This course was published in the May 2016 issue and expires May 31, 2019. The authors have no commercial conflicts of interest to disclose. This 2 credit hour self-study activity is electronically mediated.
After reading this course, the participant should be able to:
- Provide the definition of a sugar alcohol.
- Identify the different types of sugar alcohols.
- Discuss the research behind the use of sugar alcohols in caries prevention.
Upon ingestion of fermentable sugars such as sucrose, glucose, and fructose, acidogenic bacteria produce acid that can lower the pH of dental biofilm to levels that cause demineralization of teeth.8 Among the various dietary sugars, sucrose is thought to be the most cariogenic. Sucrose is readily fermented by cariogenic bacteria and serves as a substrate for synthesis of extracellular and intracellular polysaccharides that play roles in bacterial adhesion to enamel.9 The extracellular polysaccharides also may increase the porosity of the biofilm, thereby facilitating the diffusion of sugars to the microbiota in the deepest parts of the biofilm.10 High-sucrose biofilms also have notably lower concentrations of calcium, phosphate, and fluoride, thus limiting tooth remineralization.11
Recently, the World Health Organization (WHO) recommended reducing the intake of “free sugars” while keeping sugar consumption to less than 10% of total energy intake.12 Free sugars consist of added (monosaccharides and disaccharides) and naturally occurring sugars found in food products.
There has been ongoing interest in the use of sugar alcohols to replace traditional sugars in light of potential health benefits such as reduced cariogenicity and fewer calories, as well as decreased glycemia and insulinaemia.13 This is because sugar alcohols are hydrogenated carbohydrates that are not readily metabolized by bacteria, making them less cariogenic when used as alternatives to dietary sugars, especially sucrose.14 The defining characteristic of sugar alcohols is the presence of an alcohol group in place of carbonyl group in the aldose and ketose moieties of mono-, di-, oligo-, and polysaccharides.13 Sugar alcohols also are referred to as polyol/polyhydric alcohol (eg, compounds containing three or more hydroxyl groups). Polyols can be acyclic compounds such xylitol, erythritol, and sorbitol, or cyclic polyols such as myo-inositol.15
As noted above, the noncariogenicity is common to all sugar alcohols because they are scarcely metabolized by microorganisms in the dental plaque.16 Thus, sugar alcohols can be classified as hypo- or nonacidogenic, with reduced or virtually no extracellular polysaccharide production.17 The fact that sugar alcohols do not produce extracellular polysaccharides is believed to be one of the reasons for their proven noncariogenicity. Another beneficial effect of sugar alcohol-based chewing gums is that chewing stimulates salivary secretion.18 Saliva can reduce caries due to its mechanical cleansing/flushing action, its ability to deliver ions for remineralization and buffer plaque acids, and via its own antibacterial properties.19
In 2010, Makinen15 suggested that the efficacy of sugar alcohols for caries prevention can be determined by each molecule’s number of hydroxyl groups, with erythritol ? xylitol > sorbitol. Yet the effect on caries rates between erythritol and xylitol is not fully established.15 In 1989, Grenby and Mistry20 reported that the amount of polysaccharide matrices synthesized by incubated microorganisms varied between sugar alcohols, with sorbitol > mannitol > lactitol > xylitol.
Because sugar alcohols are poorly metabolized, they are only partially digested and absorbed in the small intestine. As such, sugar alcohols may contribute to more frequent bowel movements, increased flatulence, and diarrhea. Tolerance to sugar alcohols may vary from person to person, but most adapt to polyols within a few days.21
Based on the evidence indicating that replacing sugars in the diet with sugar alcohols reduces the risk of dental caries, the United States Food and Drug Administration (FDA) approved a “do not promote dental caries” claim for various sugar alcohols such as xylitol, sorbitol, erythritol, mannitol, maltitol, hydrogenated starch hydrolysate (HSH), and lactilol.22 The FDA recently added isomalt to this list.23 The purpose of this paper is to provide an evidence-based update on the commonly used sugar alcohols and their role in caries prevention.
Xylitol (C5H12O5) is a sugar alcohol that is a five-carbon sugar. It naturally occurs in many fruits and vegetables and is produced commercially from plants such as birch and other hard wood trees.24 Xylitol is the most studied and thought to be most effective among sugar alcohols in reducing dental caries. However, there are conflicting results from research regarding the role of xylitol in caries prevention.
Twetman25 reported that xylitol reduced dental caries when given in doses of at least 5 g three to four times per day. This article suggested that xylitol is nonfermentable, reduces the volume of dental plaque, prevents decreases in plaque pH, exerts a stimulating effect on saliva, and promotes selection of less virulent xylitol-resistant mutans streptococci (MS).25
A systematic review was conducted in 2008 on the use of xylitol as part of an oral hygiene regimen to prevent caries. This review included two randomized clinical trials and four controlled clinical trials that compared xylitol chewing gum with no chewing gum. In their conclusions, authors noted that research gaps existed around the dose-response relationship and relative efficacy of different sugar alcohols.26 Another systematic review by Antonio et al27 concluded that xylitol-based candies and lozenges may help reduce the risk of noninterproximal caries but the level of evidence was noted as inconsistent and of limited quality.
Major health organizations have expressed limited recommendations regarding the use of xylitol for the prevention of dental caries. A systematic review sponsored by the American Dental Association (ADA) Council on Scientific Affairs recommended that xylitol chewing gum marginally reduces the incidence of caries.28 The 2014 US Preventive Services Task Force reported insufficient evidence to formally recommend xylitol’s routine use for caries prevention.29 A Cochrane review found low-quality evidence to support the use of fluoride toothpaste containing xylitol over fluoride-only toothpaste for preventing dental caries in children’s permanent teeth, as well as insufficient evidence to support the role of other xylitol interventions in caries prevention.19 In addition, the American Academy of Pediatric Dentistry (AAPD) revised their policy on xylitol use in 2015 stating that the results from trials of xylitol aimed at reducing dental caries, transmission of MS from mothers to children, and reduction of MS levels in children varied and were inconclusive. The AAPD policy emphasized that most studies used very large doses and frequencies, which may be unrealistic in clinical practice.30
In summary, the three possible ways in which xylitol may reduce caries are by substitution of cariogenic free sugars, saliva stimulation, and a possible antibacterial effect. The literature suggests that xylitol may be effective against S. mutans when given above the daily dose threshold of 5 g to 6 g per day in three or more divided doses. However, it is difficult to conclude if this anti-caries effect is over and above sugar substitution and saliva stimulation.19 Therefore, there is low-quality evidence that supports the inclusion of xylitol in a caries prevention regimen.
The sugar alcohol sorbitol (C6H14O6) is a bulk sweetener naturally found in some fruits and manufactured commercially from dextrose produced from cornstarch.24,31 Though the mechanism of anti-cariogenic action is the same for sorbitol as for other sugar alcohols, Ikeda32 reported that MS can metabolize sorbitol and produce acid. The amount of acid produced, however, was far smaller than that produced from sucrose.
Van Loveren17 concluded that most clinical trials with sorbitol-sweetened gums have a caries preventive effect in comparison with no gum use. Due to the limited number of studies included in this review, however, the caries preventive effect was difficult to quantify.17 Deshpande and Jadad26 concluded from a systematic review that sorbitol-alone chewing gum reduced dental caries, but there is a research gap regarding the dose-response relationship. Conflicting evidence regarding the efficacy of sorbitol was reported by Splieth et al,33 who found that the consumption of five xylitol lozenges per day for 4 weeks reduced acidogenicity of plaque. Such effects were not seen with sorbitol.
Makinen34 reported in 2011 that dental plaque can become adapted to sorbitol and its efficacy may be weaker than xylitol. Mickenautsch and Yengopal35 concluded from a systematic review that the evidence to support the use of xylitol over sorbitol is contradictory, with studies having high risk for bias and other confounders. They recommended that more high-quality randomized clinical trials be conducted to provide conclusive evidence regarding the efficacy of sorbitol.
Erythritol (C4H10O4) is a natural tetritol sugar alcohol with four hydroxyl groups. It is a zero calorie sweetener and the newest sugar alcohol to be manufactured from cornstarch via a fermentation process. It occurs naturally in fruits, mushrooms, and fermentation-derived foods such as wine and cheese. Erythritol is rapidly absorbed in the small intestine, reducing the likelihood of laxative effects and increased flatulence.24,31
In 2013, Runnel et al36 studied the effects of 3 years of erythritol candy consumption in school children. They found lower levels of acetic acid and propionic acid in dental plaque, as well as a reduction in oral counts of MS when compared with the xylitol and sorbitol groups.36 Honakala et al37 conducted a randomized clinical trial on school children that compared caries variables in long-term users of erythritol or xylitol candy as compared with a control (sorbitol candy) on dental caries. The children consumed four erythritol, sorbitol, or xylitol candies three to four times a day in school for 3 years. Daily intake of these polyols was about 7.5 g, and caries data were collected at 12 months, 24 months, and 36 months using the International Caries Detection and Assessment System. The fewest number of lesions and the longest time to develop caries were found in the erythritol group.37 In summary, erythritol is thought to be comparable to xylitol in caries prevention; however, more research is needed to support this claim.
Mannitol (C6H14O6) is a sugar alcohol similar to sorbitol. It is found in fruits, leaves, and other parts of plants and mushrooms. For commercial purposes, it is manufactured from fructose, which is derived from cornstarch.
Deshpande and Jadad26 published a systematic review that reported that a combination of sorbitol and mannitol did not affect dental caries with statistical significance. In summary, there is inadequate evidence to support the use of mannitol alone for caries prevention.
Maltitol (C12H24O11) is a sugar alcohol that is a reduced calorie bulk sweetener manufactured by hydrogenating maltose, which is derived from cornstarch.24,31 Birkhed et al38 evaluated the effect of maltitol lozenges over 3 months and observed no statistical significant difference in relative numbers of facultative anaerobic bacteria. Edgar and Dodds18 reported that maltitol affects plaque by increasing salivary flow. Holgerson et al39 conducted a randomized clinical trial among school children and reported that xylitol or sorbitol/maltitol reduced the amount of acid production in saliva and dental plaque, but only xylitol interfered with microbial composition. In another randomized clinical trial, Lenkkeri et al40 studied caries preventive effects of xylitol/maltitol and erythritol/maltitol lozenges in school children older than 4. These interventions did not provide additional caries-preventive benefits when compared with comprehensive prevention. Thabuis et al41 conducted a randomized clinical trial on maltitol and xylitol chewing gums in China. The maltitol group showed higher plaque pH and reduction in cariogenic bacteria in the 4-week evaluation. They concluded that sugar-free chewing gums with either maltitol or xylitol could reduce plaque acidogenicity by decreasing the level of oral bacteria present.41 In summary, there is some evidence to support that maltitol affects bacterial acidogenicity but the evidence is lacking on whether it helps prevent caries.
Isomalt (C12H24O11), a sugar alcohol of hexopyranosyl-hexitol type, is similar to maltitol. It is derived from sucrose with the original glucose-fructose bond remaining intact. The glucose portion is unchanged but the fructose portion is converted into equal amounts of sorbitol and mannitol. As such, isomalt is a mixture of two disaccharide alcohols: gluco-mannitol and gluco-sorbitol.24,31
Out of the four papers identified that explored isomalt for caries prevention, only one was found to be somewhat relevant, with the effect of isomalt on de- and remineralization of bovine enamel lesions in vitro and in situ.42 The authors reported that isomalt facilitated tooth remineralization. In summary, there is inadequate evidence to support the use of isomalt for caries prevention.
HYDROGENATED STARCH HYDROLYSATE
HSH is a bulk sweetener produced by partial hydrolysis of corn, wheat, or potato starch with subsequent hydrogenation of various starch fragments. HSHs include hydrogenated glucose syrups, maltitol syrups, and sorbitol syrups.24,31
There is little evidence to support the efficacy of HSH in caries prevention. In 1979, Birkhed et al38 evaluated the effect of HSH lozenges over 3 months and observed no statistical significant difference in relative numbers of facultative anaerobes. Thus, there is inadequate evidence to support the use of HSH for caries prevention.
The use of sugar alcohols, especially xylitol, remains popular. This has resulted in numerous confections containing xylitol such as candies, lozenges, syrups, chewing gums, toothpastes, and wipes being marketed for caries prevention. It seems prudent that dentists and dental hygienists be well-versed with the evidence supporting/refuting the use of such products.
If sugar alcohols are used to replace sugars in between-meal snacks, a reduction in caries may occur. However, there is inconclusive evidence to support the therapeutic effect of commercially available products containing sugar alcohols in various forms and dosages.30
Based on the literature, the following can be observed regarding sugar alcohols:
- Sugar alcohols do not promote dental caries and are considered passively noncariogenic.
- The beneficial effects of sugar alcohols may be attributed to the fact that they are nonfermentable and/or promote additional saliva production. However, their abilities as cariostatic agents are not fully established.
- Currently xylitol is the most promising sugar alcohol for caries prevention but effective doses appear high and remain somewhat unclear. Furthermore, the high dosages used in most studies may be impractical for everyday living.
- Considering the inadequate evidence of efficacy and possible gastric side effects, it may be premature to support the routine use of any sugar alcohols in caries prevention.
- National Institute of Dental and Craniofacial Research. Oral Health in America: A Report of the Surgeon General. Available at: nidcr.nih.gov/ Data Statistics/SurgeonGeneral/sgr/welcome.htm. Accessed April 15, 2016.
- Keyes PH. Infectious and Transmissable Nature ofExperimental Dental Caries. Arch Oral Biol.1960;1:304–320.
- Bowden GH. The microbial ecology of dental caries. Microbial Ecology in Health and Disease.2000;12:138–148.
- Gustafsson BE, Quensel CE, Lanke LS, et al. The Vipeholm dental caries study; the effect of different levels of carbohydrate intake on caries activity in 436 individuals observed for five years. Acta Odontol Scand. 1954;11:232–264.
- Harris R. Biology of the children of HopewoodHouse, Bowral, Australia. 4. Observations on dental caries experience extending over five years (1957–61). J Dent Res. 1963:1387–1399.
- Scheinin A, Mäkinen KK, Ylitalo K. Turku sugar studies. V. Final report on the effect of sucrose,fructose and xylitol diets on the caries incidence in man. Acta Odontol Scand. 1976;34:179–216.
- Sheilham A, James WPT. Diet and dental caries:the pivotal role of free sugars reemphasized. J Dent Res. 2015;94:1341–1347.
- Stephan RM. Intra-oral hydrogen ion concentration associated with dental caries activity.J Dent Res. 1944;23:257–265.
- Tinanoff N, Tanzer JM, Freedman ML. In vitro colonization of streptococcus mutans on enamel.Infection and Immunity. 1978;21(3):1010–1019.
- Rölla G. Why is sucrose so cariogenic? The role of glucosyltransferase and polysaccharides. Scand J Dent Res. 1989;97:115–119.
- Paes Leme AF, Koo H, Bellato CM, Bedi G, Cury JA.The role of sucrose in cariogenic dental biofilmformation—new insights. J Dent Res. 2006;85:878–887.
- World Health Organization. Guideline: Sugars Intake for Adults and Children. Available at: who.int/nutrition/publications/guidelines/sugars_intake/en.Accessed April 15, 2016.
- Livesey G. Health potential of polyols as sugarreplacers, with emphasis on low glycaemicproperties. Nutr Res Rev. 2003;16:163–191.
- Imfeld T. Efficacy of sweeteners and sugarsubstitutes in caries prevention. Caries Res.1993;27(Suppl 1):50–55.
- Makinen KK. Sugar alcohols, caries incidence,and remineralization of caries lesions: A literaturereview. Int J Dent. 2010;2010:981072.
- Tinanoff N, Palmer CA. Dietary determinants of dental caries and dietary recommendations for preschool children. J Public Health Dent. 2000;60:197–206.
- van Loveren C. Sugar alcohols: What is theevidence for caries-preventive and cariestherapeutic effects? Caries Res. 2004;38:286–293.
- Edgar WM, Dodds MW. The effect of sweeteners on acid production in plaque. Int Dent J. 1985;35:18–22.
- Riley P, Moore D, Ahmed F, Sharif M,Worthington HV. Xylitol-containing products for preventing dental caries in children and adults. Cochrane Database Syst Rev. 2015;26:CD010743.
- Grenby TH, Mistry PM. Studies of the dentalproperties of lactitol compared with five other bulk sweeteners in vitro. Caries Res. 1989;23:315–319.
- Calorie Control Council. Polyols and Gastro-intestinal effects. Available at: polyol.org/ frequently asked-questions/fap-g. Accessed April 15, 2016.
- Office of Federal Register, General ServicesAdministration, Code of Federal Regulations. Title 21 Section 101, Food Labeling: Health Claims; Sugar Alcohols and Dental Caries. Available at: federalregister.gov/a/96-2148. Accessed April 15,2016.
- Office of Federal Register, General ServicesAdministration, Code of Federal Regulations. Title21, Section 101, Food Labeling; Health Claims; Dietary Noncariogenic Carbohydrate Sweeteners and Dental Caries. Available at: federal register. gov/a/ E7-18196. Accessed April 15, 2016.
- Calorie Control Council. Facts About Polyols. Available at: polyol.org/facts-about-polyols. Accessed April 15, 2016.
- Twetman S. Treatment protocols: Nonfluoridemanagement of the caries disease process andavailable diagnostics. Dent Clin N Am. 2010; 54:527–540.
- Deshpande A, Jadad AR. The impact of polyol containing chewing gums on dental caries. A systematic review of original randomized controlled trials and observational studies. J Am Dent Assoc. 2008;139:1602–1614.
- Antonio AG, Pierro VS, Maia LC. Caries preventive effects of xylitol-based candies and lozenges: a systematic review. J Public Health Dent. 2011;71:117–124.
- Rethman MP, Beltrán-Aguilar ED, Billings RJ, et al. Nonfluoride caries-preventive agents: Executive summary of evidence-based clinical recommendations. American Dental Association Council on Scientific Affairs Expert Panel on Nonfluoride Caries-Preventive Agents. J Am Dent Assoc. 2011;142:1065–1071.
- Moyer VA, US Prevetive Services task Force.Prevention of dental caries in children from birththrough age 5 years: US Preventive Services Task Force recommendation statement. Pediatrics. 2014;133:1102–1111.
- American Academy of Pediatric Dentistry. Policyon the use of xylitol. Pediatr Dent. 2015/16;37:45–47.
- The Sugar Association. Sugar Alcohols. Available at: sugar.org/other-sweeteners/sugar-alcohols. Accessed April 15, 2015.
- Ikeda T. Sugar substitutes; reasons andindications for their use. Int Dent J. 1982;32:33-43.
- Splieth CH, Alkilzy M, Schmitt J, Berndt C, Welk A. Effect of xylitol and sorbitol on plaque acidogenesis.Quintessence Int. 2009;40:279–285.
- Makinen KK. Sugar alcohols sweeteners asalternatives to sugar with special consideration ofxylitol. Med Pric Pract. 2011;20:303–320.
- Mickenautsch S, Yengopal V. Effect of sylitolversus sorbitol: a quantitative systematic review ofclinical trials. Int Dent J. 2012;62:175–188.
- Runnel R, Makinen KK, Sisko H, Olak J, et al.Effect of three-year consumption of erythritol, xylitoland sorbitol candies on various plaque and salivary caries-related variables. J Dent. 2013;41:1236–1244.
- Honakala S, Runnel R, Saag M, et al. Effect oferythritol and xylitol on dental caries prevention inchildren. Caries Res. 2014;48:482–490.
- Birkhed D, Edwardsson S, Ahlden ML, Frostell G.Effects of 3 months frequent consumption ofhydrogenated starch hydrolysate (Lycasin), maltitol, sorbitol and xylitol on human dental plaque. Acta Odontologica Scandinavica. 1979;37:103–115.
- Holgerson PL. Sjostrom I, Stecksen-Blicks C,Twetman S. Dental plaque formation and salivary mutans streptococci in school children after use of xylitol-containing chewing gum. Int J Paediatric Dent. 2007;17:79–85.
- Lenkkeri AM, Pienihakkinen K, Hurme S, AlanenP. The caries-preventive effect of xylitol/maltitol anderythritol/maltitol lozenges: results of a double blinded, cluster-randomized clinical trial in an area of natural fluoridation. Int J Paediatric Dent. 2012;22:180–190.
- Thabius C, Cheng CY, Wang X, et al. Effects ofmaltitol and xylitol chewing gums on parametersinvolved in dental caries development. Eur J Paediatr Dent. 2013;14:303–308.
- Takatsuka T, Exterkate RA, Ten Cate JM. Effects ofIsomalt on enamel de- and remineralization, acombined in vitro pH-cycling model and in situ study. Clin Oral Investig. 2008;12:173–177.
From Dimensions of Dental Hygiene. May 2016;14(05):58–61.