Home › Organ system
Organ systemMicrobiome
Also: gut flora, gut bacteria
Last scientific update: jun 2026
The microbiome is the collection of bacteria in your gut. They help digestion, train your immune system and make substances that influence your health.
Microbiome at a glance
WhatThe bacteria in your gut
ImportanceDigestion, immunity, possibly brainModerate
Feed itEat fibreStrong
HypeLarge, much unproven
A healthy gut flora matters, and eating fibre is the best-proven way to feed it; many other claims run ahead of the evidence.
39 studies5 answersupdated jun 2026
Evidence per claim
Fibre feeds your gut flora and helps long term
View evidence →Gut flora and mood or brain are linked
View evidence →A disturbed gut flora can weaken immunity
View evidence →Artificial sweeteners can affect the gut flora
View evidence →Practical use
For whom
Everyone; a varied, fibre-rich diet is the basis for a healthy gut flora.
Not for whom
Expensive microbiome tests and most probiotic pills add little for healthy people.
Usual dose
Eat varied and fibre-rich (vegetables, fruit, legumes, wholegrain); fermented food can help.
Key caveats
The science is still early; distrust firm claims and commercial tests.
What we know, and don't
Known
Fibre feeds the gut flora
A varied diet helps
Gut flora affects immunity and possibly brain
Not yet
What the ideal composition is
Whether probiotic pills add much
What a microbiome test means for you
Common misconceptions
"A microbiome test tells you what to eat."
Not shown. The science is not there yet; most tests are of little use.Moderate evidence
"Probiotic pills fix everything."
Incomplete. For healthy people the added value is limited; fibre does more.Moderate evidence
How Microbiome connects
Effects
Related news
Your immune system polices your gut bacteriaA synthetic gut microbiome could replace stool transplantsGut bacteria restore quality in aging eggs