Doubt was cast on the natural sweetener’s anti-caries effect last year when a Cochraine review declared there was little evidence. The review included data from over 5,900 subjects using xylitol-based lozenges, sweets, toothpastes, syrups, and tooth-wipes.
However, using an in vitro dental simulator with artificial saliva, DuPont believes it has proven that xylitol is protective against tooth decay because it lowered gram-positive bacteria Streptococcus mutans (S. mutans) – a known cause of cavities.
The findings add more weight to the EFSA-backed argument that chewing xylitol gum prevents cavities, it says.
“This in vitro study was the first to test the effect of xylitol on S. mutans using our in-house dental simulator,” said Krista Salli, scientist at DuPont Nutrition & Health in Kantvik, Finland.
“It is encouraging to see that the results closely reflect clinical findings,” she added. “This will help us understand the mechanism by which xylitol exerts in benefits.”
Other health organisations already backing xylitol anti-caries claims includes the UK's National Health Service (NHS) which says it helps neutralise plaque acidity on teeth.
The DuPont study
The study looked at the effects of xylitol and sucrose on three strains of S. mutans and one strain of Streptococcus sobrinus in a dental simulator.
The simulator mimicked the oral cavity environment through a continuous-flow system of artificial saliva, keeping a constant temperature and mixing. It had a hydroxyapatite surface – the calcium apatite found in teeth and bones – where the effects of xylitol and sugar were observed.
The team found the xylitol decreased most of the bacteria in the simulator compared to untreated saliva, with the exception of the S. mutans isolate 117.
As expected, sucrose alone increased bacterial colonisation on the hydroxyapatite.
However, when xylitol of 2 to 5% concentration was added into the simulator a decrease in harmful bacteria was observed, even when sugar was present.
“The results indicate that xylitol affects the ability of certain S. mutans strains to adhere to the hydroxyapatite,” the team wrote in Archives of Oral Biology.
“Clinical studies have also shown that xylitol consumption decreases caries incidence and reduces the amount of plaque. This study contributes to the understanding of the mechanism behind these clinical observations.”
Another recent study compared xylitol’s anti-caries properties with those of fellow natural sweetener, stevia. Xylitol in 5% concentration resulted in significantly less plaque than 5% stevia, though at 0.5% concentration there was little difference between the two.
Source: Archives of Oral Biology
Published online: October 2016, vol. 70, pp 39–46, doi: http://dx.doi.org/10.1016/j.archoralbio.2016.05.020
“Influence of sucrose and xylitol on an early Streptococcus mutans biofilm in a dental simulator”
Authors: Krista Salli et al.