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Bryan Johnson Psilocybin Experiment: 249 Biomarkers, a Metabolic Reset
Posted under: Pioneers
Published: March 25, 2026 · Psilocybin Science · 6 min read
Bryan Johnson took magic mushrooms — twice. His team tracked 249 health markers before and after each session. The Bryan Johnson psilocybin experiment is the most measured psychedelic self-test ever made public. Some results were very positive. One result shocked even his own team.
Who is Bryan Johnson?
Bryan Johnson is an American entrepreneur. In 2013, he sold his company Braintree to PayPal for $800 million. Since then, he has one main goal: to slow down ageing and live as long as possible.
He tracks his health every single day. Sleep, heart rate, testosterone, sperm quality — he measures it all. He calls this his Blueprint Protocol. He is known for unusual experiments. He has tried blood transfusions and other extreme health treatments.
In late 2025, he turned his attention to psilocybin — the active compound in magic mushrooms. "What if psychedelics are also a longevity treatment?" he asked during a live session watched by over a million people.
What did he actually do?
The Bryan Johnson psilocybin experiment had two sessions. In the first, he took 25 mg of dried magic mushrooms. In the second, he took 28 mg. Both sessions took place at a licensed psilocybin centre in Oregon, USA.
His team ran blood tests, saliva tests, and temperature checks at three moments: just before the first session, three days after the second session, and again 20 days later. He also wore a $50,000 brain-scanning helmet during the sessions to track what was happening in his brain in real time.
What is neuroplasticity? It means the brain can grow new connections. Psilocybin seems to help this process. Scientists think this is why it can help with depression and addiction.
The good news: blood sugar reset
The Bryan Johnson psilocybin experiment produced some striking results. His blood sugar control improved a lot. Before the experiment, he was already in the top 2% of men aged 18–25. After the sessions, he moved to the top 0.2%. Johnson calls this a "metabolic reset".
His cortisol levels — a stress hormone — went up by 100–300% during the peak of the psilocybin experience. This matches what other clinical studies have found. His total testosterone also went up by 30% in the three days after the second dose.
Johnson sees these results as proof that psilocybin could be a longevity tool. Want to learn more about how this works? Read our article on how psychedelics work in the brain.
The big surprise: the Bryan Johnson psilocybin experiment and sperm quality
This is the finding that got the most attention. Johnson's sperm quality dropped sharply after the sessions. His motile sperm count fell from the 99.6th to the 77.7th percentile. He posted this result on LinkedIn and X on March 19, 2026. He called it a possible "first-in-human observation" — meaning no one had ever reported this before.
Here is what the data showed:
| What was measured | 3 days after dose 2 | 20 days after dose 2 |
|---|---|---|
| Sperm movement (motility) | −51% | Almost back to normal (−2%) |
| Total sperm count | −2% (almost no change) | −38% (delayed drop) |
| Total moving sperm | −52% | −39% (partly recovered) |
| Normal sperm shape | −50% | Almost back to normal (−10%) |
Johnson points out that his total moving sperm count stayed above 50 million. Doctors consider this level good enough for fertility. So this was not a fertility crisis. But the drop was large and unexpected.
Why did sperm quality drop?
Johnson's team offers two possible reasons:
1. Psilocybin acts on sperm cells directly. Sperm cells have serotonin receptors — specifically a type called 5-HT2A. Psilocybin binds strongly to this receptor. A recent study found that blocking this receptor reduced sperm movement. This suggests that activating it could do the same.
2. Free testosterone fell. Total testosterone went up by 30%. But a protein called SHBG (Sex Hormone Binding Globulin) also rose by 37%. SHBG grabs testosterone and makes it inactive. So even though total testosterone was higher, the amount the body could actually use went down by 24%. This may have slowed sperm production.
Keep in mind: This is one person's experiment. It was not a controlled scientific trial. No clinical study has confirmed this effect in other people yet. Johnson himself says it is only a "possible" first observation — not a proven fact.
Does psilocybin affect fertility?
We do not know yet. Johnson's numbers never dropped below what doctors consider a safe level for fertility. Most effects — like sperm movement and shape — recovered within 20 days. The drop in total sperm count at day 20 was likely because sperm take about 74 days to develop. So the effects may still be reversing at that point.
If you are trying to have a child, it makes sense to be careful with high doses of psilocybin. Talk to a doctor first. For people interested in microdosing — which uses much smaller doses — the effects would likely be very different. But no research on microdosing and fertility exists yet.
Could psilocybin be a longevity tool?
The Bryan Johnson psilocybin experiment fits into a growing area of research. Scientists are now asking whether psilocybin does more than treat mental health. Could it also slow ageing? Could it improve metabolism? Could it reduce inflammation?
Johnson's results point in an interesting direction. His blood sugar and brain health markers improved a lot. These findings match early lab studies in animals. Whether the same happens in all humans is still unknown. But the results are strong enough to start proper clinical trials.
Psilocybin research is moving fast. We recently wrote about the Johns Hopkins study showing psilocybin is six times more effective than nicotine patches for quitting smoking. We also covered the JAMA study on psilocybin use after decriminalisation in Oregon and Colorado. The science is clear: psilocybin affects the human body in ways we are only starting to understand.
What happens next?
Johnson shared both the good and the bad results openly. That honesty is valuable. It gives other scientists a starting point for new studies. Right now, there is no clinical trial looking at psilocybin and male fertility. Johnson's data could help make one happen.
The Bryan Johnson psilocybin experiment raised important questions. How does psilocybin affect hormones? How long do the effects last? Do they differ between people? These are questions science needs to answer.
Want to know if magic mushrooms are legal in your country? Or curious about what psilocybin does to the brain? Explore our blog for more.
Ready to explore psilocybin the right way? See our full range of magic truffles and grow kits — trusted by explorers across Europe since 2008.
⚠️ Important: Always check the laws in your country before buying psilocybin products. Rules are different everywhere. We always encourage safe and responsible use.
March 25, 2026