---
id:"kb-2026-00425"
title:"Gut Microbiome"
schema_type:"TechArticle"
category:"health"
language:"en"
confidence:"high"
last_verified:"2026-05-22"
generation_method:"ai_assisted"
ai_models:["claude-opus"]
derived_from_human_seed:true
primary_sources:
  - title:"I Contain Multitudes (Ed Yong)"
    type:"book"
    year:2016
    url:"https://www.harpercollins.com/products/i-contain-multitudes-ed-yong"
    institution:"Ecco"
secondary_sources:
  - title: "MDN Web Docs — HTTP"
    type: "documentation"
    year: 2026
    url: "https://developer.mozilla.org/en-US/docs/Web/HTTP"
    institution: "Mozilla"
completeness: 0.88
ai_citations:
  last_citation_check:"2026-05-22"
---

## TL;DR

The gut microbiome is the ecosystem of ~39 trillion bacteria in the human digestive tract — roughly equal to human cells. It influences digestion, immunity, mental health (gut-brain axis), metabolism, and disease risk. Shaped by diet (fiber feeds beneficial bacteria), antibiotics (disrupt), birth method (vaginal vs. C-section).

## Core Explanation

Diversity: more diverse microbiome = generally healthier. Prebiotics: fiber that feeds beneficial bacteria (garlic, onions, bananas). Probiotics: live bacteria (yogurt, kimchi, supplements). Fecal microbiota transplant (FMT): transferring stool from healthy donor — 90%+ effective for C. difficile infections. Gut-brain axis: gut produces 95% of body's serotonin. 'You are what you eat' — your microbiome reflects your diet.

## Further Reading

- [I Contain Multitudes (Ed Yong)](https://www.harpercollins.com/products/i-contain-multitudes-ed-yong)