Streptococcus salivarius M18
Oral probiotic strain · friendly bacteria native to healthy mouths
Streptococcus salivarius M18 is a friendly bacteria that naturally lives in healthy mouths. It is closely related to K12 but works on a different part of oral health. K12 is studied most for fresh breath. M18 is studied most for supporting healthy teeth and gums.* We pair them in every Fenn Method oral probiotic mint.
Streptococcus salivarius M18, in plain language.
Streptococcus salivarius M18 belongs to the same family of friendly bacteria as K12, naturally found in healthy mouths. Within that family, individual strains specialize:
- K12 produces compounds active against the bacteria behind bad breath (Burton et al. 2006).
- M18 produces a different set of compounds. They belong to the bacteriocin family: natural antibacterial molecules that slow the growth of bacteria associated with plaque buildup* (Wescombe et al. 2009).
Where M18 settles: the same spots as K12. Your tongue, the gum line, the inside of your cheeks. The compounds it makes work in those local environments.
Why pair the two strains: K12 covers fresh breath. M18 covers teeth and gum support.* Together they do more than either alone.
What M18 does in your mouth.
S. salivarius M18 settles into the same spots as K12: your tongue, the gum line, the inside of your cheeks. From there, it does two main jobs:
- It supports the bacterial balance around your teeth and gums.
Healthy gums depend on the right mix of bacteria. M18 helps maintain that balance.* - It helps slow plaque buildup.
Plaque is the film that forms when bacteria stick to your teeth. M18 makes them less able to stick.*
Like K12, M18 lasts in your mouth for one to three weeks per dose. Daily use is the protocol the research supports.
The evidence base.
M18 has a published research base around dental health markers, plaque levels, and the makeup of the oral microbiome during daily use.*
The research is solid, but smaller than the K12 base. We use both strains in Fenn Method because they work on different parts of oral health.
The M18 evidence base is solid but smaller than K12's. We do not claim M18 treats, cures, or prevents any disease. It supports healthy teeth and gums.*
Why 1 billion CFU.
Each Fenn Method oral probiotic mint delivers 1 billion CFU of S. salivarius M18. Same dose as K12. Same daily-use protocol.
That 1 billion is the minimum at the end of shelf life. Live probiotics lose count slowly over time, so we formulate with significant overage. In practice, every oral probiotic delivers a dose well above 1 billion CFU through expiration. The 1 billion floor is what we will stand behind on the label.
Pairing M18 with K12 is deliberate. K12 covers fresh breath. M18 supports healthy teeth and gums.* Together they do more than either alone.
Questions about M18.
Q.01 Is M18 a substitute for brushing?
Q.02 Will M18 help with gum sensitivity?
Q.03 Why pair K12 and M18?
Q.04 Is M18 safe alongside regular dental care?
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