80 million bacteria exchanged with a kiss!

The more you kiss your partner, the more you share bacteria, according to a Dutch study.


Researchers have long been fascinated by the act of kissing. Humans are the only mammals on the planet to “French kiss.” Is it an indication of compatibility between two people? An immunization factor for women against a teratogenic virus? The questions remain. However, these hypotheses suggest that the buccal microbiota plays an important role.

To understand the effect of a prolonged kiss on this ecosystem, Dutch researchers studied 21 couples. In a study published in Microbiome, they observed that the tongue microbiota was more similar between two partners than between two strangers. Could this be an effect of kisses exchanged by these couples? The truth is not so romantic. This mirroring is more an effect of long-term shared daily habits in terms of food and bodily hygiene. Conversely, the salivary microbiota, which are as distinct within a couple as in any two people on the street, tend to become more similar with more frequent kissing-which leads to 80 million bacteria being exchanged! And although they only colonize the partner’s buccal surfaces temporarily, they are no less important to the constitution of the buccal microbiota, the authors say. Identifying the factors that determine their status (permanent or transitory) may contribute to the development of new preventative or therapeutic strategies for infectious diseases of the mouth.


Remco Kort et al. Shaping the oral microbiota through intimate kissing. Microbiome, 2014, 2:41 http://www.microbiomejournal.com/content/2/1/41