Diabetes Forecast

Your Mouth Offers Clues to Heart Health

Anwar Merchant looks for links between dental plaque and cardiovascular risk

Anwar Merchant, ScD, MPH, DMD

Photograph by Jeff Amberg

Anwar Merchant, ScD, MPH, DMD

Occupation: Epidemiologist
Focus: Diabetes and Oral Health
ADA Research Funding: Clinical Translational Award

No matter how conscientiously you brush, you’re never alone: Your mouth is a complex, lively world of its own, containing more than 500 different species of microorganisms, some of them not yet named.

Some of these microscopic organisms are helpful. Bacteria in the mouth help the gums and teeth stay healthy, for example. Others are harmful. Researchers have long known that gum disease, cavities, root canal infections, and tonsillitis are caused by oral bacteria. And in recent years, scientists have begun to trace the way the mouth’s microorganisms affect the rest of the body. Oral bacteria have been connected to everything from stroke and preterm births to pneumonia and diabetes.

As we learn more about the complex world inside our mouths, known to researchers as the “microbiome,” some scientists are hoping to discover how specific populations of microorganisms relate to health problems. One target is cardiovascular disease. People with diabetes are at particular risk for heart trouble: The American Diabetes Association estimates that people with diabetes are twice as likely to have a heart attack or stroke as people without. They’re also more likely to have periodontal disease, which affects your gums and teeth.

With the help of a grant from the ADA, University of South Carolina researcher Anwar Merchant is working to see if it’s possible to tell from the plaque on your teeth if you might be at higher risk for heart disease. Merchant’s work is part of an ongoing study in Colorado comparing children with diabetes and children without. The kids with diabetes who were tested were typically between 10 and 12 years old, and had lived with diabetes for at least five years.

Merchant and his collaborators took samples of mouth plaque, the stuff that builds up on your teeth if you don’t brush and floss regularly. “We got samples of their plaque and analyzed for 41 microorganisms known to be associated with periodontal disease,” Merchant says. “These organisms are found in everyone’s mouth. Everyone has them. But some are found in larger numbers than others.”

 At the same time, they measured standard indicators of heart disease. They found that kids with a certain profile—more of certain species of microorganisms, for example—also had early risk factors for heart disease, such as high blood pressure and abnormal cholesterol.

“We classified the microbiological profile of the kids based on the organisms we got from their mouths,” Merchant says. “We’re relating the profile with the outcomes. Are the profiles the same or different between people with or without diabetes? Do people with a certain microbial profile have higher or lower markers of cardiovascular disease?”

Merchant’s early results suggest that there are clear connections between the state of your mouth and the health of your heart. What’s still unknown is why. Do the microorganisms help cause cardiovascular disease, or is there some other, as yet undiscovered, connection between the mouth and the heart?

One mechanism Merchant and others think might be at work is inflammation, starting with irritated gums and then affecting other parts of the body. “It’s possible that these organisms cause inflammation in the mouth and in the body that can impact various systems including the heart and … insulin action,” he says. “People with diabetes are more prone to get cardiovascular disease. This might be one more thing that adds to it.”

Another possibility is that the millions of microorganisms living in your mouth might actually be on the move, entering your bloodstream through tiny cuts in your gums. Researchers have found colonies of a particularly nasty bug called Porphyromonas gingivalis, the bacterium that helps cause the gum disease gingivitis, along the walls of clogged-up blood vessels that supply the heart.

Merchant hopes his research will help create clear connections between the type of bacteria in your mouth and your risk of heart disease. That might allow doctors to identify people at higher risk for heart disease by simply sampling the bacteria in their mouths. “If there is an association, then eventually the microbiome might dictate treatment in the future,” Merchant says.

In the long run, it might be possible to come up with a treatment that can protect or heal the heart by changing the balance of your mouth’s microbiome. But until then, Merchant encourages people to brush, floss, and visit the dentist regularly. Given the links between diabetes and heart disease, he says, “this might be one more reason for people with diabetes to visit the dentist.”

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