Prebiotics and probiotics for depression and anxiety: A systematic review and meta-analysis of controlled clinical trials

Liu et al., 2019 | Neurosci Biobehav Rev | Meta Analysis

Citation

Liu Richard T, Walsh Rachel F L, Sheehan Ana E. Prebiotics and probiotics for depression and anxiety: A systematic review and meta-analysis of controlled clinical trials. Neurosci Biobehav Rev. 2019-Jul;102:13-23. doi:10.1016/j.neubiorev.2019.03.023

Abstract

With growing interest in the gut microbiome, prebiotics and probiotics have received considerable attention as potential treatments for depression and anxiety. We conducted a random-effects meta-analysis of 34 controlled clinical trials evaluating the effects of prebiotics and probiotics on depression and anxiety. Prebiotics did not differ from placebo for depression (d = -.08, p = .51) or anxiety (d = .12, p = .11). Probiotics yielded small but significant effects for depression (d = -.24, p < .01) and anxiety (d = -.10, p = .03). Sample type was a moderator for probiotics and depression, with a larger effect observed for clinical/medical samples (d = -.45, p < .001) than community ones. This effect increased to medium-to-large in a preliminary analysis restricted to psychiatric samples (d = -.73, p < .001). There is general support for antidepressant and anxiolytic effects of probiotics, but the pooled effects were reduced by the paucity of trials with clinical samples. Additional randomized clinical trials with psychiatric samples are necessary fully to evaluate their therapeutic potential.

Key Findings

Additional randomized clinical trials with psychiatric samples are necessary fully to evaluate their therapeutic potential.

Outcomes Measured

  • anxiety
  • depression

Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition anxiety

MeSH Terms

  • Anxiety Disorders
  • Controlled Clinical Trials as Topic
  • Depressive Disorder
  • Gastrointestinal Microbiome
  • Humans
  • Prebiotics
  • Probiotics

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Systematic Review
  • Vertical: probiotics-mood

Provenance


Source extracted via PubMed E-utilities API on 2026-04-09