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article imageStudy: A 10-second kiss could transfer 80 million bacteria

By JohnThomas Didymus     Nov 17, 2014 in Health
Amsterdam - According to a new study, kissing for only 10 seconds could transfer up to 80 million bacteria. However gross that might sound, scientists believe that sharing bacteria through kissing helps us stay healthy by boosting the immune system.
Dutch researchers from the Netherlands Organization for Applied Scientific Research (TNO) and Micropia asked 21 couples, including two gay couples, visiting the Artis Royal Zoo in Amsterdam, to fill out a questionnaire requiring information about their recent past kissing behavior, such as how many times the couples have kissed daily over the past year and how long ago they last shared an intimate kiss.
The researchers then asked the couples for permission to have their mouths and tongues swabbed before and after a strictly timed 10-second kiss. They used the swab to determine the bacterial population on the tongue and in the saliva before and after kissing.
One of the couples was asked to drink a probiotic yoghurt containing specific types of known bacteria, including Lactobacillus and Bifidobacterium. After taking the yogurt, the couples were allowed to kiss again and a second swab taken.
The scientists found through examination of the swab that the population of probiotic bacteria in the saliva of the partner who did not drink the probiotic yogurt increased threefold. They were able to estimate that a 10-second intimate kiss could transfer up to 80 million oral microbes.
The study, published in the journal Microbiome, found that couples who regularly shared nine or more intimate kisses daily had very similar oral bacteria. But the study also found that although kissing changed the population and types of bacteria in the saliva more readily, couples tended to share a more stable and similar population of tongue bacteria than salivary bacteria.
According to Remco Kort of TNO who led the study, "bacteria find a niche" in the tongue, "and they colonize there over longer periods of time... [but] the saliva is a very dynamic environment. In this, we could see the direct effect of a kiss, but it disappears over time."
He added: "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."
The study concluded that kissing helps couples build a similar population of oral bacteria. This could help couples develop immunity against bacterial infections they might transmit to each other.
Kort said: "Intimate kissing involving full tongue contact and saliva exchange appears to be courtship behavior unique to humans and is common in over 90 per cent of known cultures."
It is estimated that the human body carries about 100 trillion microbial organisms. Previous studies have shown that the mouth alone is home to more than 700 different types of bacteria. The population of bacteria an individual carries in and on his body constitutes a microbiota or microbiome.
The human microbiome plays a vital role in maintaining the normal functions of physical health such as digestion, nutrient synthesis, maintenance of healthy skin condition, and preventing colonization of the body by potentially harmful bacteria.
The microbiome ecosystem unique to an individual is influenced by genetic inheritance, health, age, diet, lifestyle and the people the individual comes in contact with in daily life.
Although 80 million might sound like a huge number of microbes to share in 10 seconds of kissing, it is really a very small number when compared with the total of about 100 trillion microbes we carry about on and in our bodies.
The possible benefit of exposure to a wider variety of microbes through kissing is highlighted by recent warnings from experts that the increasing emphasis on hygiene as a way of avoiding infectious diseases has negative health consequences. According to experts, raising children under excessively hygienic conditions prevents the immune system from receiving the boost it needs to develop the ability to resist a variety of infections routinely encountered in the environment.
Immune systems that have not been sufficiently primed are more prone to allergic reactions such as asthma and other health complications. Experts have suggested that the increasing incidence of allergies could be due to the fact that people are less exposed early in life to a variety of germs that help to build the body's ability to defend itself against infections.
According to Kort, "There are a number of studies that show if the diversity in bacteria increases this is a good thing. If you look at it from this point of view, kissing is very healthy."
The study was conducted by TNO scientists in collaboration with Amsterdam's Micropia, the world's first museum of microbes. Micropia has opened an exhibition where couples may share a kiss and take a test using the interactive "Kiss-o-meter" to measure the duration and intimacy of the kiss. The information is used to estimate instantly the number of microbes the couple likely transferred.
More about 80 million bacteria, 10second kiss, microbiome, Microbiota, Immune System
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