Couples Share a Surprising Percentage of Gut Bacteria That May Impact Health

From birth, interaction with our mother seeds the human microbiome with microbes that help immune and digestive development.

People you live with strongly influence your microbiome; partners share around 30% of resident gut microbes (range 13–30%).

That sharing range persisted when diet was factored out, and cohabiting couples have greater gut microbial diversity than people living alone.

Greater microbial diversity correlates with lower risk of IBS, cardiovascular diseases, and possibly high blood sugar, though some shared species have varying health effects.

Oral microbes are shared via saliva—for example, a 10-second kiss can transfer up to 80 million bacteria—and Ruminococcus species among shared bacteria include both beneficial and potentially harmful links (diabetes, IBS).