Your Ethnicity Could Determine The Bacteria In Your Mouth: Genetic Makeup 'Influences Microbial Community'

oral bacteria
Oral bacteria was unique to each participants ethnicity, researchers found. SuperFantastic, CC BY 2.0

Fingerprints are one of, if not the only things unique to each and every individual. For this reason, it makes it easy to pinpoint who belongs to each fingerprint. It turns out that the bacteria in our mouths is almost as unique, and has many similarities to other oral bacteria among people in the same ethnic groups, according to a new study.  

There were 398 different species of bacteria living underneath the gums of 100 participants representing the four major ethnic groups living in the United States — non-Hispanic blacks, non-Hispanic whites, Chinese, Latinos. With the help of DNA-sequencing, the researchers found that only two percent of the species were found living — in different concentrations — within every participant’s mouth. Eight percent of the same bacterial species were found in 90 percent of their mouths.

“This is the first time it has been shown that ethnicity is a huge component in determining what you carry in your mouth,” study author Purnima Kumar, associate professor of periodontology at The Ohio State University, said in a statement. “We know that our food and oral hygiene habits determine what bacteria can survive and thrive in our mouths, which is why your dentist stresses brushing and flossing. Can your genetic makeup play a similar role? The answer seems to be yes, it can.”

The researchers then programmed an algorithm into a machine that would be able to classify the DNA signatures of each bacteria. The machine was able to predict overall ethnicity with 62 percent accuracy. Breaking it down into specific ethnicities, the machine linked blacks, Latinos, and whites to their particular bacterial communities 100 percent, 67 percent, and 50 percent of the time, respectively.

“This is interesting because although African Americans and Caucasians have shared similar environmental factors including food, nutrition, and lifestyle over several generations — unlike Chinese and Latino subjects who were either immigrants or first generation residents — they demonstrated distinct microbial communities,” the researchers wrote. This suggests that the individual’s genetic makeup “influences the microbial community to a greater extent than shared environment; ‘nature’ appears to win over ‘nurture’ in shaping this community.”  

These differing communities could put certain ethnicities at risk for different kinds of oral disease. Conversely, they could offer paths for personalized oral care, the researchers wrote. These bacterial communities interact with the immune system, Kumar said, and the key to overall health is to maintain good health in the communities.

Oral diseases, such as gingivitis and periodontitis, are caused by poor oral hygiene and the growth of bacteria, which leads to plaque and tartar buildup — these form a protective shield for bacteria. Some studies have shown that poor oral health can lead to other diseases. For example, one study found that oral bacteria normally associated with gum disease was found in colorectal tumors. Another one found bacteria associated with gingivitis in the brains of people with Alzheimer’s disease.  Preventing any of these risks is simple though: Brush twice daily — or after each meal — and floss at least once a day.  

Source: Mason M, Nagaraja H, Kumar P, et al. Deep Sequencing Identifies Ethnicity-Specific Bacterial Signatures in the Oral Microbiome. PLOS One. 2013. 

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