Overview
- The study, which was published June 15, found that people who live together share about 19% of gut microbial strains and 26% of oral strains on average, with romantic partners sharing roughly 44% of oral strains.
- Researchers analyzed strain-level metagenomic data from 430 people in 207 households in Italy and Fiji to compare exact microbial strains between cohabitants and non-cohabitants.
- The team documented an oral–gut axis where microbes from the mouth can seed the gut, for example through swallowing saliva, helping explain similarities across body sites.
- The microbes estimated to be most transmissible were enriched for markers linked to type 2 diabetes, poorer cardiometabolic profiles, colorectal cancer‑associated species, and several opportunistic pathogens, though the study is observational and does not prove cause.
- Authors say the findings could help design better probiotics and fecal microbiota transplant approaches by targeting transmissibility traits, but they caution that more work is needed to test causation, control for shared diet and environment, and validate results beyond Italy and Fiji.