Gut Brain Evidence

Evidence map

Microbiome diversity: what the evidence base looks like

14 publications, 7 of them trials and 5 syntheses. This page describes the shape of that literature rather than summarising its conclusions.

Updated 4 min read 14 citations

Compound light microscope with objective turret and stage, standing on a bench
Ajay Kumar Chaurasiya · CC BY-SA 4.0 · Wikimedia Commons
What the evidence on microbiome diversity is made of Of 14 publications on this topic, the breakdown by study type: 5 meta-analysis, 7 randomised trial, 2 review. 572meta-analysis (5)randomised trial (7)review (2)
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 microbiome diversity literature was published Publication years for the 14 papers on this topic, grouped into bands from before 2015 through to 2023 onwards. 2023 onwards7 papers2020-20224 papers2015-20192 papersBefore 20151 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.

Pale rubbery kombucha cultures stacked in overlapping layers on a surface
The floating mat is a symbiotic culture of bacteria and yeast, not a mushroom. Hexatekin · CC BY-SA 4.0 · 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. The Correlation Between Carbohydrate Loading Diet and Gut Microbiome: A Systematic Review — El-Kholy O, Nichols L, Elsayed AAR et al., 2025, systematic review
  2. Roles of the gut microbiome in weight management — Carmody RN, Bisanz JE, 2023, meta-analysis
  3. Probiotics for Alzheimer's Disease: A Systematic Review — Naomi R, Embong H, Othman F et al., 2021, systematic review
  4. Meta-analysis of fecal metagenomes reveals global microbial signatures that are specific for colorectal cancer — Wirbel J, Pyl PT, Kartal E et al., 2019, meta-analysis
  5. Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes — Clark A, Mach N, 2016, systematic review
  6. Mediterranean diet, gut microbiota, and cognitive decline in older adults with obesity/overweight and metabolic syndrome: a prospective cohort study — Ni J, Hernández-Cacho A, Nishi SK et al., 2025, randomised controlled trial
  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. Host-diet-gut microbiome interactions influence human energy balance: a randomized clinical trial — Corbin KD, Carnero EA, Dirks B et al., 2023, randomised controlled trial
  9. Randomized Controlled-Feeding Study of Dietary Emulsifier Carboxymethylcellulose Reveals Detrimental Impacts on the Gut Microbiota and Metabolome — Chassaing B, Compher C, Bonhomme B et al., 2022, randomised controlled trial
  10. Gut-microbiota-targeted diets modulate human immune status — Wastyk HC, Fragiadakis GK, Perelman D et al., 2021, randomised controlled trial
How much research is there on microbiome diversity?
14 publications are indexed here, of which 7 are trials and 5 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. The Correlation Between Carbohydrate Loading Diet and Gut Microbiome: A Systematic Review El-Kholy O, Nichols L, Elsayed AAR, et al. · MicrobiologyOpen · 2025 · Systematic review DOIPubMed 40765268Full text
  2. Roles of the gut microbiome in weight management Carmody RN, Bisanz JE · Nature reviews. Microbiology · 2023 · Meta-analysis DOIPubMed 37138047Full text
  3. Probiotics for Alzheimer's Disease: A Systematic Review Naomi R, Embong H, Othman F, et al. · Nutrients · 2021 · Systematic review DOIPubMed 35010895Full text
  4. Meta-analysis of fecal metagenomes reveals global microbial signatures that are specific for colorectal cancer Wirbel J, Pyl PT, Kartal E, et al. · Nature medicine · 2019 · Meta-analysis DOIPubMed 30936547Full text
  5. Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes Clark A, Mach N · Journal of the International Society of Sports Nutrition · 2016 · Systematic review DOIPubMed 27924137Full text
  6. 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
  7. Mediterranean diet, gut microbiota, and cognitive decline in older adults with obesity/overweight and metabolic syndrome: a prospective cohort study Ni J, Hernández-Cacho A, Nishi SK, et al. · BMC medicine · 2025 · Randomised controlled trial DOIPubMed 41327300Full text
  8. Host-diet-gut microbiome interactions influence human energy balance: a randomized clinical trial Corbin KD, Carnero EA, Dirks B, et al. · Nature communications · 2023 · Randomised controlled trial DOIPubMed 37258525Full text
  9. Randomized Controlled-Feeding Study of Dietary Emulsifier Carboxymethylcellulose Reveals Detrimental Impacts on the Gut Microbiota and Metabolome Chassaing B, Compher C, Bonhomme B, et al. · Gastroenterology · 2022 · Randomised controlled trial DOIPubMed 34774538Full text
  10. Gut-microbiota-targeted diets modulate human immune status Wastyk HC, Fragiadakis GK, Perelman D, et al. · Cell · 2021 · Randomised controlled trial DOIPubMed 34256014Full text
  11. Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries Ghosh TS, Rampelli S, Jeffery IB, et al. · Gut · 2020 · Randomised controlled trial DOIPubMed 32066625Full text
  12. The interplay between diet and the gut microbiome: implications for health and disease Ross FC, Patangia D, Grimaud G, et al. · Nature reviews. Microbiology · 2024 · Review DOIPubMed 39009882
  13. The human gut microbiome and aging Bradley E, Haran J · Gut microbes · 2024 · Review DOIPubMed 38831607Full text
  14. Diet rapidly and reproducibly alters the human gut microbiome David LA, Maurice CF, Carmody RN, et al. · Nature · 2014 · Clinical trial DOIPubMed 24336217Full text