Pucker Up! Swapping Spit Shares More Than Just Your Feelings For Someone

Brett Smith for redOrbit.com – Your Universe Online
From dessert at a fancy restaurant to a taxi across town, two people in a loving, passionate relationship might share many things and, according to a new study, they also probably share the same community of oral bacteria.
Published in the journal Microbiome, the new study found that up to 80 million bacteria are passed from mouth-to-mouth during a 10-second kiss. The study team also found that romantic partners who kiss each other at least nine times a day have nearly identical oral bacteria communities.
“Intimate kissing involving full tongue contact and saliva exchange appears to be a courtship behavior unique to humans and is common in over 90 percent of known cultures,” noted study author Remco Kort, a cell physiologist at VU University Amsterdam. “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, and it turns out, the more a couple kiss, the more similar they are,” Kort added.
In the study, researchers asked 21 couples to complete surveys on their kissing habits, including their average intimate kiss regularity. The team also acquired swab samples to research the make-up of participants’ oral bacteria community.
The researchers saw that when romantic partners intimately kiss fairly often, their salivary bacteria turn out to be highly comparable. Typically, it was discovered that nine intimate kisses or more per day led to partners having similar salivary communities.
The study team also conducted an experiment to measure the exchange of microorganisms caused by a kiss. In the experiment, one person from each couple drank a probiotic beverage containing distinct varieties of microorganisms; including the benign Lactobacillus and Bifidobacteria bacteria. After a lengthy kiss, the scientists assessed that the amount of probiotic bacteria in the receiver’s mouth tripled, meaning 80 million bacteria overall would have been shifted within a 10 second kiss.
The study also revealed that while tongue bacteria were more similar among partners than unrelated individuals, their likeness did not switch with more common kissing, in comparison to the results for salivary bacteria.
“French kissing is a great example of exposure to a gigantic number of bacteria in a short time,” Kort told BBC News reporter Smitha Mundasad. “But only some bacteria transferred from a kiss seemed to take hold on the tongue.”
As a side note, the study revealed that 74 percent of male respondents reported greater intimate kiss frequencies than a female partner, an average of ten kisses per day reported from the males compared to an average of five per day from their partner.
“Further research should look at the properties of the bacteria and the tongue that contribute to this sticking power,” Kort told Mundasad. “These types of investigations may help us design future bacterial therapies and help people with troublesome bacterial problems.”
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