Gut Brain Evidence

Evidence map

Probiotics mood: what the evidence base looks like

14 publications, 8 of them trials and 6 syntheses. This page describes the shape of that literature rather than summarising its conclusions.

Updated 4 min read 14 citations

Shredded fermented white cabbage served in a dish
Sauerkraut is preserved by lactic acid bacteria converting the cabbage's own sugars. Eugene Zelenko · CC BY-SA 4.0 · Wikimedia Commons
What the evidence on probiotics mood is made of Of 14 publications on this topic, the breakdown by study type: 6 meta-analysis, 8 randomised trial. 68meta-analysis (6)randomised trial (8)
14 publications, by study type. Volume is not strength — the same count can be a settled question or a pile of commentary, and which one it is depends almost entirely on this breakdown. Harvested from PubMed and Crossref; publication type as recorded by the source.

What this literature is made of

This is a well-developed evidence base: multiple syntheses sitting on a substantial body of trials. Questions here are usually about applicability rather than about whether an effect exists.

The distinction that matters most is between synthesis and primary research. A meta-analysis pools trials and is the closest thing to a settled answer a field produces. A narrative review is one group's reading of the same material and can be selective without being dishonest. Counting them together, which most citation counts do, obscures exactly the thing you want to know.

When the probiotics mood literature was published Publication years for the 14 papers on this topic, grouped into bands from before 2015 through to 2023 onwards. 2023 onwards8 papers2020-20224 papers2015-20192 papers
Still active. The most recent paper here is from 2025, so this is a field where an answer written today may not hold for long. Publication years as recorded by PubMed and Crossref.

How this page is built

Everything above is computed from the citations this site harvested from PubMed and Crossref, not written by hand. When the weekly harvest finds a new paper on this topic, these counts change and the characterisation changes with them. That is the point: a hand-written claim about how strong an evidence base is starts decaying the day it is written.

Publication type is taken as the source records it. That is imperfect — journals label inconsistently, and a paper indexed as a "review" may be a systematic one — so treat the bands as approximate. They are accurate enough to distinguish a trial literature from a commentary literature, which is the distinction that matters.

Working laboratory bench set up for formulation chemistry
Cjp24 · CC BY-SA 3.0 · Wikimedia Commons

The strongest work on this topic

Ordered by study design first, then recency. The full set is listed in the references below.

  1. Effects of Prebiotics and Probiotics on Symptoms of Depression and Anxiety in Clinically Diagnosed Samples: Systematic Review and Meta-analysis of Randomized Controlled Trials — Asad A, Kirk M, Zhu S et al., 2025, meta-analysis
  2. A systematic review of the beneficial effects of prebiotics, probiotics, and synbiotics on ADHD — Allahyari P, Abbas Torki S, Aminnezhad Kavkani B et al., 2024, systematic review
  3. Effect of prebiotics, probiotics, synbiotics on depression: results from a meta-analysis — Zhang Q, Chen B, Zhang J et al., 2023, meta-analysis
  4. A systematic review of the effects of probiotics on depression and anxiety: an alternative therapy? — Minayo MS, Miranda I, Telhado RS, 2021, systematic review
  5. Prebiotics and probiotics for depression and anxiety: A systematic review and meta-analysis of controlled clinical trials — Liu RT, Walsh RFL, Sheehan AE, 2019, meta-analysis
  6. Effect of Probiotics on Depression: A Systematic Review and Meta-Analysis of Randomized Controlled Trials — Huang R, Wang K, Hu J, 2016, meta-analysis
  7. Gut microbiome differences in children with Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorder and effects of probiotic supplementation: A randomized controlled trial — Novau-Ferré N, Papandreou C, Rojo-Marticella M et al., 2025, randomised controlled trial
  8. Metabolome-associated psychological comorbidities improvement in irritable bowel syndrome patients receiving a probiotic — Martin FP, Cominetti O, Berger B et al., 2024, randomised controlled trial
  9. Effects of dietary fibers or probiotics on functional constipation symptoms and roles of gut microbiota: a double-blinded randomized placebo trial — Lai H, Li Y, He Y et al., 2023, randomised controlled trial
  10. Psychobiotic Lactobacillus plantarum JYLP-326 relieves anxiety, depression, and insomnia symptoms in test anxious college via modulating the gut microbiota and its metabolism — Zhu R, Fang Y, Li H et al., 2023, randomised controlled trial
How much research is there on probiotics mood?
14 publications are indexed here, of which 8 are trials and 6 are syntheses.
Does more research mean a stronger conclusion?
No. Composition matters more than volume — five randomised trials support a claim far better than fifty commentaries, and citation counts do not distinguish between them.
How current is this?
The most recent paper indexed here is from 2025. The set is refreshed weekly from PubMed and Crossref.
Why does this page not tell me the answer?
Because summarising a literature into a conclusion requires reading it, and doing that automatically is how confident nonsense gets published. This page tells you how much weight a conclusion could bear; the articles on this site do the interpreting.

References

Every citation below links to the original peer-reviewed record on PubMed or via DOI. Nothing here is a substitute for medical advice.

  1. Effects of Prebiotics and Probiotics on Symptoms of Depression and Anxiety in Clinically Diagnosed Samples: Systematic Review and Meta-analysis of Randomized Controlled Trials Asad A, Kirk M, Zhu S, et al. · Nutrition reviews · 2025 · Meta-analysis DOIPubMed 39731509Full text
  2. A systematic review of the beneficial effects of prebiotics, probiotics, and synbiotics on ADHD Allahyari P, Abbas Torki S, Aminnezhad Kavkani B, et al. · Neuropsychopharmacology reports · 2024 · Systematic review DOIPubMed 38623929Full text
  3. Effect of prebiotics, probiotics, synbiotics on depression: results from a meta-analysis Zhang Q, Chen B, Zhang J, et al. · BMC psychiatry · 2023 · Meta-analysis DOIPubMed 37386630Full text
  4. A systematic review of the effects of probiotics on depression and anxiety: an alternative therapy? Minayo MS, Miranda I, Telhado RS · Ciencia & saude coletiva · 2021 · Systematic review DOIPubMed 34586262
  5. Prebiotics and probiotics for depression and anxiety: A systematic review and meta-analysis of controlled clinical trials Liu RT, Walsh RFL, Sheehan AE · Neuroscience and biobehavioral reviews · 2019 · Meta-analysis DOIPubMed 31004628Full text
  6. Effect of Probiotics on Depression: A Systematic Review and Meta-Analysis of Randomized Controlled Trials Huang R, Wang K, Hu J · Nutrients · 2016 · Meta-analysis DOIPubMed 27509521Full text
  7. Gut microbiome differences in children with Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorder and effects of probiotic supplementation: A randomized controlled trial Novau-Ferré N, Papandreou C, Rojo-Marticella M, et al. · Research in developmental disabilities · 2025 · Randomised controlled trial DOIPubMed 40184961
  8. Metabolome-associated psychological comorbidities improvement in irritable bowel syndrome patients receiving a probiotic Martin FP, Cominetti O, Berger B, et al. · Gut microbes · 2024 · Randomised controlled trial DOIPubMed 38717445Full text
  9. Acceptability, Tolerability, and Estimates of Putative Treatment Effects of Probiotics as Adjunctive Treatment in Patients With Depression: A Randomized Clinical Trial Nikolova VL, Cleare AJ, Young AH, et al. · JAMA psychiatry · 2023 · Randomised controlled trial DOIPubMed 37314797Full text
  10. Effects of dietary fibers or probiotics on functional constipation symptoms and roles of gut microbiota: a double-blinded randomized placebo trial Lai H, Li Y, He Y, et al. · Gut microbes · 2023 · Randomised controlled trial DOIPubMed 37078654Full text
  11. Psychobiotic Lactobacillus plantarum JYLP-326 relieves anxiety, depression, and insomnia symptoms in test anxious college via modulating the gut microbiota and its metabolism Zhu R, Fang Y, Li H, et al. · Frontiers in immunology · 2023 · Randomised controlled trial DOIPubMed 37033942Full text
  12. Bifidobacterium breve CCFM1025 attenuates major depression disorder via regulating gut microbiome and tryptophan metabolism: A randomized clinical trial Tian P, Chen Y, Zhu H, et al. · Brain, behavior, and immunity · 2022 · Randomised controlled trial DOIPubMed 34875345
  13. Clinical, gut microbial and neural effects of a probiotic add-on therapy in depressed patients: a randomized controlled trial Schaub AC, Schneider E, Vazquez-Castellanos JF, et al. · Translational psychiatry · 2022 · Randomised controlled trial DOIPubMed 35654766Full text
  14. Probiotic Supplementation Improves Cognitive Function and Mood with Changes in Gut Microbiota in Community-Dwelling Older Adults: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial Kim CS, Cha L, Sim M, et al. · The journals of gerontology. Series A, Biological sciences and medical sciences · 2021 · Randomised controlled trial DOIPubMed 32300799Full text