How Probiotics Can Help Climbers Adjust to High Altitudes, According to Science

April 7, 2026

One afternoon in August 2024, high in California’s White Mountains, Tatum Simonson, an associate professor and physiologist with expertise in altitude adaptation at the University of California, San Diego, and her volunteers shuffled into Barcroft Station. The off-grid research outpost sits at 12,470 feet amid jagged peaks and stark scree slopes along the eastern edge of the Sierra Nevada. Within hours of arrival, some participants felt the physical impacts of reaching the high-elevation lab. Pounding headaches, the nausea creeping up, the restless sleep—all of which are telltale signs of altitude sickness (a condition that occurs when you rapidly ascend without giving your body enough time to adjust to lower amounts of oxygen in the atmosphere as your elevation increases).

For decades, mountaineers have relied on little more than slow ascents and sometimes a prescription drug called acetazolamide, better known as Diamox. But Simonson wondered if they were overlooking another factor: the gut.

Bacteria, fungi, and other microbes make up roughly half of the cells in our bodies, and some estimates suggest their genes outnumber our own by about 100 to one. When oxygen runs low at altitude, intestinal microbiota can feel the stress too, potentially shaping how the body senses and responds to low oxygen. Outside