What is already known on this topic
Human populations such as Nepal’s Sherpa have adapted to survive at high altitudes, where oxygen levels can be much lower and food can be scarcer than lowland areas. Living at high altitudes could also affect the gut microbiota composition of these populations.
What this research adds
Researchers analyzed the microbiota of four populations living at variable degrees of altitude: the high-altitude Sherpa and low-altitude Tamang people from Nepal, the high-altitude Aymara people from Bolivia, and a low-altitude population of European ancestry. Sherpa and Aymara had similar microbial profiles, which they didn’t share with low-altitude populations. By supplying key metabolic compounds, the microbes might help these populations to adapt to the environmental and nutritional challenges associated with high altitudes.
The results support the idea that symbiosis between microbes and their human host has positive effects from an evolutionary perspective.
The gut microbes of native Himalayan and Andean people could have helped them to survive at high altitudes, where oxygen levels can be much lower and food can be scarcer than lowland areas. The findings, published in the Journal of Anthropological Sciences, support the idea that symbiosis between microbes and their human host has positive effects from an evolutionary perspective.
Previous studies have analyzed the effect of high altitudes on the gut microbiota of populations from different places across the Tibetan Plateau. But mingling between high-altitude Tibetan people and low-altitude populations from East Asia has hindered the identification of microbial features that may have facilitated adaptation to high altitudes.
To identify such microbial features, a team of scientists led by Andrea Quagliariello at the Bambin Gesù Children’s Hospital and Monica Di Paola at the University of Florence set out to analyze the microbiota of four populations living at different altitudes.
The researchers collected microbiota samples from two populations that live at high altitudes: the Sherpa, who inhabit the southern slopes of the Himalayan mountain range in Nepal, and the Aymara, who live on the Bolivian Andes. Then, the team compared the microbiota of these populations with those of two groups that live at low altitudes: the Tamang people from Nepal, who live at no more than 2,000 meters above sea level, and a population of European ancestry living in Italy.
Sherpa and Aymara people had similar microbial profiles, which they didn’t share with low-altitude populations. For example, Spirochaetes and Elusimicrobia bacteria were enriched in samples from high-altitude populations, but they were not so abundant in samples from Tamang people.
Treponema and Butyrivibrio were also among the bacteria that characterized the microbiota of high-altitude Sherpa and Aymara. In particular, Sherpa had a high abundance of Bifidobacterium adolescentis, Rikenellaceae, Treponema and Elusimicrobiaceae in their guts. The microbiota of low-latitude Tamangs was instead characterized by Enterobacteriaceae, Blautia producta, Eggerthella lenta, Lactococcus garviae and Bacteroides plebeius.
A little help from microbes
The bacterial genomes of Sherpa and Aymara share several functional pathways that distinguish them from those of the Italian population. Compared to the bacterial genomes of this group, those of high-altitude people expressed more genes involved in fatty acids production, vitamin and amino acids metabolism, as well as energy production.
Treponema and Butyrivibrio are known to produce high levels of short-chain fatty acids, which are important for energy yield and are associated with low blood pressure. The production of short-chain fatty acids could thus help to reduce people’s susceptibility to mountain sickness, facilitating the adaptation to high altitudes, the researchers say.