Scientific Opinion on the substantiation of health claims related to
sugar-free chewing gum sweetened with xylitol and plaque acid
neutralisation (ID 485), maintenance of tooth mineralisation (ID 486, 562,
1181), reduction of dental plaque (ID 485, 3085), and defence against
pathogens in the middle ear (ID 561, 1180) pursuant to Article 13(1) of
Regulation (EC) No 1924/2006[sup]1[/sup]
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2, 3
European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe:
Xylitol
chewing gum
dental plaque
ear
health claims
pathogens
plaque acid
tooth mineralisation
1. Charakterystyka żywności / składnika
The foods/food constituents that are the subject of the health claims are “xylitol-sweetened chewing gum”, “sugar-free chewing gum with xylitol” and “xylitol”. From the information provided, including the conditions of use and the references submitted for the scientific substantiation of the claims, the Panel assumes that the food, which is the subject of the health claim, is sugar-free chewing gum sweetened with xylitol, either alone or in combination with other polyols.
The composition of the gum, i.e. the gum base, is unspecified. The characteristic components of chewing gums are the gum base, which may comprise a complex mixture of elastomers, natural and synthetic resins, fats, emulsifiers, waxes, antioxidants and filler, together with sweetening and flavouring agents (Imfeld, 1999; Rassing, 1996). The common characteristic of sugar-free chewing gums is the absence of fermentable carbohydrates (Edgar, 1998; Ly et al., 2008). The ingredients are well characterised, can be measured by established methods, and the principles of the manufacturing process have been described (Rassing, 1996). Many of the ingredients in the gum base, and most of the sweetening agents used in sugar-free chewing gums, occur naturally in foods.
Xylitol is a well characterised sugar alcohol which occurs naturally in foods. It can be measured by established methods and its manufacturing processes are also well established.
The Panel considers that the food, sugar-free chewing gum sweetened with xylitol, which is the subject of the health claim, is sufficiently characterised in relation to the claimed effects.
2. Znaczenie oświadczenia dla zdrowia człowieka
2.1. Neutralizacja kwasu zawartego w osadzie nazębnym (ID 485)
The claimed effect is “plaque reduction”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to plaque acid neutralisation.
Acid is produced in plaque through the fermentation of carbohydrates by acid-producing bacteria. Lowering plaque pH contributes to demineralisation of tooth tissues.
The Panel considers that plaque acid neutralisation is a beneficial physiological effect.
2.2. Utrzymanie mineralizacji zębów (ID 486, 562, 1181)
The claimed effects are “mouth, teeth” and “tooth remineralisation”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effects refer to the promotion of a beneficial balance between de- and remineralisation of tooth enamel and dentin.
The Panel considers that maintenance of tooth mineralisation is a beneficial physiological effect.
2.3. Redukcja osadu nazębnego (płytki nazębnej) (ID 485, 3085)
The claimed effects are “plaque reduction” and “plaque formation”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to the reduction of dental plaque.
Dental plaque is found on the tooth surface, and consists of a biofilm of microorganisms embedded in a matrix of polymers of host and bacterial origin. Plaque can also become mineralised and form calculus (tartar), a form of hardened dental plaque which provides an ideal medium for further plaque formation. Fermentation of carbohydrates in the mouth by oral bacteria increases the formation of a type of dental plaque that may contribute to dental caries, as well as increase the proportion of cariogenic bacteria in the plaque (Marsh and Nyvad, 2008). Dental plaque can exert adverse effects on dental health (e.g. in relation to approximal caries, gingivitis and periodontitis) when it occurs at sites such as the cervical third, interdentally below the approximal contact point between teeth, along the gingival margin, and in the fissures and pits of the teeth. “Plaque formation” is usually not measured in clinical or in situ studies, but rather the amount of plaque (or “net” plaque formation).
The Panel considers that reduction of dental plaque may be a beneficial physiological effect.
2.4. Ochrona przed patogenami w uchu środkowym (ID 561, 1180)
The claimed effect is “ears”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, clarifications from Member States and references provided, the Panel assumes that the claimed effect refers to defence against pathogens (i.e. Streptococcus pneumoniae) in the middle ear.
The Panel considers that defence against pathogens (i.e. S. pneumoniae) in the middle ear is a beneficial physiological effect.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka
3.1. Neutralizacja kwasu zawartego w osadzie nazębnym (ID 485)
A claim on sugar-free chewing gum and plaque acid neutralisation has already been assessed with a favourable outcome (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA), 2009). The
Panel considers that the scientific substantiation and proposed conditions of use also apply to sugar- free chewing gum sweetened with xylitol.
3.2. Utrzymanie mineralizacji zębów (ID 486, 562, 1181)
A claim on sugar-free chewing gum and maintenance of tooth mineralisation has already been assessed with a favourable outcome (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA), 2009). The Panel considers that the scientific substantiation and proposed conditions of use, also apply to sugar-free chewing gum sweetened with xylitol.
3.3. Redukcja osadu nazębnego (płytki nazębnej) (ID 485, 3085)
A claim on sugar-free chewing gum and reduction of dental plaque has already been assessed with an unfavourable outcome (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA), 2010). The Panel considers that the scientific substantiation of the claim also applies to sugar-free chewing gum sweetened with xylitol. The references cited for this claim did not provide any additional scientific data which could be used to substantiate the claim.
3.4. Ochrona przed patogenami w uchu środkowym (ID 561, 1180)
In one randomised, double-blind, placebo-controlled intervention study the effect of xylitol administered in chewing gum on otitis media and carrier rate of S. pneumoniae was studied in 336 children (mean age 4.9 years) with recurrent acute otitis media (Uhari et al., 1996). Children were randomised to chew two pieces of xylitol chewing gum (8.4 g per day) or sucrose chewing gum (control), five times a day, after meals for two months. The chewing lasted until there was no taste left or for at least five minutes. Nasopharyngeal samples were taken at baseline, at two weeks and at the end of the intervention. Parents were asked to complete a symptom sheet to record the time and reasons for being absent from school, additional xylitol products consumed and medications taken. At any physician’s appointment, physicians were asked to record diagnosis and medications prescribed. The criteria for diagnosis of acute otitis media (AOM) were symptoms and signs of acute respiratory infection, and simultaneous signs of middle ear effusion, cloudy tympanic membrane or impaired tympanic membrane motility in pneumatic otoscopy. As the sample size required to observe a clinically significant effect on S. pneumoniae carrier rate was greater than that required for occurrence of AOM, sample size calculations were based on carrier rates. Considering a carrier rate of 30 % in the study population, 152 subjects per group were needed to reduce the carrier rate to 15 %, with a power of 90 % and a two-tailed p value of 0.05. A total of 30 children dropped out from the study. No reasons for withdrawal were reported. Statistical analyses were performed in the sample of completers (157 in the xylitol chewing gum group and 149 in the control group). No significant differences were observed between groups with respect to the number of upper respiratory tract infections without complications, the duration of any symptom of infection or the pneumococcal carrier rate during the study. The total number of AOM in the xylitol group was 22/157 compared to 43/149 in the control group (relative risk (RR)=0.49, 95 % CI 0.31-0.77). The number of children with at least one episode of AOM was 19/157 (12.1 %) in the xylitol group compared to 31/149 (20.8 %) in the control group (8.7 % difference; 95 % CI 0.4-17 %, p=0.040, relative risk=0.58, 95 % CI 0.34-0.98). The Panel notes that this study shows an effect of xylitol chewing gum use on the incidence of AOM compared to sugar-sweetened chewing gum.
In the randomised, double-blind, placebo-controlled intervention study by Uhari et al. (1998), 857 healthy children were recruited from day care centres, and randomised to one of five intervention groups: control syrup (n=165), xylitol syrup (n=159), control (sugar-sweetened) chewing gum (n=178), xylitol sweetened-chewing gum (n=179) or xylitol lozenges (n=176). The intervention lasted three months and the trial was blinded within the chewing gum and syrup groups. The design, the
protocol for administration of the chewing gums, the daily doses of xylitol, and the diagnosis of AOM were the same as those reported in the study by Uhari et al. (1996). The primary outcome of the study was occurrence of AOM. It was calculated that a total of 150 subjects per group were needed to observe a decrease of 30 % in the occurrence of AOM, with a power of 80 % and a p value of 0.05. A total of 46 children dropped out from the lozenge and the chewing gum groups, twice as many in the lozenge group, but the exact number of drop-outs per group is not reported. Statistical analyses were performed in the sample of completers. The total number of AOM in the xylitol group was 44 (incidence rate 1.04) compared to 72 (incidence rate 1.69) in the control group (difference=0.65, 95 % CI 0.14-1.16, p=0.012). The Panel notes that the RR for the intention-to-treat analysis was 0.61 (95 % CI 0.45-0.84). At least one episode of AOM occurred in 29 children in the xylitol chewing gum group (16 %) and in 39 children receiving the control gum (28 %). The difference was statistically significant (95 % CI 10-71 %; p=0.025). The Panel notes that the RR of having at least one AOM in an intention-to-treat analysis is 0.60 (95 % CI 0.40-0.90). The Panel notes that this study showed an effect of xylitol chewing gum use on the incidence of AOM compared to sugar-sweetened chewing gum.
A recently published systematic review of randomised controlled trials on the use of xylitol in the prevention of AOM in children (Danhauer et al., 2010) identified four publications which met the inclusion criteria (Hautalahti et al., 2007; Tapiainen et al., 2002; Uhari et al., 1996; 1998). All the studies were carried out by the same research group in Oulu (Finland). The authors considered that only the studies by Uhari et al. (1996; 1998) were sufficiently homogeneous to be combined in a meta-analysis. The reasons for not including the studies by Hautalahti et al. (2007) and Tapiainen et al. (2002) in the meta-analysis were that xylitol-sweetened chewing gum was administered at the same doses but only three times daily (Hautalahti et al., 2007), and that xylitol-sweetened chewing gum was administered to children at the onset of an acute respiratory infection (ARI) only (Tapiainen et al., 2002). The Panel considers that the meta-analysis of only two studies, already considered separately in this opinion, does not provide additional information on which further conclusions can be drawn for the scientific substantiation of the claim.
In the randomised, double-blind, placebo-controlled intervention study by Tapiainen et al. (2002), 1,277 healthy children were recruited and randomised to receive either control mixture (n=212), xylitol mixture (n=212), control chewing gum (n=280), xylitol chewing gum (n=286) or xylitol lozenges (n=287) at the onset and during an ARI. The trial was randomised and double blinded within the chewing gum and mixture groups. The design, the protocol for administration of the chewing gums, the daily doses of xylitol, and the diagnosis of AOM were the same as in the study by Uhari et al. (1996). The follow-up lasted until resolution of the infection, or up to three weeks. Sample size calculations were based on the occurrence of ARI and AOM in previous trials. A total of 274 subjects in each group which received the chewing gum were needed to observe a 45 % reduction in AOM, with a power of 80 % and a p value of 0.05. Statistical analyses were performed in the sample of completers (277 in the xylitol chewing gum group and 277 in the control group). A total of 980 subjects (78 %) experienced ARI and visited the study clinic. The proportion of children with ARI was not different between groups. AOM was diagnosed in 24 (8.7 %) of the children in the control chewing gum group and in 31 (11.2 %) of the children in the xylitol chewing gum group (i.e. in 24 (11.0 %) of 218 children and in 31 (14.1 %) of 220 children who had an ARI, in the control and xylitol chewing gum groups, respectively). None of the differences were statistically significant. The Panel notes that this study does not show an effect of xylitol chewing gum use on AOM in children with an ARI compared to sugar-sweetened chewing gum.
In the randomised, double-blind, placebo-controlled intervention study by Hautalahti et al. (2007), 663 healthy children aged 7 months to 7 years were recruited and randomised to receive either control product (n=331), as a sugar sweetened control chewing gum (n=274) or as a control mixture (n=57), or xylitol (n=332), as xylitol chewing gum (n=272) given three times a day after meals (daily dose 9.6 g) or as a xylitol mixture (n=60), for three months. The trial was randomised and double blinded
within the chewing gum and mixture groups, but results are provided only for control and xylitol groups combined. The primary outcome of the study was occurrence of AOM. It was calculated that a total of 244 subjects per group were needed to observe a decrease of 30 % in the occurrence of AOM, with a power of 80 % and a p value of 0.05, assuming that 40 % of children would have at least one episode of AOM in the three months. A total of 38 children (11 %) dropped out in the control group and 58 (17 %) in the intervention group. The most important reason for dropping out was refusal to take the mixture or the gum. At least one episode of AOM occurred in 94 children taking a xylitol product (28 %) and in 98 (30 %) taking a control product, the total number of episodes being 156 and 142, respectively. The incidence rate of AOM per ARI was 2.1 in the xylitol group and 1.8 in the control group. Differences between groups were not statistically significant for any of these variables. The Panel notes that this study does not show an effect of xylitol chewing gum use on the occurrence of AOM in children compared to sugar-sweetened chewing gum.
In weighing the evidence, the Panel took into account that two intervention studies in healthy children showed an effect of xylitol-sweetened chewing gum chewed five times a day on AOM in healthy children (Uhari et al., 1996; 1998), that two additional studies did not show an effect of xylitol- sweetened chewing gum on AOM in children with ARI (Tapiainen et al., 2002), or when consumed three times daily (Hautalahti et al., 2007), and that the evidence provided did not show an effect of xylitol-sweetened chewing gum on S. pneumoniae carrier rate (Uhari et al., 1996). The Panel notes that the results from the intervention studies are inconsistent, and that no evidence of a mechanism by which xylitol-sweetened chewing gum could exert the claimed effect has been provided.
The Panel concludes that the evidence provided is insufficient to establish a cause and effect relationship between the use of sugar-free chewing gum sweetened with xylitol and defence against pathogens (i.e. S. pneumoniae) in the middle ear.
Wnioski
On the basis of the data presented, the Panel concludes that:
The food, sugar-free chewing gum sweetened with xylitol, which is the subject of the health claims, is sufficiently characterised in relation to the claimed effects.
Plaque acid neutralisation (ID 485)
The claimed effect is “plaque reduction”. The target population is assumed to be the general population. Plaque acid neutralisation is a beneficial physiological effect.
A claim on sugar-free chewing gum and plaque acid neutralisation has already been assessed with a favourable outcome. The scientific substantiation and proposed conditions of use also apply to sugar-free chewing gum sweetened with xylitol.
Maintenance of tooth mineralisation (ID 486, 562, 1181)
The claimed effects are “mouth, teeth” and “tooth remineralisation”. The target population is assumed to be the general population. Maintenance of tooth mineralisation is a beneficial physiological effect.
A claim on sugar-free chewing gum and maintenance of tooth mineralisation has already been assessed with a favourable outcome. The scientific substantiation and proposed conditions of use also apply to sugar-free chewing gum sweetened with xylitol.
Reduction of dental plaque (ID 485, 3085)
The claimed effects are “plaque reduction” and “plaque formation”. The target population is assumed to be the general population. Reduction of dental plaque may be a beneficial physiological effect.
A claim on sugar-free chewing gum and reduction of dental plaque has already been assessed with an unfavourable outcome. The scientific substantiation of the claim also applies to sugar-free chewing gum sweetened with xylitol. The references cited for this claim did not provide any additional scientific data which could be used to substantiate the claim.
Defence against pathogens in the middle ear (ID 561, 1180)
The claimed effect is “ears”. The target population is assumed to be the general population. In the context of the proposed wordings, clarifications from Member States and references provided, it is assumed that the claimed effect refers to defence against pathogens (i.e. Streptococcus pneumoniae) in the middle ear. Defence against pathogens (i.e. Streptococcus pneumoniae) in the middle ear is a beneficial physiological effect.
The evidence provided is insufficient to establish a cause and effect relationship between the use of sugar-free chewing gum sweetened with xylitol and defence against pathogens (i.e. Streptococcus pneumoniae) in the middle ear.