A new study has revealed that people who kiss, on average, more than nine times per day have similar bacteria living inside their mouths.
Our organism is home for more than 100 trillion microorganisms – the microbiome – which are essential to the digestive system, nutrient synthesizing and disease prevention. Although the microbiome is mainly shaped by age, genetics and diet, the people with whom we interact are also important. Given the fact that our mouth alone hosts over 700 varieties of bacteria it is no surprise that the people closest to us can influence our oral microbiata.
Also, the study showed that people who engage in the sensual interaction at relatively high frequencies are more likely to have similar salivary microbiata.
In order for the study to be carried out, the researchers from Micropia and TNO in the Netherlands tested 21 couples who were asked about their kissing behavior. Afterwards, each of the individuals was given a specific kind of probiotic drink, which contained certain traceable varieties of bacteria.
The couples where then asked to engage in an intimate kiss, in the name of science. A series of calculations were made and the result was that nearly 80 million bacteria were transferred during a 10 seconds-long kiss.
While looking at the results concerning salivary microbiata, the scientists tested the tongue microbiata as well. Even though tongue microbiata was more similar among people who shared different dietary or sanitary habits than among unrelated individuals, the frequency of kissing did not affect the overall bacterial population.
Remco Kort , the lead author from TNO’s Microbiology and Systems Biology department noted in a press release:
“Interestingly, the current explanations for the function of intimate kissing in humans include an important role for the microbiota present in the oral cavity, although to our knowledge, the exact effects of intimate kissing on the oral microbiota have never been studied. We wanted to find out the extent to which partners share their oral microbiota.”
In order for the scientists to be able to calculate the number of bacteria transferred in a kiss, they used average transfer values and a several assumptions related to bacterial transfer, the kiss contact surface, and the average value of saliva volume.