Studying Acute Mountain Sickness on the Trail and in the Lab

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• Joyce Pritchett- [email protected]

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• Stephanie Healey- [email protected]

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Oxygen is critical to life. When levels of oxygen change, it can have immediate and lasting impacts on a person's health.

Tatum Simonson, PhD, associate professor of medicine and John B. West Endowed Chair in respiratory physiology in the Division of Pulmonary, Critical Care, Sleep Medicine & Physiology at the University of California San Diego School of Medicine, has studied the effects of altitude on people across the globe. Her research hopes to uncover the genetic and epigenetic factors that protect against-or contribute to-low-oxygen health issues. Over time, this work could lead to better ways to treat or prevent a wide range of breathing problems.

"There is a lot of variability in how people respond to altitude," said Simonson. "You can be an Olympic athlete and still suffer from AMS or other life-threatening illnesses when you are at higher altitudes. Individual biology, experience, health, age and background all shape how the body responds-making it essential to approach high-altitude exposure with personalized awareness rather than one-size-fits-all assumptions."

The study found that people who received probiotics had better oxygen levels during the day and at night, and experienced fewer symptoms of AMS than those who took a placebo. Overall, the probiotic helped participants acclimatize more effectively to high altitude, suggesting it could be a simple, non-invasive way to support acclimatization to altitude. And unlike medications currently available, the probiotic was really fast acting.

"Currently, there are very few non-drug options to help people cope with low oxygen levels, especially at high altitude," said Simonson. "This research suggests that a probiotic-already known to have many health benefits-may be helpful in this setting. We hope these findings can extend to other areas of research and eventually benefit patients with low oxygen levels in places like the ICU or emergency department, as well as people with conditions such as sleep apnea or chronic lung disease."

While the initial study on probiotics resulted in compelling results, Simonson teamed up with Sela Salzman, MS, lead researcher for the female athlete program at UC San Diego, and others from the Wu Tsai Human Performance Alliance, to create an educational video showcasing practical applications of her research translating to Salzman's domain of performance.

"We wanted to bring the science to people in a way that's more engaging-especially for those who don't usually turn to scientific publications," said Salzman. "For me as a researcher, there's real value in learning from what Tatum is doing and translating those insights into daily life. It's also a chance to showcase the exciting work she's leading at UC San Diego, not just around optimizing performance, which is my focus, but overall health as well."

To augment the probiotic study and provide an educational opportunity to bring AMS research to life in a real-world setting, Salzman recorded vlog-like videos as she attempted to summit Mount Whitney. Located in the Sierra Nevada mountain range, Mount Whitney rises to 14,505 feet-the highest peak in the contiguous United States. Salzman, a self-described planner, met with Simonson to learn everything she could about AMS including how to recognize it, respond if symptoms appear and what to do if symptoms progressed to dangerous levels.

Armed with a video camera, Salzman and a group of hikers took on the challenge in July 2025. She recorded video clips of her preparation at home and throughout the journey all the way to the summit of Mount Whitney and back down, noting how she felt using the Lake Louise Mountain Sickness scale, which helps score AMS severity.

"Going into the hike, I was nervous about the altitude, but Tatum helped put my mind at ease and guided my preparation," said Salzman. "AMS affects people so differently, which is why this project was so exciting. The value comes from understanding the underlying mechanisms and figuring out what we can do, especially since there's no one-size-fits-all solution."

Together, Simonson and Salzman's work highlights how science can move beyond the lab and into everyday experience. By combining rigorous research with real-world storytelling, they are helping people better understand how the body responds to low oxygen. While more research is needed, these efforts point to potential practical and accessible ways to support health whether on a mountain trail, in a hospital setting or in daily life.