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Updated: May 6, 2026
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Applying Advanced In Vitro Culturing Technology to Study the Human Gut Microbiota
Published on: February 15, 2019
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Gut Microbiota Dynamics During Extreme Altitude Climbing: A Longitudinal Case Report
Jesús Álvarez-Herms1,2, Kilian Jornet3, Martin Burtscher4
1Phymolab, Exercise Physiology Laboratory, Collado Hermoso (Segovia), Spain.
High Altitude Medicine & Biology
|November 20, 2025
Summary
Extreme altitude climbing significantly alters gut microbiota (GM), decreasing diversity and increasing pathogenic bacteria. A healthy GM profile may enhance tolerance to hypoxia and prevent altitude sickness.
Area of Science:
- Human physiology
- Microbiology
- Altitude medicine
Background:
- Extreme altitude climbing presents significant physiological challenges.
- Understanding the impact of high altitude on the human gut microbiome is crucial for mountaineer health.
Purpose of the Study:
- To investigate the dynamic changes in gut microbiota (GM) and physiological responses during a 4-week extreme altitude expedition.
- To correlate GM alterations with physiological changes and health complications at varying altitudes.
Main Methods:
- A longitudinal case study of a world-class mountaineer during a 4-week stay at 3,600–4,200 m with rapid ascents to extreme altitudes (up to 8,400 m).
- Monitoring of physiological parameters including hypoxemia, hyperglycemia, ketoacidosis, and sympathetic dominance.
- Analysis of gut microbiota composition and diversity (Shannon index).
Main Results:
- Physiological stress markers (hypoxemia, hyperglycemia, ketoacidosis, sympathetic dominance) increased proportionally with altitude.
- Gut microbiota diversity decreased significantly (Shannon index from 5.88 to 4.56) during acclimatization.
- A transient 2,800% increase in pathogenic *Ruminococcus gnavus* was observed, coinciding with impaired health and gastrointestinal/respiratory issues.
Conclusions:
- Gut microbiota composition is significantly altered by extreme altitude exposure.
- A healthy GM profile, rich in mucolytic and short-chain fatty acid-producing bacteria, may enhance hypoxic tolerance.
- Maintaining a favorable GM may reduce the risk of gut leakage, systemic endotoxemia, and acute mountain sickness.
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