Practicing good hygiene won’t disrupt oral microbiome

Dear Doctor: Our dad is a science geek, and his new obsession is the gut microbiome. But now he’s telling anyone who will listen that the mouth microbiome is just as important as the one in the gut. Is that really true? Am I helping or hurting it when I brush my teeth?

Dear Reader: Kudos to your scienceminded father, who is clearly staying current on the latest research. The oral microbiome, which according to most scientists includes the mouth and the associated nasal regions and cavities, turns out to be second in size only to the microbiome in our guts. It’s home to more than 700 different bacterial species, as well as viruses, fungi and protozoa. That means it’s one of the most densely populated anatomical sites in our bodies.

Studies have shown that different areas of the mouth and its associated areas, including the pharynx, esophagus, trachea, nasal passages, Eustachian tubes, middle ear and sinuses – are colonized by microbial communities that are unique from one another. And thanks to stable temperature and moisture, a consistent food supply, and a pH range of 6.5 to 7.5, which hits the bacterial sweet spot, the oral-nasal cavity is the ideal bacterial environment.

Not only do these conditions allow the many millions (some say it’s billions) of bacteria in the oral microbiome to thrive, the location itself means they are uniquely mobile. Thanks to saliva production and the vascular systems that keep our gums, tissues and nasal membranes healthy, bacteria from our mouths and noses wind up in the GI tract and in the bloodstream. The passage of air through the nose and mouth carries bacteria to the trachea and lungs. That places the various components of the oral microbiome into prime position to travel throughout the body. Not only are residents of the oral microbiome known to be responsible for conditions like morning breath, plaque and gum disease, researchers have established connections between oral bacteria and a variety of cardio issues.

New research is now focused on exploring potential connections to outcomes as diverse as pregnancy complications, diabetes, respiratory diseases, various cancers and even certain neurological conditions like Parkinson’s disease and multiple sclerosis.

In answer to your second question, no, you’re not killing your oral microbiome when you brush your teeth. Please, don’t stop brushing. And do continue flossing. Use a good toothbrush and practice proper technique. If you think that maybe you’re doing either one wrong, your dentist will be happy to guide you.

Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.

Send your questions to askthedoctors@mednet.ucla.edu.