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Microbiome Candy: Could A Probiotic Mint Help Prevent Cavities?

A sweet way to avoid the dentist? Microbiologists are developing a probiotic mint that uses dead bacteria to fight off cavities.
Morgan Walker
A sweet way to avoid the dentist? Microbiologists are developing a probiotic mint that uses dead bacteria to fight off cavities.

Eat candy and fight tooth decay. What a sweet concept, right?

Well, microbiologists in Berlin are trying to make that dream a reality.

They've created a sugarless mint that's aimed at washing out cavity-causing bacteria from your mouth. And the candy works in a curious way: It's spiked with dead bacteria. It's like probiotics for your teeth.

The experimental mint is still in the early days of development — and far from reaching the shelves at Walgreens.

But a study involving a few dozen volunteers published in September suggests that the concept is promising: Sucking on the bacteria-laced mints lowered the levels of cavity-causing bacteria in the saliva of volunteers, microbiologists reported in Probiotics and Antimicrobial Proteins.

So how does the candy work?

Our mouths are microbial jungles. They're filled with more than 600 species of bacteria. Most of them are harmless. But in terms of tooth decay, one critter is the major culprit: Streptococcus mutans. These bacteria take sugars in our food and turn them into tooth-dissolving acids.

So microbiologist Christine Lang at Organobalance — a German research and development firm that focuses on probiotics — thought, why not get the good bacteria to fight off the bad ones?

"We were looking for something new for oral hygiene," Lang tells The Salt. "Something that specifically recognizes and binds to Streptoccocus mutans, but wouldn't kill the other microbes in the mouth."

Lang and her team screened nearly 800 different types of bacteria until they found one critter that keeps Streptoccocus from sticking onto the surface of teeth. The healthy bacteria, called Lactobacillus paracasei, are found in yogurt and kefir, and they seem to stop Streptoccocus even when they're dead. (That's because the good bacteria hook onto Streptoccocus and cause it to clump up, Lang says.)

So the researchers spiked a sugarless mint with the dead Lactobacillus and then had people suck on the candies. Ten minutes later, the researchers measured the levels of the bad bacteria in the volunteers' mouths. They found that the dead bacteria did strip away some of the Streptoccocus in the volunteers' saliva. However, the effect was small and researchers don't know yet how long it lasts.

Even so, the results are encouraging enough, Lang says, that her team is planning a larger and longer experiment. But James Bader at the University of North Carolina School of Dentistry is more skeptical.

"The concept is sound," the research dentist tells The Salt. "Anything we can do to reduce the concentrations of strep mutans in the mouth is good."

But it's way too early to draw many conclusions, he says. "The reduction by the candy is really temporary and very small," he says.

To fight cavities, Bader says, the candy would have to go after bacteria stuck in the plaque on the teeth — not bacteria in the saliva. "What the researchers have shown is that it [sucking on the candy] has some activity in deactivating Streptococcus mutans that are free-floating in the mouth," he says. "They still have to prove that it reduces the bacteria in the biofilm on the teeth."

And that can be a trickier task, Bader says. For decades, he notes, dentists thought that a chemical put in sugarless candy and gum, called xylitol, reduced cavities by killing Streptococcus inside the plaque.

But a large, long-term study by Bader and his colleagues this year didn't support the claims. Even sucking on xylitol lozenges five times a day for three years didn't significantly cut a person's risk for developing cavities, the study found.

"Gum manufacturers have taken a long look at the effect of sugarless gum on teeth" Bader says. "People have less plaque [when they regularly chew gum], but the companies haven't shown that they have less caries."

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Michaeleen Doucleff, PhD, is a correspondent for NPR's Science Desk. For nearly a decade, she has been reporting for the radio and the web for NPR's global health outlet, Goats and Soda. Doucleff focuses on disease outbreaks, cross-cultural parenting, and women and children's health.
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