A Mount Royal University study is shedding light on how Tibetan highlanders adapt to high-altitude settings.

The study, published in the Proceedings of the National Academy of Sciences, studied blood acid-base acclimatization responses to incremental ascent in lowlanders and Tibetan highlanders (otherwise known as Sherpas). The team recruited 14 Tibetan highlanders who haven’t been in high altitudes for over a year and analyzed blood samples at various altitudes. The team then compared these blood samples with those collected from people with Western European ancestry (called lowlanders in the study).

According to lead researcher Trevor Day, the body will protect oxygenation at higher altitudes by breathing more. However, that drives carbon dioxide levels down, which will affect the acid-base balance in the body’s bloodstream. The kidneys will step in and try to fix the imbalance.

Day said that the lowlanders’ blood will stay alkalotic and out of balance forever, indicating an altitude threshold from which their blood pH can’t acclimate.

However, Tibetan participants had a more rapid and larger magnitude kidney response, and their blood pH levels were back to normal after eight or nine days in higher altitudes.

“Now we don’t know what it looks like if you say, for a month, two months, or a year. That’s another study, and those are hard studies to do, as you can imagine,” Day told LiveWire Calgary.

“But it suggests that active acclimatization in Sherpa, from a renal or kidney perspective, is more powerful, and that’s kind of the novel finding here, and it adds another organ of interest to studying high altitude acclimatization in lowlanders versus Sherpa.”

Day also suggested there may be evolutionary pressures that drove differences in kidney function between Tibetan highlanders and lowlanders.

“We know that Sherpas are incredible at living, working and reproducing at high altitudes. That’s where their ancestral population is. The Tibetan Plateau is something between 4,000 and 4,500 metres [above sea level],” he said.

“It suggests there’s selective pressure, evolutionary pressure, on this population that drove differences in kidney function. This opens up a whole new avenue of investigation of studying the kidneys of Sherpa … I think there’s work to be done in genetics to see if there are differences in genes between Highlander populations and lowlanders as well. That might kind of suggest that the genetic underpinning of this work.”

Inspired by the mountains

Day, who has a background in respiratory physiology, said he got the idea to study Sherpas from the mountains.

“I got inspired by big mountains and stories from big mountains in my undergraduate degree, where I was doing a lot of trekking and scrambling. I read John Krakaeur’s book Into Thin Air during a course in environmental physiology that I took [during my undergraduate degree] and really fell in love with the topic, never thinking I’d ever go to Nepal,” he said.

“Then, in 2012, I was asked to join an expedition led by a collaborator from the University of British Columbia, and we went to the Everest region, and I got to see Kathmandu and the Everest base camp and Everest for myself. That was my first time there doing some research in Nepal.”

Since then, Day said he’s organized his own expeditions. He went back to Nepal in 2016, 2017 and 2018 for one of his own research projects. In 2019, he went on an expedition to the White Mountains in California in collaboration with the University of Calgary. Last year, he went to Bolivia for an expedition in La Paz.

Day said he’s been on seven organized expeditions in total.

“It’s just become a bit of an interest of mine, of how the human body responds to the low oxygen that’s present when you ascend to high altitude,” he said.

“What’s cool about it is it’s truly integrated physiology. You have to think about how all the organ systems interact in response to either acute hypoxia or low oxygen. Or you how you acclimatize over, you know, days to weeks, or more recently, how Indigenous highlanders might respond differently.”

An interdisciplinary research project

Day said the research was interdisciplinary because it combines chemistry, biochemistry, biology, physiology, anthropology and environmental science together.

While the topic may be seen as “niche” to some, he said the knowledge may help people plan safer expeditions, safer ascent profiles and better understand occupational stress in miners, climbers and guides.

“Understanding the integrative responses to high altitude stress has a lot of broader applications for lots of different people, outside of just understanding how Indigenous highlanders might be different. Just understanding how humans respond over weeks, or genetic changes in our population. This kind of continuum of exposure can lead to different kinds of responses,” he said.

“It’s just a basic science understanding. Now we know that there are differences in populations that are interesting and new.”

Day said the knowledge may also be used in clinical applications.

“I think there’s an analogous comparison there, from a clinical population of understanding what happens if you breathe too much. You have low [carbon dioxide] and you end up with sleep apnea. That might help us understand another population that has the same kinds of problems, even at sea level,” he said.

Day said he is planning on studying Indigenous highlanders in the Andes to see if there are differences in kidney function there. However, expeditions like this are often long, expensive and logistically intensive.

On the expedition to study Tibetan highlanders, Day had to assemble several American and Canadian grants, a team of undergraduate students, and a team of collaborators to help navigate ethics, recruit participants and travel before stepping on a plane. The team also had to work in austere conditions.

“It’s tricky to recruit people generally for human physiology studies. But it’s another thing altogether when you add another ethnic group who are going to take time away from their lives and come up the hill for a couple of weeks and be tested again. So, we’re always very grateful to our participants for saying yes to this kind of stuff because it’s a big investment in time and energy to be a participant in these studies,” he said.

But being able to see a beautiful side of the world and mentor undergraduate students made the trip worth it, he said.

“The first two co-authors on our paper were Mount Royal undergraduate students. I’m really proud of them for their contributions. It helps their career a lot. They’re now off to graduate and professional programs. But everyone, every trainee on the expedition, really benefits from these kinds of things, in terms of exposure to people from all over the world, learning how to do science under difficult conditions, and making new friends, and then, ultimately, is what it’s all about, is relationships,” Day said.