The anxiolytic effect of probiotics: A systematic review and meta-analysis of the clinical and preclinical literature.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of clinical and preclinical trials
PubMed 29924822 · doi:10.1371/journal.pone.0199041
What was done
Authors conducted a systematic review and meta-analysis of PubMed, PsycINFO, and Web of Science databases to evaluate the effect of probiotics on anxiety in preclinical animal models and human clinical studies. Subgroup analyses evaluated healthy versus diseased animals, specific probiotic species, and clinical versus healthy human samples.
What was found
Data were analyzed from 22 preclinical studies (743 animals) and 14 clinical studies (1,527 individuals): - Preclinical: Probiotics significantly reduced anxiety-like behavior overall (Hedges' g = -0.47, 95% CI -0.77 to -0.16, p = 0.004), with significant reductions seen only in diseased animals. Species-level analyses identified only *Lactobacillus rhamnosus* as effective. - Clinical: Probiotics did not significantly reduce anxiety symptoms in humans (Hedges' g = -0.12, 95% CI -0.29 to 0.05, p = 0.151), with no difference between healthy and clinical samples.
Why it matters
Preclinical evidence indicates anxiolytic potential for probiotics (notably *L. rhamnosus* in diseased models), but these findings have not translated into statistically significant anxiety reduction in human clinical studies.
Limits
Preclinical species-level analyses were broadly underpowered. Clinical studies included relatively few samples of clinically anxious populations, and the abstract provides no information regarding strain-specific dosing, treatment duration, or long-term outcomes.
Cited by
- context Lactobacillus rhamnosus probiotic strains have been shown to reduce anxiety in human clinical trials.