# Gut microbiome diversity and composition

Source: https://onco.cc/terms/gut-microbiome-diversity/  
OnCo record `gut-microbiome-diversity` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

How many different kinds of bacteria live in the gut and which ones dominate. Higher diversity and certain species are linked with better immunotherapy response; antibiotics and poor diet reduce both.

## Summary

Alpha diversity (within a person) and specific taxa (Faecalibacterium, Ruminococcaceae, Akkermansia muciniphila, Bifidobacterium) associate with checkpoint-inhibitor response, though the taxa differ between cohorts and countries, and no microbiome test is validated for clinical use. Diet (fibre), antibiotics, proton-pump inhibitors and probiotics are the main modifiable determinants. Causality is supported by mouse FMT experiments and by early human FMT trials.

## Fields

- Kind: Term
- Last checked: 2026-09-08
- Also known as: Alpha diversity; Shannon index; Dysbiosis

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Gut_microbiota
- Wikipedia: https://en.wikipedia.org/wiki/Gut_microbiota

## Connected records

- technologies: [Dietary fibre and the gut microbiome for immunotherapy response](https://onco.cc/technologies/dietary-fibre-microbiome-io/), [Faecal microbiota transplantation for PD-1 non-responders](https://onco.cc/technologies/fmt-checkpoint-nonresponders/), [Microbiome modulation to unlock immunotherapy](https://onco.cc/technologies/microbiome-modulation-io/), [Probiotics, antibiotics and stewardship around immunotherapy](https://onco.cc/technologies/probiotics-antibiotic-stewardship-io/)
- pathways: [Microbiome-tumour interactions](https://onco.cc/pathways/microbiome-tumour/)
- terms: [Hallmark (2022): polymorphic microbiomes](https://onco.cc/terms/polymorphic-microbiomes/)
- bottlenecks: [Biomarkers are not validated or standardised](https://onco.cc/bottlenecks/b-biomarker-validation/), [No one can predict who responds to immunotherapy](https://onco.cc/bottlenecks/b-immunotherapy-response/)
- key papers: [Geographic and age variations in mutational processes in colorectal cancer](https://onco.cc/key-papers/paper-diaz-gay-colibactin-geographic-age-mutational-processes-nature-2025/)
- roadmaps: [Colorectal cancer roadmap: from the adenoma-carcinoma sequence and the first screening trials to total mesorectal excision, oxaliplatin, RAS testing, immunotherapy for mismatch repair-deficient disease, ctDNA-guided treatment and organ preservation](https://onco.cc/roadmaps/colorectal-roadmap/), [Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment](https://onco.cc/roadmaps/nutrition-lifestyle-roadmap/)
- ideas: [Capture diet, fibre and antibiotic exposure in every immunotherapy pivotal trial](https://onco.cc/ideas/idea-nl-diet-covariates-io-trials/), [Controlled feeding trials to separate ultra-processing from calories](https://onco.cc/ideas/idea-nl-upf-controlled-feeding-trial/), [Find out what is driving early-onset bowel cancer, starting with colibactin, before extending screening any further](https://onco.cc/ideas/idea-crc-early-onset-cause-hunt/)
- trials: [FMT plus pembrolizumab in anti-PD-1-refractory melanoma (Pittsburgh)](https://onco.cc/trials/fmt-pd1-refractory-melanoma-pitt/), [MIMic-01: healthy-donor FMT plus anti-PD-1, first-line melanoma](https://onco.cc/trials/mimic-01/)

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