Safety and Human Tolerance of Oral Probiotic Streptococcus Salivarius K12


Liaquat University of Medical & Health Sciences


Not yet enrolling


Strep Throat


Dietary Supplement: Oral probiotic Streptococcus salivarius K12 sachet

Study type


Funder types




Details and patient eligibility


Streptococcus salivarius K12, an oral probiotic strain, has emerged as a promising tool in promoting oral health. Found naturally in the mouth, S. salivarius K12 works by establishing itself in the oral cavity and producing antimicrobial compounds, such as bacteriocins, including salivaricin A2 (SalA2) and the 2,740-Da salivaricin B (SboB) lantibiotics, which inhibit the growth of harmful bacteria including Streptococcus pyogenes. By maintaining a healthy balance of oral microbiota, this probiotic may help prevent common oral health issues such as bad breath, throat infections, and tooth decay. While further research is needed to fully elucidate its mechanisms and efficacy, S. salivarius K12 holds potential as a natural and safe adjunct to oral hygiene practices for promoting overall oral health and hygiene.

Full description

Numerous clinical studies have delved into the therapeutic potential of Streptococcus salivarius K12 across a broad spectrum of health conditions including prevention of recurrent upper respiratory tract infection such as such as sore throat, tonsillitis, and pharyngitis, in both adults and pediatrics. However, despite this extensive exploration, only limited clinical trials have explicitly focused on assessing its safety profile and human tolerance. Therefore, the primary objective of the present clinical trial is to bridge this gap in knowledge by meticulously evaluating the safety and tolerance of Streptococcus salivarius K12 in human subjects. By conducting comprehensive assessments and closely monitoring participants' responses, this trial aims to elucidate crucial insights into the safety profile and human tolerance of this probiotic strain. The findings gleaned from this clinical trial will not only enhance our understanding of Streptococcus salivarius K12's safety but also provide invaluable guidance for its future evidence-based therapeutic applications in oral health management and disease prevention.


54 estimated patients




18 to 60 years old


Accepts Healthy Volunteers

Inclusion criteria

  • Adults, both male and female, aged 18 to 60 years.
  • Stable health condition with no acute illness at the time of enrollment.
  • BMI 18.5-35 kg/m2
  • No known food allergies or intolerances to probiotics
  • All clinical chemistry, hematology and urinalysis parameters and vital signs (blood pressure, respiratory rate, temperature, heart rate) within clinically acceptable ranges.
  • Ability and willingness to provide informed consent.
  • Must be willing to comply with study procedures and attend scheduled visits.

Exclusion criteria

  • Individuals with a history of severe allergies or adverse reactions to probiotics or any of the components of the study product.
  • Participants with a recent history of oral surgery or dental procedures within the past 4 weeks.
  • Individuals with severe dental problems or undergoing active dental treatment.
  • Individuals with a known diagnosis of systemic diseases affecting the oral cavity (e.g., oral cancer, Sjögren's syndrome).
  • Individuals with compromised immune systems, or a history of immunodeficiency disorders or undergoing immunosuppressive therapy.
  • Pregnant or breastfeeding females.
  • Current smokers or individuals who have quit smoking within the past 6 months.
  • Individuals currently using antibiotics or have used them within the past 4 weeks.
  • Individuals with a history of gastrointestinal disorders (e.g., inflammatory bowel disease, irritable bowel syndrome).
  • Individuals with unstable metabolic diseases/disorders, heart failure or a history of endocarditis.
  • Frequent user of alcohol or over the counter laxatives, or herbal-based supplements (but not vitamin supplements), or prescription drugs that may potentially influence the biomarkers to be measured in the study.
  • Those with any chronic systemic illness that might affect participation in the trial or interpretation of results.
  • Participants currently enrolled in another clinical trial involving probiotics or oral health interventions.
  • Those unable to adhere to the study protocol or unlikely to complete the study period due to anticipated relocation or other personal reasons.
  • Any other condition or circumstances that, in the opinion of the investigator, might compromise the safety of the participant or the validity of the study results.

Trial design

Primary purpose




Interventional model

Parallel Assignment


Double Blind

54 participants in 2 patient groups

Probiotic supplement group
Experimental group
Participants in this arm will receive a daily single sachet of oral probiotic Streptococcus salivarius K12 (Bactoblis®: containing ca. 10 billion CFU of S. salivarius K12) for 28-days. Participants will be followed for a further 2-months to assess for probiotic treatment safety and tolerance.
Dietary Supplement: Oral probiotic Streptococcus salivarius K12 sachet
Control group
No Intervention group
Participants in this arm will not receive probiotic supplementation. They will be followed in a similar way as the participants in the probiotic K12 group.

Trial contacts and locations



Data sourced from

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