The sweetest and most passionate kiss could turn into a fatal kiss of death, depending on what kind of microbes you share and transfer in the process. And it only takes 10 seconds of locking each other's lips for the microbes to be transferred from one to the other. There could be as many as 80 million bacteria to be shared with kissing, a new study says..
Researchers from the Netherlands Organization for Applied Scientific Research (TNO) interviewed 21 couples, and asked them to fill out questionnaires about their past kissing habits, including the frequency of their French kisses.
They monitored the kissing behaviour of the couples and found those who kissed nine times a day were most likely to share salivary microbes.
Scientists took bacterial samples from the volunteers' tongues and saliva before and after a strictly timed 10-second kiss. They swabbed their tongues and saliva to look at the composition of the oral microbiota, which are the microorganisms that live in the mouth. Studies suggest the mouth is home to more than 700 different types of bacteria - but the report reveals some are exchanged more easily than others.
For the controlled part of the experiment, one member of the couple had drunk a probiotic drink containing a specific bacteria before kissing his or her partner.
Researchers calculated that 80 million bacteria were transferred during a 10-second kiss.They also found that couples who kissed at least nine times a day were more likely to share similar communities of oral bacteria.
"Intimate kissing involving full tongue contact, and saliva exchange appears to be a courtship behavior unique to humans and is common in over 90% of known cultures," lead author Remco Kort said in a release. "We wanted to find out the extent to which partners share their oral microbiota, and it turns out, the more a couple kiss, the more similar they are."
"French kissing is a great example of exposure to a gigantic number of bacteria in a short time. But only some bacteria transferred from a kiss seemed to take hold on the tongue," Kort added. "Further research should look at the properties of the bacteria and the tongue that contribute to this sticking power, as these types of investigations may help us design future bacterial therapies and help people with troublesome bacterial problems."
The study was published in the journal Microbiome.
