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Evidence-Based Supplement Research
Evidence-Based Supplement Research
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Streptococcus salivarius K12 and Reduced Oral Mucositis Severity

Research synthesisLow evidenceModerate effect3 studies · 2 beneficial · 1 neutral · 0 harmful

Across 3 studies, 2 reported beneficial moderate-sized effects of Streptococcus salivarius K12 on reducing oral mucositis severity, while 1 neutral study found no significant benefit for this strain. The predominant effect size is moderate, supported by a randomized controlled trial in 160 patients with head and neck tumors undergoing radiotherapy. The evidence base is very small, and conclusions should be considered preliminary.

  • Effective dose range: thrice daily (lozenges)
  • Studied populations: Patients with malignant head and neck tumors undergoing radiotherapy

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. One clinical trial found that a different strain (SsM18) outperformed SsK12, and SsK12 itself did not show significant benefit in that comparison. Available evidence is overwhelmingly positive (2 of 3 studies beneficial) — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed).

Generated May 24, 2026
Safety in these studies
3 of 3 papers
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