At first glance, a claim that a sweetener derived from the bark of birch trees can prevent cavity formation might seem farfetched. It can’t be true, some might reason. Sugar causes cavities.
Not only are they wrong: The sweet compound from birch trees called xylitol does ward off cavities. But they are wrong twice, as it does so by blocking acid-producing bacteria in the mouth – the real cause of cavities, not sugar.
For an installment in our Fad or Fact? series, we spoke with Casey Rhines, DDS, clinical assistant professor in the Department of Restorative Dentistry at the University of Colorado Anschutz School of Dental Medicine, to learn more about the buzz around xylitol, a sugar alcohol found in a growing number of products, including toothpastes, gummy bears, mouthwashes and mints.
The takeaway:
Xylitol is a sugar alcohol that may help prevent cavities because oral bacteria cannot ferment it into acid. Since acid – not sugar itself – is the direct cause of tooth decay, xylitol can reduce cavity risk by limiting acid production and lowering levels of cavity-causing bacteria such as Streptococcus mutans. Dentists may recommend xylitol-containing products as part of a broader cavity-prevention strategy.