ADDING FLUORIDE TO SUGAR—A NEW AVENUETO REDUCE DENTAL CARIES, OR A "DEAD END"?

D. BRATTHALL

D.E. BARMES1

Department of CariologyWHO Collaborating Centre for Education,Training and Research in Oral Health

University of LundTandvardshogskolan, Carl Gustavs Vag 34S-214 21 Malmo, Sweden•Oral Health Unit, WHOCH-1211 Geneva, Switzerland

Adv Dent Res 9(l):3-5, February, 1995

Abstract—A study group was formed in 1989 by the OralHealth Program of WHO, Geneva, to consider the possibilityof reducing dental caries by adding fluoride to sugar.Although a few promising clinical reports were available forreview, the group found that information was too scarce forfield trials to be recommended at this stage. Among the manyitems to be considered was what concentration of fluoride insugar could reasonably be regarded as cariostatic. Thus, thecommittee decided to initiate studies to obtain furtherbackground information. Unlike fluoridated salt, the conceptof fluoridated sugar does not involve trying to give theindividual a certain daily amount of fluoride, since dailyconsumption varies considerably. Instead, the idea is toelaborate on recent fluoride research showing that lowconcentrations of fluoride may also be beneficial, particularlyfor remineralization, if present at the sites where cariesoccurs.

This paper is an introduction to a set of papers describingthe background for the project, attempting to define optimalconcentrations for a clinical trial, and concluding that,although dental caries prevalence continues to decrease inindustrialized countries, the potential for large increasesremains in the huge populations in developing countries. Allavenues must be searched for a system which optimizespreventive efficiency. However, the possible introduction offluoridated sugar on the market is not related only to oralhealth. Safety aspects are of high priority, and several ethical,political, and economic factors must also be considered.These papers attempt to present the issue for broaddiscussion and to stimulate researchers to conduct furtherstudies which can guide decisions on whether fluoridatedsugar may be an avenue worth testing on a broader scale, orwhether the idea should be abandoned.

T he Oral Health Program of WHO has always givenprevention first place in its policies, strategies, andmethodologies and has progressively intensified thatapproach. Optimal use of fluorides in preventing

dental caries is a cornerstone of the Organization's three-pronged strategy, the other two main elements beingadequate oral hygiene and prudent dietary practice.

In the 1950's and '60's, water fluoridation was clearly themeasure of choice from among a limited range ofmethodologies. Gradually, the range broadened, andextensive research defined several other vehicles which couldtake their place in the "front line" of effective preventivestrategies at the community level, notably toothpaste (mainlytopical administration) and salt or milk (systemicadministration).

During this period of development starting in the 1950's,there were several who had the temerity to support sugarfluoridation as, conceptually, the most efficient way ofdelivering prevention, assuming of course that elimination ofsugars from the diet was unrealistic. The concept was notwell-received, particularly by those who wished toconcentrate on vehicles already shown to be effective and bythose who unequivocally condemned sugar as an undesirablecomponent of any diet. Nevertheless, pioneers of thisstrategy worked diligently over the years to show that anacceptable methodology might be feasible.

It was in this knowledge that WHO was approached bythe World Sugar Research Organization (WSRO) and askedto consider sugar fluoridation as a means for cariesprevention, in particular in developing countries at high riskof caries increase and without other means of prevention. Astudy group was formed in 1989 at the Oral Health Program,WHO (Geneva), including members of WHO and WSROstaff, experts in fluoride research, and representatives ofrelevant industries. Several meetings were held and extensiveliterature searches performed. As a result, it was agreed that,although a few promising clinical reports were available,information was too scarce for field trials to be recommendedat that stage. Among the many items to be considered wasthe need to assess what concentration of fluoride in sugarcould reasonably be regarded as cariostatic. At the sametime, it was decided to investigate several communitieswilling, in principle, to mount a field trial, provided asatisfactory methodology and protocol could be established.Thus, the committee decided to initiate studies to obtainfurther background information, some of which is presentedin this issue.

The first of these papers, entitled "Reducing theCariogenic Effect of Sugar by Adding Fluoride to Sugar—Project Background", by D.M. O'Mullane, summarizesfindings of the early studies on fluoridated sugar and defines

BRATTHALL & BARMES

TABLE 1

ADV DENT RES FEBRUARY 1995

CALCULATIONS FOR FLUORIDE INTAKE IF SUGAR IS MIXED WITH FLUORIDEAT DIFFERENT CONCENTRATIONS

If sucrose contains F atIf consumptionof sucrose in kg

per year is:

1007550454030252015105

then consumptionper day

in grams is:

274205137123110826855412714

20 ppm 10 ppm 5 ppmthe F intake per day in mg is:

2 ppm

5.484.112.742.472.191.641.371.100.820.550.27

2.742.051.371.231.100.820.680.550.410.270.14

1.371.030.680.620.550.410.340.270.210.140.07

0.550.410.270.250.220.160.140.110.080.050.03

the scope of the project. It is followed by two papersillustrating the effects of various fluoride concentrations ondental caries: "Effects on Demineralization of Enamel byFluoridated Sucrose. A Pilot Study in an in situ CariesModel" (Carlsson et al.) and "Effects of Fluoride-supplemented Sucrose on Experimental Dental Caries andDental Plaque pH" (Cutress et al).

The choice of the fluoride test solutions used in these twopapers requires comment. In the discussions leading to theaddition of fluoride to salt, it was believed that a certainamount of fluoride should be given daily to the individual.That amount of fluoride was based on data from, forexample, fluoride intakes in areas with natural "optimal"concentrations, leading to reduced caries levels. Seen fromthat perspective, salt is an adequate vehicle, since theconsumption of salt has a fairly limited variation, in terms ofdaily intake.

For sugar, a different approach has to be taken. It is not aquestion of trying to give the individual a certain amount offluoride. Sugar would not be ideal for such a purpose, sincedaily consumption varies considerably. Instead, the idea is totry to elaborate on recent fluoride research showing that lowconcentrations of fluoride may be beneficial, particularly forremineralization, if present at the sites where caries attacksoccur. Thus, the objective is to find the lowest effectiveconcentration, and to estimate if this concentration is withouthazardous effect, even in subjects with high sucroseconsumption.

In considering the papers referred to (Carlsson et al.;Cutress et a/.), it is important to notice whether the statedfluoride concentrations relate to dry weight sugar/fluoridestock material, or if working solutions are used. For example,in the Carlsson et al. paper, a 10-ppm fluoride/sugar mixture

(dry weight) did not show a significant effect, but in theCutress et al. paper, 2 ppm reduced enamel softening in alltest subjects. However, the 2-ppm concentration in the 10%test sucrose solution used corresponds to a dry weightfluoride/sugar equivalent of 20 ppm.

Analysis of data from the two studies indicates that, for asignificant effect on caries to be obtained, we need to useover 10 ppm fluoride (dry weight). To make it easier tocalculate the amount of fluoride that would be consumed ifall sugar sources were fluoridated, Table 1 shows somehypothetical examples, illustrating fluoride intakes at severaldifferent fluoride/sugar ratios, from 2 ppm to 20 ppm, dryweight. For example, if the total consumption of sugar peryear for an individual was 20 kg (55 g per day), and sugarwas fluoridated to 20 ppm, the total fluoride intake from thissource would be 1.10 mg per day.

By comparison, Table 2 presents data for fluoride-saltpreparations at concentrations commonly used or proposed(250 ppm is used in some countries). For example, if the totalconsumption of salt per day is 5 g, and salt is fluoridated to250 ppm, the total fluoride intake from this source would be1.25 mg per day.

In many Westernized countries, an average intake of about40 kg of sugar per year is common. For salt, a WHO studygroup on nutrition (WHO, 1990) recommended a daily upper-limit intake of 6 g salt.

Although the methods used in the two papers on fluorideconcentration may simulate natural conditions to a highdegree, only clinical surveys can define the real effect withcertainty. Using fluoridated products at meals, for example,may give prolonged fluoride actions due to better retentioncompared with a test system in which enamel specimens aredipped in a fluoride-containing solution for only a short time.

VOL9(1) ADDING FLUORIDE TO SUGAR

TABLE 2

CALCULATIONS FOR FLUORIDE INTAKE IF SALT IS MIXED WITH FLUORIDEAT DIFFERENT PROPORTIONS

If salt contains F at

If consumptionof salt in kgper year is:

18.259.133.651.830.37

then consumptionper day

in grams is:

50251051

250 ppm 200 ppmthe F intake from salt per day in mg is:

75 ppm

12.506.252.501.250.25

10.005.002.001.000.20

3.751.880.750.380.08

The last in the present set of papers is entitled "Fluorideand Sugar Intake among Adults and Youth in Mauritius.Preliminary Results", by Lahti et al. In discussions onpossible communities suitable for a field trial, it was realizedthat data regarding total fluoride intake, sugar consumption,and dietary patterns were not easily available fromdeveloping countries. In fact, the ideal total intake offluorides for any population seems to be difficult to define.Zimbabwe was the first country investigated as a possiblesite, but districts with suitable sugar consumption, cariespattern, and social conditions could not be identified.Mauritius may, according to Dr. Lahti's paper, offer moresuitable districts, but there still seems to be a lack ofinformation about total sugar intake among children with thehighest sugar consumption.

An ideal test area for a first trial should have a fairly highcaries incidence and substantial sugar consumption. Inaddition, other preventive fluoride programs should not bewidely in operation at the commencement of the project orplanned for the near future, and there should be no fluorosisproblem. Also, it should be possible for sugar consumption tobe monitored closely for estimation of exposure. It must beemphasized that, in the event a pilot project is successful, theresults cannot simply be extrapolated beyond the communityin which the project was conducted. For that reason,fluoridated sugar and sugar products should not be madeavailable in other communities until all the relevant factorsare fully evaluated.

In light of what has been achieved so far, it is necessary todecide what, if anything, should be done to pursue thisintriguing initiative. Although dental caries prevalence

continues to decrease in industrialized countries, the potentialfor large increases remains in the huge populations indeveloping countries. While it may be argued that the samefluoride vehicles which have been so successful in theindustrialized countries can be used to halt and reverse anydeterioration in oral health in developing countries, it isfundamental that all avenues be searched for a system whichoptimizes preventive efficiency and economic viability.

Needless to say, the issue of fluoridated sugar has alreadygenerated a lot of discussions and will definitely inspire morein the future. The WHO study group has received bothsupport for and critics of the issue. The possible introductionof fluoridated sugar on the market is an issue related not onlyto oral health, but also to safety, ethical, political, andeconomical matters.

The aim of this set of publications is to present the issuefor broad discussion and to stimulate researchers to conductfurther studies which can guide us in deciding whetherfluoridated sugar may be an avenue worth testing on abroader scale, or whether the idea should be abandoned.

ACKNOWLEDGMENTS

This project was supported by a grant from the World SugarResearch Organization.

REFERENCE

WHO (1990). Diet, nutrition, and the prevention of chronicdiseases. Report of a WHO study group. Technical ReportSeries 797. Geneva: WHO.