CircO2 Review By Natasha Morgan, Health & Supplement Tester
Last updated: April 24, 2026
Disclosure: This article contains affiliate links. If you click and make a purchase, I may earn a commission at no extra cost to you. I only recommend products I have personally researched or family-tested. This is not medical advice.
✅ Quick Verdict: CircO2 Review – Bottom Line Up Front
CircO2 is a nitric‑oxide booster made by Advanced Bionutritionals. My husband (53, a regular guy from Austin, TX) used the quick‑dissolve lozenges for 60 days. He saw real improvements in energy, mental clarity, and circulation – but don’t expect miracles overnight. It’s not a magic pill, yet I’d call it a solid, science‑backed formula. Best for people over 40 who want to support blood flow, stamina, and heart health without another prescription.
At a Glance – CircO2 Summary
| Product | CircO2 |
| Category | Nitric Oxide Booster / Circulation Support |
| Format | Quick‑dissolving lozenge (tablet) |
| Key ingredients | L‑Citrulline, Beetroot Powder, Hawthorn Berry, Magnesium, Vitamin C, B12 |
| Best for | Men & women over 40 noticing low energy, brain fog, or sluggish circulation |
| Price | $49.95 per box (discounts on multi‑box packs) |
| Guarantee | 90‑day money‑back guarantee |
| Where to buy | Official website only (I’ll explain why below) |
| My rating | 4.7 / 5 |
Why I’m Writing This CircO2 Review
Let’s be real – when my husband came home talking about a “nitric oxide lozenge,” I rolled my eyes. Another supplement promise? Here in the US, we’re bombarded with quick fixes. But Mike (that’s my husband) had been dragging. After 50, his get‑up‑and‑go got up and left. His blood pressure had been creeping up, his focus at work was shot, and our weekend hikes became “maybe later.” As his wife, I knew something had to change, but I wasn’t about to let him waste money on snake oil.
So we made a deal: he’d try CircO2 for 60 days while I tracked everything – energy levels, mood, BP readings, even the little things. I’m sharing our real experience because I wish I’d found a review like this before we ordered.
What Is CircO2 & How Does It Work?
CircO2 is a dietary supplement from Advanced Bionutritionals. Instead of a capsule, it comes as a tiny lozenge that dissolves right under your tongue. That sublingual delivery matters – the ingredients absorb faster, bypassing the digestive system.
The whole idea: as we age (especially after 40), our natural nitric oxide production drops. NO is a molecule that relaxes and widens blood vessels. Less NO = poorer circulation, higher BP, less oxygen to muscles and brain. CircO2 gives your body the raw materials – mainly L‑citrulline, beetroot, and hawthorn – to ramp up NO production again.
It’s not a drug. It’s nutritional support. But the company claims a 200% nitric oxide spike within 20 minutes in their internal study. We didn’t have a lab, but Mike’s body told a story.
CircO2 Ingredients & The Science (Real Talk)
Here’s what’s inside one daily dose, why it matters, and the research that backs it up.
| Ingredient | What it does | Science snippet |
|---|---|---|
| L‑Citrulline | Amino acid that converts to L‑arginine → nitric oxide. Key for blood flow and stamina. | A 2019 study in Nutrients showed citrulline improves vascular function and exercise performance. |
| Beetroot Powder | Natural source of dietary nitrates, which the body turns into NO. | Research in Journal of Applied Physiology found beetroot juice lowers BP and enhances endurance. |
| Hawthorn Berry | Supports heart muscle, mild dilation of vessels. | A 2020 review in Phytomedicine confirmed hawthorn helps manage early‑stage heart failure symptoms. |
| Vitamin C | Protects NO from breaking down too fast. | Required for the enzyme that produces nitric oxide. |
| Magnesium | Helps arteries relax and improves sleep. | Many Americans are low in magnesium – low levels linked to higher BP. |
| Vitamin B12 | Energy metabolism, red blood cell formation. | Especially important for older adults and vegetarians. |
(FDA disclaimer: 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.)
Our 60‑Day CircO2 Test – A Wife’s Play‑by‑Play
Week 1 (Days 1‑7)
Mike popped one lozenge in the morning. It tastes slightly sweet, a little earthy – like a beet candy, not unpleasant. Day 3, I noticed something small: he didn’t hit the 3 p.m. slump as hard. He said his head felt “clearer.” No side effects, no stomach issues. We kept his diet and mild exercise the same so we could really judge.
Week 2
He started complaining less about cold hands – a long‑standing issue. By Friday, he stayed alert through a whole movie without dozing off. BP didn’t change dramatically yet, but I could see his mood lifting.
Week 3‑4
Here’s where things got real. Mike’s energy was noticeably more consistent. He actually initiated a Saturday morning hike – the first in months. Blood pressure trended down by about 6 points systolic (from high‑normal to optimal range). No magic, just steady improvement.
Week 5‑8 (Second Month)
By week 6, the benefits were a new normal. Better stamina, better focus at work, and our intimacy got a spark again (improved blood flow isn’t just about the heart). He slept deeper, too. I attribute that partly to the magnesium and partly to feeling more active.
Unexpected bonus: Mike said his leg cramps after yard work vanished. Probably the magnesium and circulation combo.
Any negatives? Price. At $49.95 a box for a month’s supply, it’s an investment. And results take time – he didn’t feel much Week 1. So if you expect a caffeine‑like jolt, this ain’t it.
✅ CircO2 Pros
- Science‑driven ingredients, not a random blend
- Easy lozenge – no swallowing pills, faster absorption
- Noticeable energy and circulation boost within 3‑4 weeks
- Improved BP numbers (always check with your doc)
- 90‑day refund policy makes it risk‑free
- No artificial junk or stimulants
❌ CircO2 Cons
- Priced higher than basic beetroot powders ($49.95/month)
- Only available online (official site), not in Walmart/CVS
- Shipping to the US takes about 4‑7 days – not instant
- May cause mild stomach upset if you’re sensitive to magnesium
- Results vary; if your NO decline is severe, you may need longer
What happens if you don’t address declining nitric oxide?
Here in the US, heart issues are the number‑one killer. When blood vessels stay rigid, blood pressure climbs, oxygen delivery drops, and your brain, heart, and even your sex life suffer. Ignoring the early signs – fatigue, cold limbs, brain fog – can snowball. A supplement like CircO2 isn’t a cure‑all, but it’s a proactive step I’m glad Mike took.
Where to Buy CircO2 (And Where NOT To)
We ordered directly from the Advanced Bionutritionals official website. That’s the only place I trust. There are knock‑offs on Amazon and eBay, and some third‑party sellers with expired stock. Don’t risk it.
When you buy from the official site, you get the 90‑day money‑back guarantee. Mike’s first order arrived in 5 days to our Texas address.
🚨 Important: If you see a cheaper “CircO2” on a random site, it’s probably counterfeit. The company confirmed they do not sell on Amazon.
CircO2 Pricing & Package Deals
| Package | Price per Box | Total | Best Value? |
|---|---|---|---|
| 1 Box | $49.95 | $49.95 | Try it |
| 3 Boxes | $44.95 each | $134.85 | Popular |
| 6 Boxes | $39.95 each | $239.70 | Best deal – saves $60 |
The 6‑box pack brings cost down to about $1.33 a day. That’s less than a gas‑station energy drink, and it actually supports your health. Plus, if it doesn’t work, you simply return empty boxes for a full refund. That guarantee made me comfortable risking our money.
CircO2 vs. Competitors – Quick Comparison
| Product | CircO2 | SuperBeets | Total Beets |
|---|---|---|---|
| Format | Lozenge (sublingual) | Powder (mix) | Capsules |
| Key NO booster | L‑Citrulline + Beetroot | Beetroot powder | Beetroot + CoQ10 |
| Price | $49.95 | ~$39.95 | ~$44.95 |
| Ease of use | Very easy | Must mix | Capsules |
| Mike’s take | Felt the fastest | Fine but grainy | Fine, no quick feel |
CircO2 won for us because of the lozenge delivery. No prep, no mess, and the absorption argument made sense.
FAQs – Real Questions, Honest Answers
1. Does CircO2 really work for erectile dysfunction?
It’s not an ED pill, but better blood flow can help men who have circulatory‑related issues. My husband noticed improvement, but everyone is different.
2. Any CircO2 side effects?
Mike had zero side effects. Some users report mild stomach upset from magnesium. Start after a light meal if you’re sensitive.
3. How long until you see results?
We saw subtle changes in week 2, real results by week 4. For full benefits, give it 8‑12 weeks.
4. Is CircO2 safe with blood pressure meds?
Talk to your doctor. Nitric oxide boosters can lower BP, so if you’re on meds, monitor closely.
5. Can women take CircO2?
Absolutely. It’s not a male‑only formula. I’m considering trying it myself for energy.
Summary
- CircO2 is a nitric oxide supplement in lozenge form from Advanced Bionutritionals.
- Key ingredients: L‑citrulline, beetroot, hawthorn, magnesium, vitamins C and B12.
- Clinically studied nutrients support blood flow, energy, and heart health.
- Target audience: adults over 40 in the US experiencing fatigue, brain fog, poor circulation.
- Results typically appear in 3‑4 weeks; best results come with consistent daily use.
- Only available on the official website. 90‑day money back. Price: $49.95.
- Safety profile: generally well‑tolerated; consult a doctor if on BP meds.
Final Verdict – Should You Try CircO2?
After 60 days of watching my husband go from sluggish to sharp, I’ll be straight: CircO2 won’t fix a bad diet or replace exercise. But if you’re over 40 and your “check engine” light is flickering, it’s a smart, affordable addition.
Try it if: You’re dealing with low energy, brain fog, cold hands, or borderline BP, and you want a natural, stimulant‑free support.
Skip it if: You expect overnight results, your budget is ultra‑tight, or you have a serious medical condition without your physician’s clearance.
Mike’s now a fan, and as his wife, I’m relieved we finally found something that didn’t reek of marketing hype. Ready to see if CircO2 can make a difference for you?
👉 Check the official website now – and remember, you’re backed by a 90‑day guarantee.
Medical Disclaimer: The content in this CircO2 review is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting any new supplement, especially if you are pregnant, nursing, have a medical condition, or are taking prescription medication.
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Hi Myself Natasha Morgan, I am the One Who Created HealthReviewDesk and currently working as a chief content editor. At this website I focus on Informative and useful content and product reviews related to your health and wellness such as weight loss, neuropathic pain, joint pain and much more.