Daniel Reis MA Graduate Student Clinical Psychology University of Kansas

No Evidence Probiotics Will Reduce Your Anxiety

MedicalResearch.com Interview with:

Daniel Reis MA Graduate Student Clinical Psychology University of Kansas

Daniel Reis

Daniel Reis MA
Graduate Student
Clinical Psychology
University of Kansas

MedicalResearch.com: What is the background for this study? What are the main findings?

Probiotics have generated considerable interest as a possible treatment for numerous forms of physical and mental illness. Preliminary evidence from both preclinical and clinical studies suggest that probiotics may be able to reduce anxiety. Our goal was to comprehensively review and summarize existing preclinical and clinical studies.

Overall, probiotic administration reduced anxiety-like behaviors in rodents, but only in those with some form of experimentally-induced disease (such as early-life stress or socieal defeat). Probiotics did not reduce anxiety in humans.

MedicalResearch.com: What should readers take away from your report?

  • Presently, probiotics are not supported as a treatment for anxiety in humans. However, to date, no clinical study of probiotics has recruited patients with clinically elevated anxiety. Given that probiotics only reduced anxiety in diseased animal models (all of which were associated with increased anxiety), it is possible that probiotics are only efficacious for severe anxiety.
  • Weight-adjusted probiotic dosages used in rodent trials were observed to be up to hundreds of times larger than those used in human trials.
  • Subgroup analyses of preclinical studies revealed that the probiotic species Lactobacillus rhamnosus​ had significant anxiolytic properties.

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

  • Future studies should examine the effects of probiotics on anxiety in clinically anxious populations.
  • Studies assessing the anxiolytic effect of probiotics in humans should consider using a higher probiotic dosage than those previously reported.
  • Lactobacillus rhamnosus should be investigated further for its anxiolytic potential.

The authors have no conflicts of interest to disclose.


Daniel J. Reis, Stephen S. Ilardi, Stephanie E. W. Punt. The anxiolytic effect of probiotics: A systematic review and meta-analysis of the clinical and preclinical literature. PLOS ONE, 2018; 13 (6): e0199041 DOI: 10.1371/journal.pone.0199041 

[wysija_form id=”3″]

The information on MedicalResearch.com is provided for educational purposes only, and is in no way intended to diagnose, cure, or treat any medical or other condition. Always seek the advice of your physician or other qualified health and ask your doctor any questions you may have regarding a medical condition. In addition to all other limitations and disclaimers in this agreement, service provider and its third party providers disclaim any liability or loss in connection with the content provided on this website.


Last Updated on June 22, 2018 by Marie Benz MD FAAD