Research synthesisVery low evidenceModerate effect3 studies · 3 beneficial · 0 neutral · 0 harmful
Across 3 studies, all reported beneficial effects of Lactobacillus salivarius UCC118 on reduced fatigue, with a predominant moderate effect size. One statistically significant finding from a mouse study showed reduced fatigue biomarkers, while two narrative reviews supported a mechanistic role for gut microbiota in exercise-induced fatigue. The evidence base is very small and includes no human interventional trials with this specific strain, making conclusions preliminary.
- Studied populations: mice (preclinical); human studies referenced in reviews included athletes and exercise contexts
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). The only human-relevant evidence comes from narrative reviews, not direct interventional trials with this strain; the significant finding is from a mouse study. No doses or durations were consistently reported.
Generated Jun 11, 2026