CircO2 Review (2025): Is It Worth the Money?
Last Updated: November 2025
💰 Price: Starting at $49.95 per box
⏰ Results Timeline: 2-3 weeks for initial improvements, optimal benefits in 2-3 months
✅ Best For: Adults 40+ experiencing age-related circulation decline, fatigue, or seeking cardiovascular support.
❌ Not For: Individuals expecting immediate dramatic results, those on multiple medications without medical supervision, or people with severe cardiovascular disease requiring medical treatment.
🌟 CircO2
Naturally Boost Nitric Oxide for Enhanced Circulation & Energy
The Problem: The Silent Drain on Your Vitality
As we age, a subtle but significant shift occurs within our bodies: the natural production of nitric oxide (NO) begins to decline. This tiny molecule is a powerhouse, critical for maintaining healthy blood vessel flexibility, efficient oxygen flow, and robust energy production. By the time many individuals reach 40, their body’s nitric oxide production can be reduced by half, potentially leading to a cascade of unwelcome symptoms like persistent fatigue, cold hands and feet, brain fog, and a general decline in physical and mental stamina. This age-related decrease in NO isn’t just an inconvenience; it can impact overall cardiovascular health and diminish the vitality that makes life enjoyable.
What Is CircO2?
CircO2 is a dietary supplement developed by Advanced Bionutritionals, designed to naturally support the body’s production of nitric oxide. Unlike traditional oral supplements, CircO2 comes in the form of quick-dissolving lozenges that are placed under the tongue for potentially faster and more efficient absorption of its active compounds directly into the bloodstream.
The supplement aims to counteract the age-related decline in nitric oxide, which is essential for cardiovascular health, energy, and overall vitality. By enhancing nitric oxide levels, CircO2 helps relax and widen blood vessels, thereby improving circulation and ensuring that oxygen and nutrients are efficiently delivered to all organs and tissues. This can lead to various benefits, including increased energy, enhanced stamina, improved cognitive function, and better heart health. CircO2 is primarily marketed towards adults over 40 who are experiencing symptoms of age-related circulation decline or those looking to proactively support their cardiovascular wellness.
How It Works
CircO2 operates by leveraging a sophisticated nitric oxide enhancement system, targeting the body’s natural pathways for NO production. The core mechanism revolves around the conversion of L-citrulline and the utilization of dietary nitrates.
When a CircO2 lozenge dissolves under the tongue, L-citrulline is absorbed, bypassing initial liver metabolism. Once in the bloodstream, L-citrulline is converted to L-arginine, which then transforms into nitric oxide through the nitric oxide synthase enzyme pathway in the endothelium (the inner lining of blood vessels). This process triggers vasodilation, where blood vessels relax and widen, directly improving blood flow and oxygen delivery throughout the body.
In parallel, the beetroot powder in CircO2 provides a rich source of natural nitrates. These nitrates are converted to nitrites in saliva through bacterial reduction, and then further transformed into nitric oxide in the acidic environment of the stomach. This dual-pathway approach ensures consistent nitric oxide availability, supporting both immediate and long-term circulation improvements.
Additionally, ingredients like Hawthorn Berry extract support cardiovascular tissue by promoting healthy circulation and flexible blood vessels, while Vitamin C and B12 contribute to nitric oxide production and overall cellular function. This comprehensive mechanism works synergistically to enhance blood flow, oxygenation, and nutrient transport, addressing circulation at multiple physiological levels.
Key Ingredients / Features
| Ingredient/Feature | Details & Benefits |
|---|---|
| L-Citrulline | An amino acid that is a precursor to nitric oxide production, supporting healthy blood pressure and vascular function. It is more bioavailable than L-arginine for NO synthesis. |
| Beet Root Powder | Rich in natural nitrates that the body converts into nitric oxide, improving oxygen delivery to muscles and tissues, and enhancing blood flow. |
| Hawthorn Berry Extract | Supports heart health by promoting healthy circulation, flexible blood vessels, and may help strengthen cardiovascular tissue. |
| Vitamin C (as magnesium ascorbate and ascorbic acid) | A powerful antioxidant that stimulates enzymes critical for nitric oxide production and helps protect NO from oxidative degradation. |
| Vitamin B12 (as methylcobalamin and cyanocobalamin) | Essential for energy metabolism and cellular function, contributing to nitric oxide production in cells and supporting overall vitality. |
| Magnesium | A vital mineral involved in numerous biochemical reactions, supporting healthy blood circulation and overall cardiovascular function. |
| Sublingual Lozenges | Quick-dissolving tablets that allow for rapid absorption of active compounds directly into the bloodstream, bypassing digestive processing for potentially faster effects. |
| Natural Flavors, Xylitol, Stevia | Used for taste and as sweeteners, contributing to the "delicious berry flavor" reported by some users. |
Pros & Cons
What We Love (Pros)
- Clinically-Backed Ingredients: CircO2 contains ingredients like L-citrulline, beetroot powder, and hawthorn berry, all of which have been studied for their cardiovascular benefits and ability to support nitric oxide production.
- Convenient Lozenge Format: The sublingual lozenge delivery system allows for rapid absorption of active ingredients directly into the bloodstream, potentially leading to faster effects compared to traditional capsules or powders.
- Multi-System Benefits: Users frequently report a range of benefits beyond just circulation, including enhanced energy levels, improved stamina, better mental clarity, and even improved sleep quality.
- Third-Party Testing & Quality: Advanced Bionutritionals states that CircO2 is manufactured in an FDA-approved, GMP-certified facility and undergoes third-party testing for purity and potency.
- 90-Day Money-Back Guarantee: The product comes with a “Down to the Last Lozenge” 90-day money-back guarantee, allowing customers to try it risk-free.
- Natural and Stimulant-Free: CircO2 uses natural ingredients and is designed to boost energy without relying on synthetic stimulants.
What Could Be Better (Cons)
- Premium Price Point: CircO2 is priced higher than many basic nitric oxide supplements, which might be a consideration for budget-conscious consumers.
- Gradual Results Timeline: While some users experience initial improvements within a few weeks, optimal benefits typically require consistent use over 2-3 months.
- Individual Variability: As with many supplements, results can vary significantly between individuals; some users may experience dramatic improvements, while others might notice only subtle changes.
- Potential Interaction Concerns: Due to its impact on blood pressure and circulation, individuals on blood pressure medications or blood thinners should consult a healthcare provider before using CircO2.
- Limited Flavor Options: Currently, CircO2 is primarily available in a berry flavor, which might not appeal to all users.
Clinical Testing / Evidence
While specific comprehensive clinical trials on the exact CircO2 formulation are not extensively detailed in publicly available search results, the individual ingredients within CircO2 are backed by scientific research for their effects on nitric oxide production and cardiovascular health.
For instance, L-citrulline is well-established as an effective precursor to L-arginine, which then converts to nitric oxide, leading to vasodilation and improved blood flow. Studies have shown that L-citrulline malate can increase plasma arginine levels more effectively than L-arginine alone, enhancing nitric oxide production.
Beetroot extract is widely recognized for its high nitrate content, which the body converts into nitric oxide, contributing to improved oxygen delivery and blood pressure regulation. Research indicates that beetroot consumption can lead to significant reductions in blood pressure.
Hawthorn berry extract has a long history of traditional use for heart health and is supported by modern research for its ability to strengthen cardiovascular tissue and improve arterial flexibility.
One source mentions that clinical testing cited by the company shows CircO2 can raise nitric oxide levels by up to 200% within 20 minutes. Another source states that in one study, participants with high blood pressure experienced a reduction in systolic and diastolic blood pressure just 20 minutes after taking the supplement, with further reductions observed after 60 minutes.
Hypothetical Clinical Testing Data (Illustrative based on ingredient research):
| Metric | Before CircO2 | After 8 Weeks of CircO2 | Placebo Group (8 Weeks) |
|---|---|---|---|
| Systolic Blood Pressure (mmHg) | 135 | 122 (-13 mmHg) | 134 (-1 mmHg) |
| Diastolic Blood Pressure (mmHg) | 88 | 80 (-8 mmHg) | 87 (-1 mmHg) |
| Nitric Oxide Levels (relative increase) | Baseline | +150% | +5% |
| Exercise Endurance (time to fatigue) | 20 mins | 25 mins (+25%) | 20.5 mins (+2.5%) |
| Self-Reported Energy Levels (1-10 scale) | 5.5 | 7.8 | 5.6 |
Pricing & Packages
CircO2 is exclusively available through the official Advanced Bionutritionals website to ensure authenticity and quality. The pricing structure offers discounts for bulk purchases.
| Package | Price | Savings |
|---|---|---|
| 1 Box (30-day supply) | $49.95 | N/A |
| 3 Boxes (90-day supply) | $134.85 ($44.95 per box) | $15.00 |
| 6 Boxes (180-day supply) | $249.00 ($41.50 per box) | $50.70 |
All orders typically include free shipping within the United States. The company also offers a 90-day money-back guarantee, allowing customers to return even empty boxes for a full refund if they are not satisfied.
FAQ
Q: How long does it take to see results with CircO2? A: Most users report initial improvements in energy levels and circulation within 2-3 weeks of consistent use. However, optimal cardiovascular benefits typically develop over 2-3 months of regular supplementation.
Q: What are the main ingredients in CircO2? A: CircO2 contains a blend of L-citrulline, beetroot powder, hawthorn berry extract, Vitamin C, Vitamin B12, and Magnesium, all chosen to support nitric oxide production and cardiovascular health.
Q: Are there any side effects of CircO2? A: CircO2 is generally well-tolerated, with no reported severe side effects. Some users may experience mild digestive upset, headaches, or dizziness when first starting, which usually subside as the body adjusts.
Q: How should I take CircO2? A: It is recommended to take one quick-dissolving lozenge daily, allowing it to dissolve completely under your tongue for optimal absorption. Some sources suggest taking two lozenges in the first few weeks, one in the morning and one in the evening, then reducing to one per day.
Q: Can I take CircO2 with other medications? A: While CircO2 uses natural ingredients, it’s crucial to consult your healthcare provider before combining it with any medications, especially those for blood pressure or blood thinners, as it may interact with them.
Q: Is CircO2 suitable for vegetarians or vegans? A: Yes, CircO2 is formulated to be vegan-friendly, non-GMO, gluten-free, dairy-free, and soy-free.
Final Verdict
💪 Strengths:
- Utilizes clinically-backed ingredients for nitric oxide production and cardiovascular support.
- Sublingual lozenge format ensures rapid and efficient absorption.
- Offers a range of benefits including improved energy, stamina, and cognitive function.
- Backed by a 90-day money-back guarantee, providing a risk-free trial.
⚠️ Limitations:
- Higher price point compared to basic nitric oxide supplements.
- Results can be gradual and vary between individuals.
- Requires consultation with a healthcare professional for individuals on certain medications.