Sweet teeth

“How gummy bears could keep your teeth healthy,” reads the headline of the Daily Mail . A study has given children gummy bears which were “supplemented by the natural sweetener xylitol, which stifles the growth of certain bacteria in the mouth”, the newspaper says. Eating four of the modified sweets three times daily caused the level of bacteria in the mouth to decline dramatically, making them a “weapon against tooth decay”, the newspaper adds.

This was a well-designed trial, which is part of a series of studies looking to find the optimal dose and method of delivery of xylitol to prevent dental caries. Xylitol is commonly found in chewing gum products, but xylitol gummy bears were considered safer for children than gum. However, this current research has only been carried out with a small number of children, and the sweets are not currently manufactured for sale. Further research will be needed to consider the safety and effectiveness of xylitol. For now, good dental care with daily teeth brushing and regular dental check-ups remain the best way to fight tooth decay.

Where did the story come from?

Kiet A Ly and colleagues of Northwest/Alaska Center to Reduce Oral Health Disparities and Department of Dental Public Health Sciences, School of Dentistry, University of Washington, US, carried out this research. The study was funded by the National Institute of Dental and Craniofacial Research and the Office of Head Start. Gummy bears containing xylitol were produced by Santa Cruz Nutritionals. It was published in the online peer-reviewed journal BMC Oral Health .

What kind of scientific study was this?

This was a preliminary randomised controlled trial in which children were given gummy bears containing either xylitol or maltitol to see whether there was a reduction in the levels of bacteria in saliva and dental plaque. The bacteria mutans streptococci (MS) and Lactobacillus spp. have both been implicated in the development of dental caries. The researchers also tried to work out the optimal dose of xylitol required. This is one of a number of studies that are being carried out to ascertain the optimal dose and method of delivery of xylitol to prevent dental caries.

This was a six-week study in which 154 children from a school in rural Washington were randomised to receive gummy bears containing either 15.6g or 11.7g of xylitol per day or 44.7g per day of maltitol. Maltitol was used as the control comparison rather than as an active treatment, as previous trials had demonstrated that it did not reduce MS levels in plaque. The average age of the children was 8.4 years. Children who had used antibiotics within the past two weeks or who were expected to require antibiotics, or those with a history of stomach upsets, were not included in the study.

Packages of gummy bears labelled with randomised ID numbers were distributed to the classrooms three times per day and were consumed at school with no packages or sweets sent home. Gummy bears in different packages were of the same size, colours and flavour, and neither the children nor the teachers were aware of the dose or sweetener that they were receiving. The 15.6g daily dose was four xylitol bears, the 11.7g dose, three xylitol and one maltitol bear, and the 44.7g maltitol control was four bears containing maltitol.

Classroom volunteers who had been trained in research principles distributed the packages, observed consumption and recorded any unconsumed bears and the number of children absent on that testing day. Parents were given information about adverse effects to look out for and report to research staff, such as bloating, stomach cramps, loose stools or diarrhoea.

Dental plaque samples were collected from the children by trained research staff at the start of the study and at the end of the study six weeks later. Statistical comparisons were used to compare levels of bacteria in the plaque at the start and end of the study in the different dose groups.

What were the results of the study?

At the start of the study 27.3% of the children did not have detectable MS bacteria in their plaque, and 35.1% did not have detectable Lactobacillus spp. bacteria. Nineteen per cent of children had high levels of MS bacteria, and of these 4.5% had extremely high levels. There was no difference in plaque bacteria levels between the children in the different randomised groups.

At six weeks, plaque sampling was completed in 97% of the children. However, only 77% of the total gummy bears had been eaten. This was mostly due to child absence, with 15% of the children frequently absent and consuming less than 50% of their allotted gummy bears. There was no difference in absence rates between the groups.

Significant reductions in MS plaque bacteria were seen in all groups, with no difference in the level of reduction between the three. Plaque levels reduced from detectable to non-detectable levels in 38 of the children, while they rose from non-detectable to detectable levels in two of the children. Lactobacillus spp. bacteria levels remained unchanged.

What interpretations did the researchers draw from these results?

The authors conclude that six weeks of xylitol- or maltilol-containing gummy bears consumed on a daily basis reduced MS bacteria levels in the plaque. They suggest that xylitol-containing gummy bears may be an alternative to xylitol-containing chewing gum for preventing caries, a suggestion that teachers and parents involved with this study were in agreement with. However, they say that further larger trials are required with xylitol due to the unexpected positive findings with maltitol.

What does the NHS Knowledge Service make of this study?

This was a well-designed and carefully controlled trial, which is part of a series of studies that are being carried out to decide the optimal dose and method of delivery for xylitol when used to prevent dental caries. However, although the reduction in plaque bacteria levels seen was considered to be “highly significant”, these results should be considered preliminary only. They have a number of limitations, which the authors openly acknowledge.

• The maltitol gummy bears were used as the control as they were not expected to reduce bacteria levels. However, this was found not to be the case, which limits the conclusions that can be made about the effectiveness of xylitol. It is suggested that the act of chewing might help reduce plaque levels of bacteria, but the authors discount this by referring to chewing gum studies conducted without xylitol, which have shown no effects.
• Compliance rates were low, with only 77% of the allotted gummy bears consumed. Aside from absence, this was also due to fluctuation in the cooperation of the children, e.g. some wanted to eat bears of one colour only. Although there was no difference between the three groups in the amount of gummy bears eaten, this reduces the statistical power of the study in its ability to detect reliable differences in the level of plaque bacteria between the start and end of the study.
• The school setting of the study also caused inherent limitations through school closures and early dismissals of the children, etc. Conversely, the institutional setting gives benefits in being able to administer the gummy bears and monitor xylitol consumption, which may not be possible in less structured environments.
• The quantity of dental plaque that the research workers obtained for analysis was not standardised, which may have affected the bacterial assessments.
• Although the researchers asked about adverse effects, such as gastrointestinal upsets, they have not been reported on by the study, and longer-term safety would need further investigation.
• Implementing such a healthcare intervention in the longer-term would require the agreement between all involved, e.g. all school administrative and teaching staff, health professionals, parents and children.

Future studies might also look at the ability of xylitol to reduce the number of teeth needing filling or extracting in children, as a more direct measure of tooth decay.

Children should aim to eat a balanced diet with sugary and sweetened snacks and drinks kept to a minimum. For now, good dental care with daily teeth brushing and regular dental check-ups remain the best way to fight tooth decay.