Wim Hof's method sounds like hype. In a lab, it did something.
People say: “You can control your immune system” We read the study.
Randomised controlled trial (RCT). 24 people. 10-day training program (4 intensive days in Poland + daily home practice 5-9 days), then one 8-hour endotoxin experiment day.
A trial. Chance decided who did what.
Who: Healthy, nonsmoking Dutch male volunteers (median age 24 trained vs 22 control, range 19-27) with no prior meditation experience; 12 trained vs 12 controls underwent endotoxemia (30 enrolled: 18 trained, 12 control)
- Inflammation signals~half
- Flu-like symptoms (self-rated)-56%
- Adrenaline, during breathingway up
More to know, from our read of the paper:
- Tiny trial: 12 trained vs 12 controls, all young healthy men; no women, no older people, no patients
- The intervention was a COMBINATION (meditation + cold exposure + breathing + strength exercises); authors think breathing drove it but write it 'cannot be ruled out that other elements of the training' contributed, and the design cannot identify which component raised epinephrine
- Lab model only: a single IV injection of purified E. coli endotoxin (2 ng/kg), not a real infection; authors did not measure immune parameters outside endotoxemia
- No blinding reported; controls got no training or sham activity; Wim Hof himself coached the trained group during the experiment day
- 3 control subjects were excluded and replaced after a presumed endotoxin dosing error (abnormally low responses)
It dampened a lab reaction. Not proven against real illness.
- It was the whole methodThe study couldn't tell which part did it.
- Never do it in waterOxygen dropped to ~50% during breath holds.
- Not a treatmentOnly 24 healthy young men, in a lab.
A randomized trial in 24 healthy young Dutch men. 12 trained for 10 days with Wim Hof (breathing, cold exposure, meditation); 12 did no training. Then everyone got an injection of bacterial endotoxin, a lab model that causes flu-like symptoms. The trained men had much more adrenaline, about half the inflammation signals (TNF-α 53%, IL-6 57%, IL-8 51% lower), and 56% fewer self-rated symptoms. It was a combination of methods, so the study can't say which part worked, and it didn't test real infections or disease.
Kox et al. (2014). Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans. Proceedings of the National Academy of Sciences (PNAS).
Design: Randomised controlled trial (RCT) · randomized controlled trial (lab endotoxin model)
Goals:
We read the abstract and the full text of this paper and checked every number on this page against it (16 facts, checked on 2026-09-27). The study design is named above. Cohort and other observational studies are described as linked, not proven. Found an error? Email theis@onestudyaday.com.
Join the waitlist: one checked study a day for your goal, by email
Pick up to three goals. We email you once when the daily study starts. The goals for this study are ticked already.