Extended Safety Data for the Oral Cavity Probiotic Streptococcus salivarius K12

Area of Science:

• Microbiology
• Probiotics
• Food Safety

Background:

• Previous research assessed intrinsic characteristics of Streptococcus salivarius K12 for oral probiotic use.
• Studies covered antibiotic resistance, virulence factors, metabolic by-products, and genetic stability.

Purpose of the Study:

• To evaluate additional safety factors of Streptococcus salivarius K12.
• To assess genotoxicity, short- and long-term toxicity in rats, and natural occurrence in human saliva.
• To determine safe human dosing for oral cavity colonization.

Main Methods:

• Animal studies involved short- and long-term oral dosing of rats with S. salivarius K12.
• Genotoxicity was assessed using a bacterial reverse mutation assay (Ames test).
• Human saliva samples (n=780) were analyzed for bacteriocin phenotype, and colonization levels were studied in 100 subjects.

Main Results:

• No evidence of genotoxicity or acute/subacute toxicity was found in rats.
• S. salivarius K12 did not achieve higher persistence levels than naturally occurring strains in human subjects.
• Natural occurrence of similar bacteriocin-producing strains was confirmed in children's saliva.

Conclusions:

• Streptococcus salivarius K12 demonstrates no genotoxicity or toxicity.
• The bacterium's persistence in humans is comparable to naturally occurring levels.
• Combined with historical use, S. salivarius K12 is confirmed safe for human consumption as an oral probiotic.