BLIS M18 probiotics may reduce risk of dental caries

Despite major technological advances and various novel initiatives introduced by the dental profession, dental caries, one of the most common chronic diseases of childhood, continues to increase worldwide.

Recent studies by the Journal of Medical Microbiology and the Clinical, Cosmetic, and Investigational Dentistry may indicate that probiotics containing BLIS M18™ can reduce caries-related risk factors in children at high-risk for dental caries.

Both studies indicate that consuming slowly dissolving oral tablets containing BLIS M18 may lead to a reduction in dental plaque and mutans streptococci, particularly Streptococcus mutans and Streptococcus sobrinus, bacterial species closely tied to caries development.

These results may be attributed to the specific anticariogenic characteristics shown by the BLIS M18 strain. After colonizing the oral mucosa, BLIS M18 releases bacteriocins, which inhibit the growth of S. mutans, S. sobrinus and other pathogens found in caries development, as well as dextranase and urease, enzymes that catalyze the breakdown of dextran and plaque, and aids in increasing saliva pH.

Bacteriocin-Like-Inhibitory Substances (BLIS)

BLIS, one of the best studied probiotics for oral health, was developed by scientists at the University of Otago in New Zealand. A specific strain of Streptococcus salivarius, it secretes powerful antimicrobial molecules trademarked as BLIS.

Currently, multiple BLIS ingredients are available for probiotic manufacture, including S. salivarius BLIS K12™ and BLIS M18. The primary difference between K12 and M18 is health function. Although both BLIS probiotic strains begin by colonizing the mouth, K12 supports ear, nose, throat (ENT) and immune health while M18 predominantly supports dental health.

BLIS M18 utilizes multiple mechanisms to inhibit the growth of the bacteria in the mouth, including S. mutans.

Studying BLIS M18

The participants of the first study included 100 New Zealand children ranging in ages from 5 to 10 years who had previously experienced dental caries and at least three dental restorations (including one placed within the previous 12 months). Forty children were placed into the probiotic program while forty-three were placed in the placebo program.

Bacteria identified as a known cause of both dental caries or periodontal (gum) disease in humans were tested. Species that were found to be inhibited by BLIS M18 in this study included S. mutans, Actinomyces naeslundii, Actinomyces viscosus, Enterococcus faecalis, Lactobacillus spp. and S. sobrinus. Additional significant upper respiratory tract pathogens that were inhibited by M18 included all strains of S. pyogenes (strep throat), Streptococcus pneumoniae (pneumonia, meningitis, and ear infections), half of the Moraxella catarrhalis strains (ear infections), both Streptococcus agalactiae strains (neonatal sepsis) and half of the Staphylococcus aureus strains (frequently found in the nasopharynx and a common source of infections).

In the M18 group, nine subjects retained M18 populations that comprised at least 5 percent of their total salivary S. salivarius population at three months. Although only a small percentage of the participants’ mouths were successfully colonized with M18 during the study, the plaque scores of the nine well colonized participants presented a greater plaque reduction than both the entire M18- and placebo treated groups.

Only 22 percent of the M18 treatment group had detectable probiotic in their saliva at the end of the study, which indicates that any effects directly attributable to the presence of the probiotic are only likely to occur during the period of active dosing.

This observation contrasts to S. salivarius BLIS K12, a probiotic that has been shown to exhibit more persistent colonization of the human oral cavity. However, it is noteworthy that, since this trial was conducted, significant improvements have been introduced to the manufacturing process of BLIS M18, resulting in considerably improved colonization efficacy.

Scientists studied nearly 80 children aged between 6 and 17 at high risk for dental caries. Thirty-eight children were randomly assigned to receive slowly dissolving oral tablets in a probiotic that contained at least 1 billion colony forming units (CFUs) of BLIS M18 per tablet while the rest of the children in the study received no intervention at all (control).

Researchers observed a significant 30 percent reduction in caries development in the group that received treatment after 90 days. A 50 percent reduction in dental plaque and a 75 percent reduction in mutans streptococci were also reported.

Some improvements observed in this second study might be related to a better diet or changes in oral hygiene or fluoride program and cannot be linked to the treatment; however, others observable changes, including plaque amount and the reduction of mutans streptococci may be a direct result of S. salivarius M18 releasing toxins that kill mutans streptococci and dextranase and urease enzymes, which can lead to the development of dental caries.

Although these studies require confirmation in a larger, controlled trials with caries development as the primary outcome measure, these promising results suggest that BLIS M18 has the potential to complement a diligent oral hygiene program along with a nutritionally balanced diet to help fight the battle against tooth decay.


Francesco Di Pierro, Zanvit, A., Nobili, P. et al. Cariogram outcome after 90 days of oral treatment with Streptococcus salivarius M18 in children at high risk for dental caries: results of a randomized, controlled study. Clinical, Cosmetic and Investigational Dentistry. 2015. 7; 107-13. doi:

Jeremy P. Burton, Drummond, B.K., Chilcott, C.N. et al. Influence of the probiotic Streptococcus salivarius strain M18 on indices of dental health in children: a randomized double-blind, placebo-controlled trial. Journal of Medical Microbiology. 2013. 62(6); 875-84. doi: 10.1099/jmm.0.056663-0

Leave a Reply