The microbiomes of the people around you – family or friends – also affect the bacterial composition of yours, according to a new study.
- There is a sharing of microbiota between people who have social relationships, according to a new study.
- The sharing of microbiota is more important within a couple or among people living under the same roof.
- However, even when social relationships are more distant like friends of friends, there is a sharing of microbiota.
There are nearly 50,000 billion bacteria in the intestinal microbiota, or nearly one kilogram per person, according to the National Research Institute for Agriculture, Food and the Environment (INRAE).
Its composition changes throughout life, depending on diet, genetics, medical treatments, lifestyle, hormones, etc. But, according to a new study published in the journal Natureanother element could impact its composition: the surroundings.
The composition of the microbiota influenced by social relationships
During their work, the researchers studied the social relationships of 1,787 adults living in 18 isolated villages in Honduras. At the same time, they also analyzed the medical data of the microbiome of each participant. In total, the team identified 2,543 microbial species and 339,137 different strains. They then looked more precisely at the composition of the volunteers’ microbiota.
Results: the scientists observed a sharing of microbiota between participants who had social relationships. This means that the people who hung out with each other – friends or family – had similar characteristics in terms of their microbiota.
Not surprisingly, the sharing of microbiota was greater within a couple or among people living under the same roof. Indeed, the time spent together, particularly during meals, but also the way of greeting each other (handshakes, kisses or hugs) increased this influence of one on the other.
Researchers also noted high rates of sharing “good bacteria” with friends, and even second-degree social relationships (like friends of friends).
A microbial sharing which increases over time
“We found evidence of microbiota sharing between people who are not part of the [même] family and who do not live together, even after taking into account other factors such as diet, water sources and medications, indicates Francesco Beghini, one of the authors, in a press release. The sharing of microbiota was [la meilleure information pouvant prédire] of the social relationships of people in the villages we studied, much more than characteristics like wealth, religion or education.“
Does this phenomenon of microbial sharing increase over the years? Yes, since the microbiota evolves throughout life, influenced by the people we interact with on a daily basis. To measure this, the team again studied the microbiomes of a subset of 301 participants from four of the villages, two years after the initial experiment.
The researchers observed that the more volunteers were socially connected with the groupthe more similar the composition of the microbiota had become. “Think about how different social niches form at a place like Yale, says co-lead author Jackson Pullman, a 2023 Yale College graduate. You have friend groups centered around things like theater, team , or physics majors. Our study indicates that the people who make up these groups may be connected in a way we’ve never thought before: through their microbiomes.”
“The fascinating thing is that we are so interconnected. These links go beyond the social level to reach the microbial level”, he adds.
