CO₂ Is Not a Waste Gas — It’s Your Oxygen’s Guardian
Most people have been taught that carbon dioxide (CO₂) is simply a waste gas we must eliminate by breathing more.
In reality, CO₂ is one of the most important metabolic signals in the human body — especially for the brain, heart, fertility system, and mitochondrial energy production.
Every cell in your body relies on a continuous flow of:
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Glucose (fuel)
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Oxygen (combustion)
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Thyroid hormone T3 (metabolic accelerator)
Inside the mitochondria — the tiny energy factories within each cell — these three inputs combine to produce:
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ATP, our usable energy
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CO₂, which stabilises oxygen delivery and blood flow
CO₂ is not a sign of dysfunction.
It is the natural result of healthy glucose oxidation.
Rather than being dangerous, CO₂ allows oxygen to be safely used inside cells.
Low CO₂ — usually from chronic over-breathing — makes oxygen supply worse, not better.
The Misunderstanding: Hyperventilation Does Not Improve Oxygenation
Many yoga classes, breathwork schools, meditation apps, and gym routines teach people to:
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breathe more deeply,
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breathe more frequently,
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induce breathlessness,
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“oxygenate the brain” through rapid breathing.
This sounds logical — but physiology says the opposite.
When you breathe too much or too fast:
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CO₂ drops,
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blood vessels constrict,
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oxygen becomes tightly bound to haemoglobin,
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less oxygen reaches your tissues.
This means you can feel light-headed even while oxygen saturation is 98–100% — because oxygen cannot get released into the brain.
This is why chronically breathless people, anxious patients, and hyperventilators often feel dizzy despite “good oxygen levels”.
True oxygenation has nothing to do with breathing harder.
It depends on the balance between oxygen and CO₂.
The Bohr Effect — Explained Simply
The Bohr Effect, discovered in 1904, describes how CO₂ controls oxygen delivery.
Here is the friendly version:
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Oxygen travels through your blood attached to haemoglobin.
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Haemoglobin will only release that oxygen when CO₂ levels are present.
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More CO₂ → more oxygen released to the tissues
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Low CO₂ → haemoglobin holds oxygen too tightly
So the key to better oxygenation is not more oxygen…but more tolerance to CO₂.
CO₂ is the key that unlocks oxygen from haemoglobin.
When CO₂ drops (through over-breathing):
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the key is lost,
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oxygen cannot be released,
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cells become oxygen-deprived even with normal lung function.
This is why controlled breathing, nasal breathing, and improving CO₂ tolerance increases:
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mental clarity
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emotional regulation
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physical stamina
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fertility and hormonal resilience
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wound healing
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metabolic energy
Why Babies Heal Quickly — Their CO₂ Levels Are Higher
Newborns have naturally higher CO₂ levels than adults.
This is one reason babies:
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heal wounds faster,
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oxygenate tissues more efficiently,
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stay metabolically “warm” and flexible,
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have strong microcirculation.
In many ways, high CO₂ tolerance is a sign of metabolic youthfulness.
Adults with low CO₂ tolerance — often due to stress, chronic anxiety, mouth breathing, asthma, or over-training — lose that metabolic advantage.
Why Improving CO₂ Tolerance Creates More Energy and Calm
When you gently retrain your breathing to raise CO₂ tolerance, several benefits emerge:
1. Better oxygen delivery to brain, heart, and reproductive organs
More CO₂ → better oxygen release via the Bohr Effect.
This supports:
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clearer thinking
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deeper sleep
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improved libido and reproductive function
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better endometrial oxygenation
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improved egg quality via mitochondrial efficiency
2. A calmer, more stable nervous system
CO₂ activates the parasympathetic (vagal) system and quiets the fight-or-flight response.
This lowers:
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anxiety
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panic
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breathlessness
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sympathetic dominance
3. Improved metabolic rate and mitochondrial efficiency
Healthy mitochondria produce more ATP — and more CO₂.
Raising CO₂ tolerance supports:
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better glucose oxidation
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lower lactate accumulation
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stronger thyroid hormone signalling
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steadier energy throughout the day
4. Better circulation and warmer hands/feet
CO₂ is a natural vasodilator
Low CO₂ = cold extremities, scalp tension, migraines
Improved CO₂ = better microcirculation everywhere
5. Enhanced healing, repair, and tissue oxygenation
Higher CO₂ → better delivery of oxygen to damaged tissues
This echoes the physiology of babies and young children
6. Reduced inflammation caused by poor breathing habits
Chronic over-breathing reduces CO₂ and increases sympathetic tone, which contributes to inflammatory signalling.
Raising CO₂ tolerance shifts the physiology back to a calmer, reparative mode.
7. Improved exercise performance
When CO₂ tolerance rises:
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you feel less breathless
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your breathing slows
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your endurance improves
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lactate rises more slowly
Athletes who train their CO₂ tolerance often report the ability to “stay relaxed at higher intensities”.
What Low CO₂ Tolerance Looks Like
People with low CO₂ tolerance often experience:
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frequent sighing
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mouth breathing
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shallow chest breathing
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anxiety spikes
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dizziness or tingling
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waking up at night
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feeling breathless during light activity
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cold extremities
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brain fog despite “normal oxygen saturation”
These are not signs of weak lungs — they are signs of overly sensitive CO₂ sensors.
How to Improve CO₂ Tolerance
You do not need extreme breathwork.
You do not need to create strong air hunger.
And you should never force breath holds during pregnancy.
The safest, most effective methods include:
1. Nasal-only breathing all day
Nasal breathing maintains higher CO₂ and warms/humidifies air.
2. Slow, silent, low-volume breaths
Gentle breathing creates mild CO₂ rise — the ideal training stimulus.
3. Light breath holds after a normal exhale
5–10 second pauses (not stressful) retrain the chemoreceptors.
4. Exhale-lengthening
Let exhalation become slightly longer than inhalation.
5. Reduce over-breathing caused by stress, anxiety, or posture
Improving rib mobility and diaphragmatic movement helps dramatically.
Why This Matters for Fertility & Hormonal Health
From a reproductive perspective:
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the ovaries, uterus, testicles, thyroid gland, adrenal glands, and brain all depend on microcirculation and stable oxygen delivery
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chronic stress breathing patterns reduce that supply
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higher CO₂ tolerance improves local perfusion and mitochondrial resilience
This explains why many patients report:
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steadier cycles
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better sleep
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improved sense of well-being
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fewer panic episodes
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greater stamina
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warmer pelvic region
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better libido
These aren’t “breathwork miracles” — they are straightforward oxygen-delivery physiology.
Supporting the London Community
At Dr Ryu Natural Medicine in Wimbledon, South-West London, breath physiology is an integral part of how we support:
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fertility enhancement
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IVF optimisation
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hormonal balance
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stress and anxiety recovery
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metabolic health
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long-COVID breathing rehabilitation
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chronic fatigue
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postnatal recovery
Whether you are trying to conceive, managing stressful life phases, or rebuilding energy, correcting breathing patterns and supporting CO₂ tolerance is one of the most accessible, gentle, and evidence-informed interventions.
