Scientific Opinion on the substantiation of health claims related to
sugar-free chewing gum and dental and oral health, including gum and
tooth protection and strength (ID 1149), plaque acid neutralisation
(ID 1150), maintenance of tooth mineralisation (ID 1151), reduction of oral
dryness (ID 1240), and maintenance of the normal body weight (ID 1152)
pursuant to Article 13(1) of Regulation (EC) No 1924/2006[sup]1[/sup]
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2
European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe:
Sugar-free chewing gum
body weight
chewing gum
dental health
dental plaque
health claims
oral dryness
oral health
plaque acid neutralisation
saliva
tooth mineralisation
1. Charakterystyka żywności / składnika
The food that is the subject of the health claim is sugar-free chewing gum. The composition of the gum, i.e. gum base and sweetening agent, 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, and the sweetening and flavouring agents (Rømer Rassing, 1996; Imfeld, 1999). 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 (Rømer Rassing, 1996). Many ingredients in the gum base and most sweetening agents used in sugar-free chewing gums occur naturally in foods.
Gums with specific active ingredients, such as urea, carbamide or fluoride, are not included in this evaluation.
The Panel considers that the food, sugar-free chewing gum, which is the subject of the health claims, is sufficiently characterised in relation to the claimed effects.
2. Znaczenie oświadczenia dla zdrowia człowieka
2.1. Zdrowie jamy ustnej, w tym ochrona i wytrzymałość dziąseł i zębów (ID 1149)
The claimed effects are “dental health”, “oral health” and “gum and tooth protection and strength”. The Panel assumes that the target population is the general population.
The claimed effects are general and non-specific and the proposed wordings (“beneficial to dental health”, “safe for teeth”, “promotes healthy teeth and gums”, “helps protect teeth and gums”, “helps to strengthen teeth and gums”) do not identify any specific health claim as required by Regulation (EC) No 1924/2006.
The Panel considers that the claimed effects are general and non-specific and do not refer to any specific health claim as required by Regulation (EC) No 1924/2006.
2.2. Neutralizacja kwasu w osadzie nazębnym (ID 1150)
The claimed effect is “to support plaque acid neutralisation”. The Panel assumes that the target population is the general population.
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 beneficial to human health.
2.3. Utrzymanie mineralizacji zębów (ID 1151)
The claimed effect is “supporting localised tooth mineralisation”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel notes that the claimed effect refers to the promotion of a beneficial balance between de- and remineralisation of tooth enamel and dentin.
The Panel considers that maintaining tooth mineralisation is beneficial to human health.
2.4. Zmniejszenie suchości w jamie ustnej (ID 1240)
The claimed effect is “reduces/improves dry mouth”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel notes that the claimed effect relates to the relief of symptoms owing to a lowered saliva secretion or inadequate moistening or lubrication of oral tissues. A dry mouth may lead to oral discomfort and to difficulties in swallowing and speaking.
The Panel considers that reducing oral dryness is beneficial to human health.
2.5. Osiąganie lub utrzymywanie prawidłowej masy ciała (ID 1152)
The claimed effect is “weight management”. The Panel assumes that the target population is the general population.
Weight management can be interpreted as the contribution to the maintenance of a normal body weight. In this context even a moderate weight loss in overweight subjects without achieving a normal body weight is considered beneficial to health.
The Panel considers that the maintenance or achievement of a normal body weight is beneficial to human health.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka -
Chewing and taste confer physiologic stimulation to the secretory cells of the salivary glands via autonomic nerve signalling (Anderson et al., 1998; Wong, 2008). At rest, low amounts of saliva are secreted (mean 0.2 ml/min), but chewing and taste stimulation may increase saliva flow more than 10 fold. Elevated secretion is maintained even after extended stimulation. The main component of saliva is water, with rinsing and dilution effects. Saliva also contains an array of other components (e.g. minerals, mucins and other proteins and peptides) with relevant biological functions, such as buffering of acids, bacteria regulatory effects, lubrication, or crystal formation (Screebny, 2000; Wong, 2008). The relationship between flow rate and concentrations of various saliva components varies. As flow rate increases, the concentration of calcium and bicarbonate in saliva increases, whereas the concentration of many proteins decreases significantly (Anderson et al., 1998; Wong, 2008).
Salivary factors of possible relevance for “oral health” differ between tissues. For the hard tissues (i.e., enamel, dentin), rinsing of debris, dilution, de- and remineralisation, pH neutralisation, and regulation of the bacterial community on the teeth are relevant, whereas flushing and innate immunity proteins and peptides, among others, are relevant for soft tissues (Screebny, 2000; Wong, 2008).
Tooth hydroxyapatite crystals are very resistant to dissolution at neutral pH, but their solubility drastically increases as pH drops. Typically the critical pH for dental enamel is around 5.5 and for dentin 6.2. Buffering of acids (i.e. pH normalisation) and limiting the duration of periods of pH drop resulting from metabolic acid production by saccharolytic bacteria at carbohydrate exposure may
prevent demineralisation and promote remineralisation of the hydroxyapatite crystals. Calcium, phosphate, and fluoride in saliva, plaque fluid, and the inter-crystal water are key components for maintaining intact hydroxyapatite crystals. If appropriate concentrations of these ions are available (ionic equilibrium), demineralised crystals may re-mineralise when pH rises. Thus, any actions contributing to the ionic equilibrium may prevent demineralisation and promote remineralisation of the hydroxyapatite crystals (ten Cate et al., 2008).
In the absence of fermentable carbohydrates, no clinically relevant reduction on plaque pH may be expected by the consumption of sugar-free chewing gum (FDA, 1996; Edgar, 1998; Imfeld, 1999; Touger-Decker and van Loveren, 2003).
3.1. Neutralizacja kwasu w osadzie nazębnym (ID 1150)
The pH in dental plaque can be measured by established methods (Lingström et al., 1993). Saliva contains bicarbonate, phosphates and peptides, which contribute to buffering of acids (Wong, 2008). Secretion of bicarbonate increases markedly as saliva flow rate increases (Anderson et al., 1998; Wong, 2008).
The evidence provided by consensus opinions/reports from authoritative bodies, reviews and scientific original papers shows that there is good consensus on the role of chewing (e.g., a gum) in the stimulation of saliva flow and the secretion of buffering components (Edgar, 1990; Edgar, 1998; Manning and Edgar, 1993; Edgar et al., 2004; Imfeld, 1999; Anderson et al., 1998; Wong, 2008). A large number of studies confirm that chewing a sugar-free chewing gum enhances saliva flow and counteracts pH drops upon sugar-induced acid production by oral bacteria in the plaque (Nyvad, 1995; Gopinath et al., 1997; Imfeld et al., 1995; Sjögren et al., 2002; Smith et al., 2004). However, plaque pH normalisation may revert (fall again) if chewing is terminated earlier than 20 minutes after the sugar challenge (Dawes and Dibdin, 2001). Therefore, chewing for at least 20 minutes after meals may be needed to obtain the benefit of plaque pH neutralisation (Edgar and Geddes, 1990). The effect of chewing on plaque pH neutralisation will depend on the integrity of the salivary gland parenchyma and on the individual´s secretory capacity (Screebny, 2000).
The Panel concludes that a cause and effect relationship has been established between the consumption of sugar-free chewing gum and plaque acid neutralisation.
3.2. Utrzymanie mineralizacji zębów (ID 1151)
De- and remineralisation cannot be studied directly in animals or humans (Manning and Edgar, 1992). However, extrapolations can be made from clinical signs of net demineralisation, and from experimental studies using microradiography and/or measuring calcium release (ten Cate et al., 2008). Such studies provide a sufficient body of evidence to support that saliva stimulation by gum chewing is beneficial for tooth crystal de- and remineralisation balance (Manning et al., 1992; Manning and Edgar, 1998).
Studies in children from six years through school ages consistently show that children chewing sugar- free gums 3-5 times a day for 5-20 minutes after meals have significantly less persistent demineralisation of the tooth tissues, i.e. dental caries, than control children not chewing a gum (Mäkinen et al., 1995a, 1995b, 1996; Kandelman and Gagnon, 1990; Szöke et al., 2001; Beiswanger et al., 1998; Machiulskiene et al., 2001). These studies have been conducted in different parts of the world, including the European Union. Such studies are not available for adults or the elderly. However, in situ studies in adults strongly support that chewing a sugar-free gum prevents progression of demineralisation upon exposure to 10% sucrose (Kashket et al., 1989), and promotes remineralisation of artificial caries on enamel blocks worn in the mouth (Leach et al., 1989; Manning et al., 1992). One study did not find any additional remineralisation of artificial caries when sugar- free gum was chewed compared to no gum (Creanor et al., 1992) The Panel notes that, although the
vast majority of the studies presented on the effects of chewing a sugar-free gum on tooth mineralisation have been conducted in children populations, the biological plausibility for the effect applies to adult populations as well.
A further indirect support of an important role for saliva flow in the de- and remineralisation processes is that conditions where saliva is lacking or severely reduced are associated with rampant persistent tooth demineralisation (Imfeld, 1999; Screebny, 2000).
In weighing the evidence, the Panel took into account the consistent, positive results obtained in numerous clinical trials investigating the effects of sugar-free chewing gum consumption on net tooth mineralisation and 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 the maintenance of tooth mineralisation.
3.3. Zmniejszenie suchości w jamie ustnej (ID 1240)
The evidence provided by consensus opinions/reports from authoritative bodies, reviews, and scientific original papers shows that there is good consensus on the role of chewing (e.g., a gum) in the stimulation of saliva flow and associated secretion of salivary components (Edgar, 1990; Edgar et al., 2004; Imfeld, 1999; Anderson et al., 1998; Wong, 2008). The net effect, however, depends on the individual's secretory capacity of the salivary glands (Screebny, 2000). Increased saliva flow leads to the reduction of oral dryness.
The Panel concludes that a cause and effect relationship has been established between the consumption of sugar-free chewing gum and reduction of oral dryness.
3.4. Osiąganie lub utrzymywanie prawidłowej masy ciała (ID 1152)
The orosensory stimulation associated with eating is key to the development of satiation. Foods that require a greater amount of chewing, and hence are present in the mouth for longer, appear to enhance the orosensory stimulation, resulting in a greater suppression of appetite (Lavin et al., 2002) and food intake (Hetherington and Boyland, 2007). However, it is not clear whether these short term effects on food intake are maintained over time.
Copies of a petition to the United States Food and Drug Administration (FDA) by the Calorie Control Council and an acknowledgement of receipt from the FDA to the petition were provided as supporting evidence for this claim. However, this document does not appear to contain a response from FDA (Citizen Petition, 2003; FDA, 2004).
Studies cited in the petition from The Calorie Control Council evaluated effects of polyols and synthetic sweetening agents used in sugar-free products on weight maintenance as part of a complete diet-and-exercise programme (Berryman et al., 1968; Kanders et al., 1988, 1996; Blackburn et al., 1997; Morris et al., 1989; Tordoff and Alleva, 1990; Raben et al., 2002). However, sugar-free chewing gum was not directly tested in any of the cited studies. The remaining human studies contained within the petition report data on food intake and/or appetite but did not address the influence of sugar-free chewing gum on body weight and were thus not considered pertinent to the claimed effect.
Of the three papers provided in support of the claim, two related to sugar-free chewing gum and one to sugar-free pastilles. However, none of these studies considered the influence of these products on body weight and were thus not considered pertinent to support the claimed effect (Hetherington and Boyland, 2007; Levine et al., 1999, Lavin et al., 2002).
In weighing the evidence, the Panel took into account that no studies were presented on the effects of sugar-free chewing gum consumption on either body weight loss or body weight maintenance.
The Panel considers that a cause and effect relationship has not been established between the consumption of sugar-free chewing gum and the maintenance or achievement of a normal body weight.
