Probiotics – defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host" - have been touted to become the next blockbuster functional ingredients in gum and mints by Euromonitor.
After evaluating data from 23 randomized clinical trials for probiotics and oral health, Maria Cagetti from the WHO Collaborating Centre of Milan for Epidemiology and Community Dentistry at the University of Milan, Italy and her co-authors concluded: “The use of probiotic strains for caries prevention showed promising results even if only few studies have demonstrated clear clinical outcomes.
“Therefore, the scientific evidence is still poor.”
Assessing the benefits
As reported in a special edition last year by NutraIngredients-USA, there are several different avenues for researchers to explore for probiotics to beneficially impact oral health, ranging from reducing dental plaque-related diseases, such as caries, gingivitis and periodontitis, or even reducing bad breath (halitosis).
Much of the research into the oral health benefits of probiotics has focused on Streptococcus mutans, the main bacteria associated with tooth decay. S. mutans binds to teeth via aggregation forming dental plaque. The bacteria then convert sugar to acid, which attacks the enamel of the teeth.
“In the two-thirds of the selected papers, probiotics have demonstrated the capacity to reduce S. mutans counts in saliva and/or plaque regardless of the product or strain used. However, this effect is variable and probably short-lasting,” wrote the authors.
Evolving science
However, recent data has indicated that caries may not be solely due to S. mutans. Indeed, as caries develop changes to the bacteria population on the tooth surface occur, shifting from a predominance of non-mutans streptococci and Actinomyces spp. to dominance of S. mutans and other non-mutans bacteria, including lactobacilli and Bifidobacterium spp., they explained.
“Different results are reported on the effect of probiotics on lactobacilli counts,” they wrote. “From the fourteen studies that evaluated the changes of this interim outcome, just two reported a positive result.
“The other interim outcomes considered (yeasts and plaque acidogenicity) were investigated in few studies and the results are unclear. Only three selected papers, two performed on children and another one on adults/elderly samples, had caries lesion development as outcome; two studies reported a statistically significant difference in caries increment after 15/21 months of probiotics use.”
Strains
The systematic review considered 23 randomized clinical trials, four of which were considered to be of excellent quality, nine were good quality, and 10 were deemed to be of poor quality.
The strains included in these studies, included, but were not limited to, Bifidobacterium animalis subsp. lactis BB-12, B. longum, B. animalis subsp. lactis DN 173010, Lactobacillus brevis, L. rhamnosus, L. acidophilus La-5, L. reuteri, and Saccharomyces cereviasae.
Bifidobacterium animalis subsp. lactis BB-12, “The effect of probiotics on the development of caries lesion seems encouraging, but to date, RCTs on this topic are insufficient to provide scientific clinical evidence,” they wrote.
Gum or toothpaste?
Cagetti and her co-authors added that, in order to attain the potential oral health benefits, probiotics would probably need to be consumer “almost daily, [… and there] may be a compliance aspect to be considered.
“However, for all products effective in caries prevention (i.e., fluoride and chlorhexidine) a frequent intake is required, so a possible way of administration could be to insert probiotic in other daily preventive products like toothpaste.”
Source: Nutrients
2013, 5(7), 2530-2550; doi:10.3390/nu5072530
“The Use of Probiotic Strains in Caries Prevention: A Systematic Review”
Authors: M. Grazia Cagetti, S. Mastroberardino, E. Milia, F. Cocco, P. Lingstrom, G. Campus