The review looked at data from 10 studies involving over 5,903 subjects and lozenges, sweets, toothpastes, syrups, and tooth-wipes containing xylitol.
Lead researcher, Philip Riley of the University of Manchester said: “The evidence we identified did not allow us to make any robust conclusions about the effects of xylitol, and we were unable to prove any benefit in the natural sweetener for preventing tooth decay.”
Limited evidence for toothpaste
The report said: “We found some low quality evidence to suggest that fluoride toothpaste containing xylitol may be more effective than fluoride-only toothpaste for preventing caries in the permanent teeth of children, and that there are no associated adverse effects from such toothpastes."
However it says this evidence should be approached with caution because of a high risk of bias - both studies were conducted by the same authors and with the same subjects. It may therefore only be relevant to the population studies, say the researchers.
“The remaining evidence [for other xylitol-containing products] is of low to very low quality and is insufficient to determine whether [they] can prevent caries in infants, older children, or adults,” it added.
‘Surprising’ results counter EFSA-backed claim
In 2008 EFSA accepted a health claim for chewing gum containing xylitol, allowing manufacturers to claim “Xylitol chewing gum reduces the risk of caries in children”. However, it rejected the same claim for lozenges because of “significant weaknesses” in the research presented to prove the claimed effect.
The claim was authorized for 2-3 g of the gum consumed at least three times a day after meals 'as part of a balanced diet'.
The Cochrane researchers said they were ‘particularly surprised’ to see such a lack of evidence on xylitol-containing chewing gums.
They said the sweetener is thought to help prevent tooth decay – which affects up to 90% of children and most adults worldwide – by increasing saliva and reducing the growth of bad bacteria and acid production in the mouth.
Source: The Cochrane Library
Published Online 26 March 2015, doi: 10.1002/14651858.CD010743.pub2.
“Xylitol-containing products for preventing dental caries in children and adults”
Authors: Riley P, Moore D, et al