Description
NutraBio PeakO2
2 grams of PeakO2 per serving — a blend of six organic mushrooms — with no fillers or proprietary blends. Stimulant-free, 60 servings.
Six mushrooms, and the dose matches the research
PeakO2 is a defined blend of Cordyceps militaris, Reishi, King Trumpet, Shiitake, Lion's Mane and Turkey Tail, all organically grown.
The dose is the part worth noting. 2 grams is the amount used in the research on this ingredient — which is unusual. Mushroom blends appear in a great many pre-workouts at 50 to 200mg, a small fraction of what was actually studied.
When we say a dose is clinical, this is what we mean: the amount in the tub matches the amount in the trials.
What the research actually looked at
PeakO2 is one of the more interesting ingredients in this category because its research is about oxygen utilisation rather than stimulation.
The studied outcomes include power output, oxygen uptake, time to exhaustion and lactate accumulation.
Why that matters: most performance supplements work by making you feel more capable. This one is examined for whether your body uses oxygen more efficiently — which is a physiological measure rather than a subjective one, and it puts PeakO2 in the same conceptual family as dietary nitrate rather than caffeine.
Cordyceps is the ingredient most associated with that effect, with a research history in exercise capacity and oxygen efficiency.
Adaptogens — what the word means, honestly
"Adaptogen" gets used loosely, so it is worth being precise.
An adaptogen is a compound proposed to help the body resist stressors — physical, chemical or biological — by supporting a return to balance rather than pushing in one direction. It is a category description, not a proven mechanism.
Our honest read: the concept is legitimate and the mushrooms here have long histories of traditional use, but adaptogen research is generally softer than research on single isolated compounds. Where PeakO2 is on firmer ground is the specific exercise performance work done on this exact blend at this exact dose.
Buy it for the oxygen utilisation research, not for the word adaptogen.
You will not feel it, and that is expected
Worth saying plainly, because it is the most common disappointment with this product.
PeakO2 contains no stimulants. There is no rush, no focus surge and no tingle. It works — if it works for you — by improving how efficiently your body uses oxygen during effort, which shows up as being able to do slightly more before fatigue rather than as a sensation.
Give it several weeks. The research protocols run over weeks of consistent daily use, not single doses.
Specs
| PeakO2 | 2g per serving (1 scoop) |
| Mushrooms | Cordyceps, Reishi, King Trumpet, Shiitake, Lion's Mane, Turkey Tail — all organic |
| Servings | 60 |
| Stimulants | None |
| Flavour | Unflavoured |
| Label | Fully disclosed, kosher, third-party tested |
Also available in capsules — three capsules is one serving, if you would rather not mix a powder.
How to take it
- One scoop (2g) mixed into any beverage, once or twice daily.
- On training days: one serving before exercise and one after.
- On rest days: two servings spread through the day.
- Take it daily. The research involves consistent use over weeks rather than acute dosing.
- Stacks with anything — no stimulants, so it goes alongside your pre-workout without adding to your caffeine total.
Who this is for
- Endurance athletes — the oxygen utilisation and time-to-exhaustion research is the strongest case
- Anyone doing long or repeated high-intensity efforts
- People who cannot take stimulants but want a performance ingredient
- Anyone who wants a mushroom blend at the researched dose rather than 100mg in a pre-workout
- People training at altitude or in demanding conditions
Who this is not for
Anyone expecting to feel something. There are no stimulants here, and the effect is physiological rather than perceptual.
If you want an acute performance boost today, caffeine has vastly more evidence and costs a fraction as much.
Anyone with a mushroom allergy.
If you want lion's mane specifically for cognition, our standalone Lion's Mane gives you 500mg rather than a share of a 2g blend.
Speak to your doctor first if you take blood thinners or immunosuppressants — some mushroom compounds affect clotting and immune signalling.
Not for anyone under 18, pregnant or nursing.
Stack it with: Mega Beets — both work on oxygen delivery and utilisation by different routes, which is a genuinely complementary pairing for endurance.
Frequently asked questions
What is in PeakO2?
Six organic mushrooms: Cordyceps, Reishi, King Trumpet, Shiitake, Lion's Mane and Turkey Tail, at a combined 2g per serving.
Is 2g the right dose?
Yes — it matches the amount used in the research on this blend. Pre-workouts containing 50 to 200mg of mushroom blend are well below that.
What does it actually do?
The research examined oxygen uptake, power output, time to exhaustion and lactate accumulation — physiological measures rather than subjective ones.
Will I feel it?
No. It contains no stimulants and works over weeks of consistent use rather than acutely.
How long before it works?
Several weeks. Research protocols use consistent daily dosing rather than single servings.
Can I take it with my pre-workout?
Yes. It is stimulant-free and adds nothing to your caffeine total.
What is an adaptogen?
A compound proposed to help the body resist stressors and return to balance. It is a category description rather than a proven mechanism — buy this for the exercise research, not the word.
Powder or capsules?
Same blend. Three capsules equals one 2g scoop. Powder is cheaper per serving; capsules are easier to travel with.
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