Research synthesisLow evidenceMixed effect size4 studies · 4 beneficial · 0 neutral · 0 harmful
Across 4 studies, 4 reported beneficial effects on immune function, with effect sizes ranging from small to moderate. Two studies were statistically significant. Evidence comes from a clinical trial in lambs, reviews in humans, and animal models; no consistent dose or duration data were available.
- Studied populations: Hu lambs (one study); general healthy adults (one review); immunosuppressed mice (one study)
Caveats: Evidence base is small (only 4 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). One study used Lactobacillus johnsonii, not Lactobacillus rhamnosus, and another studied Limosilactobacillus reuteri, while the relevant excerpt for the latter involved L. reuteri KBL346, not L. rhamnosus — findings may not be directly attributable to the supplement of interest. Study quality varied, with limited human trial data and animal/review studies dominating.
Generated Jul 18, 2026