Following an application from Wrigley GmbH submitted pursuant to Article 14 of Regulation (EC) No 1924/2006 via the Competent Authority of United Kingdom, the Panel on Dietetic Products, Nutrition and Allergies was asked to deliver an opinion on the scientific substantiation of a health claim related to sugar-free chewing gum and maintenance of tooth mineralisation which reduces the risk of dental caries.
The scope of the application was proposed to fall under a health claim referring to disease risk reduction.
The food, which is the subject of the health claim, is sugar-free chewing gum containing both bulk sweeteners (typically xylitol, sorbitol and mannitol) and high intensity sweeteners that are authorised for use in the EU. Typical proportions used for manufacturing sugar-free chewing gum are described by the applicant. The ingredients are well characterised and can be measured by established methods. The Panel considers that the food, sugar-free chewing gum, which is the subject of the health claim, is sufficiently characterised.
The claimed effect is “sugar-free chewing gum maintains tooth mineralisation which reduces the risk of dental caries”. The target population is the general population. The Panel considers that reducing tooth demineralisation might be a beneficial physiological effect in the context of reducing the risk of caries.
The applicant identified a total of 37 publications, which included 21 human intervention studies, one human observational study, one meta-analysis, one systematic review, eight other review publications, and five guidelines/consensus opinions. Eight in situ studies investigated the effect of chewing sugar free gums on net remineralisation of tooth tissues with lesions rather than on net demineralisation of enamel. The Panel considered that no conclusions could be drawn from these studies for the substantiation of the claimed effect.
One meta-analysis comprised 19 articles including six randomised controlled trials, nine controlled clinical trials and four cohort studies which investigated the efficacy of interventions using sugar-free chewing gums compared to no gum chewing. The studies lasted 24 to 40 months; the populations were all school aged children, representing different socio-economic status and countries. The polyols used were xylitol, xylitol-sorbitol blend, sorbitol and sorbitol-mannitol blend. The most common outcome was development of caries lesions. The outcome used in the meta-analysis was prevented fraction (PF). Pooled results revealed a PF of 58 % for the xylitol-containing gum, 52 % for the xylitol/sorbitol-containing gum, and 20 % for the sorbitol-containing gum. In addition, two out of three studies using a sorbitol-mannitol gum showed a reduction in the incidence of caries lesions. One study included in the meta-analysis used a xylitol gum, a sorbitol gum and a control gum without bulk sweeteners in a three year intervention. The study found that caries increments were significantly lower for all three gums, including the control gum, compared to the no gum group; indicating that a caries reduction occurs regardless of the presence of bulk sweetener in the sugar-free gum.
A systematic review included eight trials on the effects of using sugar-free gum with sorbitol, with xylitol, and with a combination of sorbitol/xylitol. The use of chewing gum varied in frequency per day and duration. Seven out of eight studies demonstrated significant caries reduction. Caries reduction appeared to be independent of polyol type, polyol composition and concentration and chewing regimes.
The de- and remineralisation equilibrium of teeth is mainly driven by saliva and the main contributors are flow rate and concentrations of calcium, phosphate, and bicarbonate. At rest, low amounts of saliva are secreted, but stimulation by chewing may increase saliva flow more than 10-fold. When flow rate increases, saliva concentration of calcium, phosphate and bicarbonate also increases, and such increases favour remineralisation of tooth crystals.
In weighing the evidence, the Panel took into account that almost all of the clinical trials of sugar-free chewing gum consumption showed reduced tooth demineralisation as indicated by a reduction in caries incidence, and that there was strong evidence supporting the biological plausibility for the effect.
The Panel concludes that a cause and effect relationship has been established between the consumption of sugar-free chewing gum and reduction of tooth demineralisation and a reduction in incidence of caries. Tooth demineralisation may contribute to increased risk of caries.
The Panel considers that, in order to obtain the claimed effect, 2-3 g of sugar-free chewing gum should be chewed for 20 minutes at least three times per day after meals. This quantity and pattern of use of chewing gum can easily be included within a balanced diet.
There is a risk of osmotic diarrhoea at excessive intakes of polyols. The use of chewing gum should be avoided in children less than three years of age owing to a high choking hazard of chewing gum in this age group.