refund.

Heart of Steel

Heart of Steel

Pillar 1 - Nitric Oxide Production

Pillar 2 - Vasodilation & Circulation

Pillar 3 - Cardiovascular Protection

What's not in it

What's behind it

Who it's for

What's Inside

L-Citrulline 1000 mg

L-Arginine 400 mg

CoQ10 200 mg

Resveratrol 200 mg

Ginkgo Biloba 200 mg

Quercetin Dihydrate 200 mg

Panax Ginseng 100 mg

Rhodiola Rosea 100 mg

Coleus Forskohlii 100 mg

Capsicum Annuum 20 mg

One Bottle Replaces 10 Supplements.

Meet our medical advisor

Frequently Asked Questions

Keep It 100. Not feeling it? Keep Your Money and the Bottle.

Proof, not promises

CoQ10

L-Citrulline

L-Arginine

Keep It 100. Risk-Free.