New research from Cornell University suggests that brushing after eating starchy foods may be more important for some people than others.
A study published Feb. 19 in Microorganisms found that the number of copies of a specific gene, AMY1, influences how bacteria in the mouth respond to starch. The findings help explain why some people develop cavities and gum disease despite good oral hygiene.
“Most people have been warned that if you eat a bunch of sugar, make sure you brush your teeth,” said senior author Angela Poole, an assistant professor of molecular nutrition at Cornell University. “The takeaway here is that depending on your AMY1 copy number, you may want to be just as vigilant about brushing your teeth after eating digestible starches.”
“If someone has a high copy number, they break down starch efficiently, and bacteria that like those sugars are going to grow more in that person’s mouth.”
An advantage with a tradeoff
The study, funded by the Schwartz Research Fund and the U.S. National Institutes of Health, analyzed saliva samples from 31 participants aged 19 to 57 with varying AMY1 copy numbers. Researchers found that those with more copies of the gene break down starch more efficiently, but this advantage may come with a tradeoff—higher populations of bacteria, such as Streptococcus, that thrive on starch-derived sugars.
“If someone has a high copy number, they break down starch efficiently, and bacteria that like those sugars are going to grow more in that person’s mouth,” Poole said. “So, you can have species behave differently based on the different substrates. It’s pretty incredible—how we adapt and these microbes turn around and adapt, too.”
The study concluded that researchers now have evidence of the “important interplay” between diet, genetics, and oral microbiota, providing new insights into the impact of evolution on oral health.
Co-authors of the study include first author Dorothy Superdock, Lynn M. Johnson, doctoral student Megan Eno, former lab manager Jennifer Ren, and researchers Alizeh Khan and Shuai Man.
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