Single kiss transfers 80 m bacteria between couples!

A new study has shown that a single intimate kiss can transfer 80 million bacteria between partners.

The research conducted by Netherlands Organisation for Applied Scientific Research on 21 couples, studied responses on the kissing behaviour including average intimate kiss frequency, and then investigated the composition of their oral microbiota on the tongue and in their saliva, the Daily Express reported.

The results showed on an average, lingering kiss at least 9 times a day led to couples having significantly shared salivary microbiota.

According to the experts, the first kiss acted as a "mate-assessment function" and the ones which followed maintain feelings of attachment in long-term relationships.

Lead author Remco Kort, said that the current explanations for the function of intimate kissing, involving full tongue contact and saliva exchange, include an important role for the microbiota present in the oral cavity.

He added that the more a couple kissed, the more similar they were.

In a controlled kissing experiment, a member of each of the couples was given a probiotic drink containing specific varieties of bacteria including Lactobacillus and Bifidobacteria to drink, and after an intimate kiss, it was found that the quantity of probiotic bacteria in the receiver's saliva rose threefold.

They calculated that in total 80 million bacteria would have been transferred during a 10 second kiss.

The study is published in the journal Microbiome.