Identifying probiotics using healthy individuals for preventing oral disease

The oral microbiome consists of many hundreds of species of bacteria, some harmful and some beneficial. The importance of a healthy microbiome should be stressed not only because having clean, white teeth looks good but because diseases like periodontitis increase risk of other issues such as respiratory infections and inflammatory diseases. Having unhealthy teeth can cause more systematic problems than you would think. Probiotics, different from antibiotics, are one way that microbiome science is combating the colonization of harmful bacteria in the body. Many researchers have investigated using probiotics to maintain a normal healthy oral microbiome, and in a new study published last week, scientists researched probiotics that may reduce the smell of “bad breath” that is caused by volatile sulfur compounds, and prevent cavities and periodontitis.

The study, performed by researchers at the Yakult Central Institute for Microbiological Research in Tokyo, Japan (a division of Yakult, the makers of yogurts and probiotics),  was aimed toward finding new potential probiotic candidates. Thirty-two volunteers were recruited and selected based on factors such as non-smoking habits, no large cavities or bleeding on probing, and no bad breath. Oral bacteria samples were taken from multiple specific locations in the mouth of the volunteers. The bacteria were cultured in a lab and tested for the characteristics that follow: lack of production of volatile sulfur compounds (causes bad breath) and water insoluble glucan (causes cavities), antibacterial activity against bacteria that cause periodontitis, ability to healthily adhere to teeth and cells in the mouth, and caused no infections in an artificial mouth system or in a rat model.

After culturing in a lab and testing the criteria on 896 oral samples from the 32 participants, the study found that Lactobacillus crispatus YIT 12319, L. fermentum  YIT 12320, L. gasseri YIT 12321, and Streptococcus mitis YIT 12322 are good candidates for probiotics.  The next step is to now test for these probiotics’ effects in the mouths of many people, and likely develop a product.  Interestingly, L. crispatus and L. gasseri are two of the major bacterial strains found in a healthy vaginal microbiome, and perhaps this suggests a route of access for these bacteria to access the vagina. In any case, the promise of new ways to help maintain a healthy oral microbiome is exciting, and it is encouraging to read papers from major companies that have the ability to actually manufacture products in this space.

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