A passionate kiss lasting longer than 10 seconds transfers about 80 million bacteria, Dutch researchers have found. A small sample of 21 couples had the task of French kissing in the name of science. Research evidence Their evidence was recently published in the journal Microbiome.
Study author Remco Kort, from the Netherlands Organisation for Applied Scientific Research (TNO), told HealthDay News, “to our knowledge, the exact effects of intimate kissing on the oral microbiota [microscopic living organisms] have never been studied. 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."
Kort’s team asked the 21 couples a series of questions in order to assess their kissing habits. They inquired how frequently each couples had kissed in the last year, and the last time they had passionately kissed.
The first thing researchers tested was the similarity of the couple’s mouth microbiomes. They found that even before the test kiss, the couples had similar mouth bacteria.
Then, they set out to determine how much bacteria was actually exchanged during a French kiss. One person in each couple drank a probiotic yogurt drink containing a mixture of bacteria. The couples then kissed for 10 seconds. The researchers then took saliva and tongue samples from the kiss receiver (not the one who consumed the yogurt drink).
The saliva and tongue samples were analyzed for signs of the bacteria in the receiver’s mouth. The researchers focused on two types of bacteria, Lactobacillus and Bifidobacteria, which are present at about .15 percent in the mouth.
The bacteria in the receiver’s mouth rose substantially — up to 0.54 percent in saliva and 0.49 percent on the tongue. This led the researchers to their estimation that each kiss carries 80 million bacteria.
"To our surprise, we found that those people that are intimately related ... share much more of that bacteria on their tongue than unrelated individuals," Kort told NPR.
Our mouths are home to more than 700 types of bacteria, but our bodies house so much more than that.