CircO2™ is a quick-dissolve sublingual lozenge from Advanced Bionutritionals — place one on your tongue daily and let it dissolve. Formulated with L-Citrulline, Beet Root Powder, and Hawthorn Berry Extract to support your body's natural nitric oxide production, healthy circulation, and steady energy.
Most nitric oxide supplements get swallowed and processed through your digestive system. CircO2 works differently — one quick-dissolve lozenge on the tongue daily, allowing the active ingredients to interact directly with oral tissue for faster, more efficient absorption.
In 1998, three scientists won the Nobel Prize in Physiology or Medicine for discovering how nitric oxide — a tiny gas molecule produced naturally in the body — controls and coordinates the cardiovascular system. Since then, research has consistently confirmed its role in relaxing blood vessels, supporting healthy circulation, and maintaining efficient oxygen delivery to every cell, tissue, and organ.
Beginning in your 40s and accelerating through each decade, the body's ability to produce nitric oxide naturally diminishes. Endothelial cells — the lining of your blood vessels — become less efficient, and the precursor compounds that fuel nitric oxide synthesis become harder to maintain at adequate levels.
When nitric oxide levels drop, blood vessels lose some of their flexibility. Circulation becomes less efficient. Oxygen delivery to muscles, the brain, and vital organs slows. The result is something most people experience as a gradual reduction in energy, stamina, and physical resilience rather than a single dramatic event.
Nitric oxide production begins in the mouth — oral bacteria play a direct role in converting dietary nitrates into nitric oxide. A lozenge that dissolves under the tongue maximizes this pathway, allowing active ingredients to interact directly with saliva and oral tissue rather than passing through the digestive system first.
CircO2 was formulated specifically around these mechanisms — starting with sublingual delivery and building outward from there.
💧 ORDER NOWCircO2 is a quick-dissolve sublingual lozenge developed by Advanced Bionutritionals and formulated with six active ingredients — L-Citrulline, Beet Root Powder, Hawthorn Berry Extract, Vitamin C, Vitamin B12, and Sodium Nitrite — designed to support the body's natural nitric oxide production, healthy circulation, energy levels, and cardiovascular wellness.
What makes it distinct is the delivery format: rather than being swallowed and digested, each lozenge dissolves on or under the tongue, activating with saliva to engage the oral-to-nitric oxide conversion pathway more directly. One lozenge daily — no water required, no capsule to swallow.
It is vegan, non-GMO, gluten-free, and free from preservatives, soy, dairy, eggs, and nuts. Manufactured in the United States at a GMP-certified, FDA-registered facility by Advanced Bionutritionals. Backed by a 90-day money-back guarantee.
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Each of the six ingredients in CircO2 supports nitric oxide production or protects it from breaking down too quickly — two distinct but complementary roles that make the formula work as a system rather than a collection of individual supplements.
An amino acid the body converts into L-arginine, which in turn supports nitric oxide synthesis. As a precursor, it supplies the raw material the endothelium needs to produce nitric oxide more efficiently.
Rich in inorganic nitrates, beet root provides a direct dietary source that oral bacteria convert to nitrate, then nitrite, and ultimately nitric oxide — the other major production pathway alongside the L-citrulline route.
Traditionally used for centuries to support heart and circulatory health, Hawthorn Berry is rich in flavonoids and antioxidants that support healthy blood vessel tone and overall cardiovascular function.
A powerful antioxidant that protects nitric oxide molecules from oxidative degradation — essentially extending the effective lifespan of the nitric oxide your body produces, so it can continue supporting circulation longer.
Supports healthy red blood cell formation and energy metabolism — contributing to the formula's energy and stamina benefits through the cellular oxygen-delivery pathway alongside nitric oxide's vascular effects.
Provides a direct source of nitrite that the body can convert to bioavailable nitric oxide — complementing the indirect L-citrulline and beet root pathways with a more immediate nitric oxide contribution.
Sandra B., 68
★★★★★ ✔ Verified Purchase"The sublingual delivery is what makes this different from other supplements I've tried. Something you dissolve on your tongue just feels like it works faster. Two months in and my afternoon energy is noticeably steadier and my morning walks feel less of an effort than they used to."
Thomas W., 74
★★★★★ ✔ Verified Purchase"I'd read about nitric oxide and its role in circulation before trying this. The fact that it uses beet root and L-citrulline together — two well-documented precursors — rather than just one of them is what convinced me. Three months in now and my energy through the day is more consistent than it's been in years."
Linda K., 71
★★★★★ ✔ Verified Purchase"I asked my doctor before starting, showed her the full ingredient list, and she had no concerns. Four months on the 6-box plan now. The format is so easy — one little lozenge in the morning that's dissolved before I've finished making coffee. The energy and mental clarity difference has been genuinely noticeable."
Natural nitric oxide support builds progressively — most people notice initial changes within the first week, with more significant improvements typically appearing by month two or three. The 90-day guarantee is designed specifically to give the formula enough time to demonstrate what it can do.
If you're unsatisfied for any reason within 90 days of purchase, return the product for a full refund. No complicated process, no questions asked.
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CircO2 is a quick-dissolve sublingual lozenge from Advanced Bionutritionals formulated with L-Citrulline, Beet Root Powder, Hawthorn Berry Extract, Vitamin C, Vitamin B12, and Sodium Nitrite to support the body's natural nitric oxide production, healthy circulation, and sustained energy.
Place one lozenge on or under the tongue and allow it to dissolve fully — do not chew or swallow whole. Avoid eating or drinking for at least 5 minutes after. One lozenge daily, ideally on an empty stomach in the morning.
Capsules must be swallowed and digested before their ingredients can be absorbed. CircO2's sublingual format dissolves on the tongue, where saliva activates the ingredients and the oral tissue allows more direct absorption — bypassing the digestive process and engaging the oral nitrate-to-nitric oxide conversion pathway more effectively.
CircO2 contains L-Citrulline, Beet Root Powder, Hawthorn Berry Extract, Vitamin C, Vitamin B12, and Sodium Nitrite. These six ingredients work together across two complementary nitric oxide production pathways, with Vitamin C also acting to protect nitric oxide from breaking down too quickly.
CircO2 starts at $49.95 per box and decreases with 3 and 6-box bundles, with the best per-box price from $41.50 on the 6-box bundle. Every purchase is protected by a 90-day, 100% satisfaction money-back guarantee. Rated 4.9/5 across 79,840+ verified reviews.
The only daily lozenge that dissolves on your tongue to support nitric oxide from two complementary pathways — L-citrulline and beet root — backed by 90 risk-free days to experience the difference.