Edited by Michael Anderson, Editor-in-Chief
Updated
CircO2 Nitric Oxide Booster: Ingredient List and How They Combine
Every ingredient in CircO2 Nitric Oxide Booster, with the dose where disclosed and what it actually does — in plain English. Honest acknowledgment of the proprietary blend trade-off, plus how the four NO ingredients work together.
4 active NO ingredients + 3 cofactors in a single daily lozenge.
In This Article
What's Inside
Nothing in CircO2 is there by accident. Four ingredients form the Nitric Oxide Blend (420 mg total): Beet root powder — same compound Olympic athletes use for stamina. Hawthorn berry — centuries of traditional heart support. L-citrulline — the NO precursor that actually works after 45 (L-arginine doesn't). Sodium nitrite — direct NO substrate. Wrapped around them: Vitamin B12 (1,000 mcg) for the deficiency 30% of adults over 50 already have, Vitamin C (100 mg) as both catalyst and protector, and trace Magnesium. The honest trade-off: individual doses inside the Proprietary Blend aren't disclosed — but the four ingredients are independently validated, and clinical testing shows the whole thing delivers a 200% NO boost in 20 minutes via the lozenge.
THE CORE PROMISE
Every ingredient in this lozenge exists for one job — restoring the nitric oxide your body used to make plenty of, and stopped. Most "nitric oxide" supplements lose 75% of their potency to digestion — and stop working after age 45. The CircO2 lozenge skips that entirely: it activates NO production in your mouth, the way MIT scientists discovered the process actually starts. Result: a 200% NO boost in 20 minutes — daily, with one lozenge under the tongue. That's the whole promise.
1. Inside the 4-Ingredient Nitric Oxide Blend
The first thing you’ll notice when you read the CircO2 supplement facts: there are very few ingredients. That’s by design. The formula concentrates on one job — restoring nitric oxide — and uses four core ingredients in a Proprietary Blend to do it, plus three cofactors (B12, Vitamin C, Magnesium) that amplify the production chain. The trade-off worth knowing up front: the 4 ingredients inside the 420 mg Proprietary Nitric Oxide Blend are listed by name but not by individual dose. The mechanism still works (each is independently validated for NO support), but ingredient-level dose verification isn’t possible.
2. Full Ingredient Table
| Ingredient | Dose | Role |
|---|---|---|
| Vitamin B12 (methylcobalamin) | 1,000 mcg (41,667% DV) | Addresses the B12 deficiency 30% of adults over 50 already have. Amplifies energy and nitric oxide production capacity at the same time. The "methylcobalamin" form is the bioactive version — your body uses it directly without conversion. |
| Vitamin C (magnesium ascorbate + ascorbic acid) | 100 mg (111% DV) | Acts as a catalyst for nitric oxide production AND as an antioxidant guardian, protecting NO from oxidative damage once it's made. The blended form (magnesium ascorbate) also doubles as the carrier for the trace magnesium. |
| Magnesium (from magnesium ascorbate) | 4 mg (1% DV) | Trace dose — acts as the Vitamin C carrier, not as a therapeutic magnesium intervention. If magnesium is your priority, supplement it separately with a dedicated product. |
| Proprietary Nitric Oxide Blend | 420 mg total | The hero blend. Contains four ingredients (below) — individual doses not disclosed. |
| ↳ Beet Root Powder (in Blend) | part of 420 mg | Rich in natural dietary nitrates. The same compound Olympic athletes use beet juice for. Oral bacteria convert these nitrates into nitric oxide via the MIT-discovered mouth pathway. |
| ↳ Hawthorn Berry Extract (in Blend) | part of 420 mg | Centuries of traditional use for heart and circulation support. Modern research: enhances how efficiently the body absorbs and uses nitric oxide. Means more usable NO per dose. |
| ↳ L-Citrulline (in Blend) | part of 420 mg | Converts to nitric oxide more effectively than L-arginine — and works even after age 45, when the L-arginine pathway weakens. Bypasses the 75% digestive loss problem of L-arginine. |
| ↳ Sodium Nitrite (in Blend) | part of 420 mg | Direct nitric oxide substrate. Provides NO precursor that doesn't depend on multi-step digestive conversion — a fast, reliable source. |
3. How They Work Together
Here’s the simple way to think about it: CircO2 does two things in parallel — it delivers pre-formed nitrate substrates for fast NO production via the oral pathway, and it supports the body’s NO production machinery through Vitamin B12, Vitamin C, and L-citrulline.
Pathway 1 — Mouth bacteria activation (Beet root + Sodium nitrite). When the lozenge dissolves on the tongue, oral bacteria convert dietary nitrates into nitrites, which then become nitric oxide. This is the MIT discovery — and the reason CircO2 outperforms standard L-arginine pills. The 200% NO boost in 20 minutes happens through this pathway.
Pathway 2 — Cellular NO production support (L-Citrulline). Inside cells, L-citrulline converts to L-arginine, which then becomes nitric oxide. This bypasses the digestive losses that handicap standard L-arginine pills. Works particularly well after age 45 when the standard L-arginine pathway weakens.
Pathway 3 — Absorption enhancement (Hawthorn berry). Increases how efficiently the body uses the NO it produces — more usable nitric oxide per dose of the other ingredients.
Pathway 4 — Cofactor amplification (B12 + Vitamin C). B12 supports overall NO production capacity. Vitamin C catalyzes new NO formation AND protects existing NO from oxidative damage. Together they multiply the effective output of the other ingredients.
4. What Makes This Formula Different
Three things separate CircO2 Nitric Oxide Booster from the average nitric oxide supplement:
Lozenge delivery via the MIT-discovered oral pathway. Most NO supplements use capsules that go to the gut — losing 75% to digestion. The lozenge format triggers the mouth-bacteria conversion that MIT identified as critical, delivering 200% NO boost in 20 minutes (measured in clinical testing).
L-citrulline instead of L-arginine. The traditional NO precursor (L-arginine) becomes ineffective after age 45 because the conversion pathway weakens. L-citrulline gets absorbed first and converts to L-arginine inside the cell — bypassing the digestive loss entirely.
Real B12 dose at 1,000 mcg. Many NO supplements skip B12 or include trace amounts. CircO2 includes a clinically meaningful 1,000 mcg of methylcobalamin — addressing the deficiency 30% of adults over 50 already have and amplifying NO production capacity. The trade-off, as noted, is the proprietary blend hides the individual NO ingredient doses. For products with full dose disclosure across a different mechanism (cellular/mitochondrial energy), see Advanced Mitochondrial Formula from the same manufacturer.
Pricing Options for CircO2 Nitric Oxide Booster
CircO2 is available in three bundle options. Most users choose the 6-box bundle because the daily lozenge habit builds cumulative effect — and the per-day cost drops to $1.38. The "Biggest Savings" 6-box bundle locks in $41.50 per box, includes free shipping, and saves $50.70 vs single-box pricing.
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Shop NowEvery order is backed by a 90-day money-back (Down to the Last Lozenge). Only available through the official website.
Frequently Asked Questions
Why is there a proprietary blend?
The 420 mg Nitric Oxide Blend lists all four ingredients (beet root, hawthorn berry, L-citrulline, sodium nitrite) but not the individual doses for each. Manufacturers sometimes use this format to protect formulation specifics from competitors. The downside for buyers is that you can't verify clinical-relevant doses for any single ingredient — but each of the four is independently validated for NO production, and clinical testing on the finished product demonstrates the 200% NO boost in 20 minutes.
Why L-citrulline instead of L-arginine?
L-arginine loses up to 75% of its potency during digestion, and after age 45 the body's ability to convert it to NO weakens significantly. L-citrulline is absorbed intact, then converts to L-arginine inside the cell — bypassing both the digestive loss and the age-related conversion problem. It's the better NO precursor for adults over 45.
Should I stack this with a B12 supplement?
Probably not — CircO2 already contains 1,000 mcg of methylcobalamin (41,667% of the Daily Value), which is a clinically meaningful B12 dose. Stacking another B12 product on top wouldn't provide additional benefit for most users (B12 is water-soluble; excess is excreted). If you have a diagnosed B12 deficiency, your doctor should guide dosing.
Continue your research
- Next: Does it actually work? — week-by-week timeline + mechanism
- Then: Side effects + safety — interactions, who should consult a doctor
- Compare: Nitric Boost Ultra — dual-pathway capsule alternative with full dose disclosure
- Best deal: Pricing breakdown — 6-box bundle math
Research & Transparency
This content is based on publicly available ingredient research, manufacturer disclosures, and product labeling. We are not affiliated with the manufacturer.
(a) Nitric oxide and aging — declining endothelial production. PMC3168675
(b) Dietary nitrates and oral bacteria — the entero-salivary nitrate-nitrite-nitric oxide pathway. PMC2731686
(c) L-citrulline vs L-arginine supplementation for nitric oxide and vascular function. PMC5598028
(d) Beetroot juice supplementation, blood pressure, and exercise performance. PMC5409708
About the Author
James Mitchell is a contributor at The Supplement Post focusing on men's health, circulation, and performance-support supplementation. He covers prostate and urinary flow support, nitric oxide for both vascular and athletic output, mitochondrial energy, and recovery formulas. He specializes in analyzing how ingredients align with cellular bioenergetics and practical buyer considerations — including how to judge a supplement fairly over a realistic timeline. James Mitchell is not a medical doctor. He analyzes publicly available research and regulatory guidance to provide evidence-aware, consumer-friendly summaries for adults exploring vitality, circulation, and performance support options.
Disclosure
All content is for informational purposes only and is not a substitute for professional medical advice. Each product reviewed is a dietary supplement, not a prescription drug. Results may vary based on individual health status, consistency of use, and lifestyle. This page may contain affiliate links — if you purchase through them, we may earn a small commission at no additional cost to you. Read our Editorial Policy.