How Your Housemates Could Be Changing Your Gut Bacteria
The gut microbiome, which consists of bacteria, viruses, and fungi, is significantly shaped by our surroundings, including the people we live with. According to scientists from the University of East Anglia (UEA), sharing a home with friends or a partner may quietly be altering your gut bacteria through daily interactions.
Social Interactions Drive Microbial Exchange
Dr Chuen Zhang Lee, from UEA's School of Biological Sciences, explained that whether you're living with a partner, housemate, or family, your daily routines—such as hugging, kissing, and sharing food preparation spaces—can encourage the exchange of gut microbes. This phenomenon extends beyond just shared environments, highlighting the role of social closeness itself in shaping our internal ecosystems.
Previous studies on humans have suggested that cohabitants have a substantial influence on each other's microbial profiles, even when consuming different diets. Experts estimate that partners share approximately 30 percent of their resident microbes in the gut alone. However, new research provides unusually clear evidence of how social bonds directly drive this microbial transmission.
Bird Study Offers Clear Insights
For the study, published in the journal Molecular Ecology, researchers collected data on the Seychelles warbler, a small songbird found on Cousin Island. By gathering faecal samples over several years from breeding pairs and other birds in the group, they analysed the birds' gut microbiomes—the diverse communities of "good" bacteria in their digestive systems.
Dr Lee noted that this allowed comparisons between birds that interacted closely at the nest versus those that did not. The focus was on anaerobic gut bacteria, which thrive without oxygen, offering rare insights into how social bonds can facilitate the transmission of gut microbes.
Tracking Social Closeness and Microbial Sharing
Because the birds never leave the island, scientists could track them over their lifetimes using coloured leg rings to monitor their social interactions. The findings revealed that the more social an individual is with another, the more they share similar anaerobic gut bacteria.
Birds spending significant time together at the nest, such as breeding couples and their helpers, shared a high amount of this type of gut bacteria, which can only spread through direct, close contact. These anaerobic microbes cannot survive in open air, meaning they do not drift around in the environment but instead move between individuals through intimate interactions and shared nests.
Implications for Human Health
Researchers suggest a similar process could occur in human households, whether with housemates or spouses. This microbial exchange might actually benefit health by improving immunity and digestive function. Dr Lee emphasised that anaerobic bacteria are crucial for digestion, immunity, and overall health, forming stable, long-term colonies in oxygen-free gut conditions.
Translated into human terms, cosy nights in, shared washing-up duties, and even sitting close on the sofa may bring microbiomes quietly closer together. Sharing beneficial anaerobic bacteria could strengthen immunity and enhance digestive health across a household, subtly shaping the microscopic ecosystem inside each person.
From birth, the gut microbiome is influenced by our surroundings, starting with our mother and later by social interactions. This study underscores the profound impact of our living arrangements on our internal health, highlighting how everyday connections with those we share our homes with can have lasting effects on our well-being.
