Putting a Sugar Substitute to the Test

By Doug Gillett

For as long as parents have been nagging their children that “too much sugar will make your teeth rot,” kids have been rolling their eyes—and fantasizing about a magical sweetener that would taste great and keep adults off their backs.

That super sugar substitute may already exist. It’s called xylitol, and far from causing cavities, it may actually be able to prevent them. UAB dental researchers led by Sonia Makhija, D.D.S., M.P.H., and principal investigator Gregg Gilbert, D.D.S., are helping to find out as part of the multisite Xylitol for Adult Caries Trial (X-ACT).

Sugar doesn’t actually “eat into” teeth the way many children have been led to believe, says Makhija—cavities are actually caused by oral bacteria. But sugar does create an environment that helps those bacteria attack teeth.

“When you eat sugar, it leads to decay by creating an acidic environment,” Makhija says. “The acidity weakens the enamel on your teeth, which makes them more vulnerable to the bacteria.” But xylitol can’t be converted into acid, she explains, and “that’s why it has some anticariogenic properties—and why we’re looking at it to see if it helps fight cavities.”

A Gleaming Opportunity

Xylitol isn’t exactly a new discovery: It is naturally found in small quantities in many foods, including raspberries and mushrooms. As far back as the 1800s, people in Finland were extracting it from birch trees, and it’s a popular ingredient in chewing gums in both continental Europe and the Far East. Only in 2004, however, did xylitol appear in the formula for Trident gum—advertised as the choice of “four out of five dentists” ever since it was introduced in the 1960s—with the Wrigley Company’s Orbit brand following two years later. And both still employ xylitol only in small amounts.

The X-ACT study aims to provide the most definitive proof yet of xylitol’s cavity-fighting ability. Along with the University of North Carolina at Chapel Hill and the University of Texas Health Science Center at San Antonio, UAB has recruited a total of 750 participants who are being asked to suck on breath mints five times a day for three years. Half of the subjects will get mints containing xylitol, while a control group will get mints sweetened with Splenda, another sugar substitute.

In addition to three years of fresh breath, test subjects in both groups will get oral-health benefits. Sweeteners such as Splenda “increase your saliva and create a more alkaline environment,” says Makhija. “They bathe your teeth in saliva and keep you from having cavities.”

The main question is whether xylitol’s anti-cavity effects might be even greater than those of the artificial sweeteners currently in widespread use. Makhija and her co-investigators finished recruiting subjects this fall, so the final results are still a few years away—but if xylitol does turn out to have dramatic cavity-fighting abilities, she says, it would be a cheap and readily available weapon for consumers and dentists alike in the fight against tooth decay.

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