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Microbiome

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
178 studies30 answersupdated Nov 2026
Evidence per claim
Fibre feeds your gut flora and helps long term
View evidence →
Moderate
Gut flora and mood or brain are linked
View evidence →
Moderate
A disturbed gut flora can weaken immunity
View evidence →
Moderate
Artificial sweeteners can affect the gut flora
View evidence →
Preliminary
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.

In practice

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
Latest news on the microbiome
Ageing gut microbiome may contribute to bone loss through the immune system29 OctGut microbiome predicts inflammation better than age20 OctGut bacteria and exercise together shape muscle aging18 OctGut bacterium slows artery plaque in mice almost as well as a statin11 OctGut bacteria make stroke damage worse9 Oct
Heard on podcasts

What popular health podcasts claimed about the microbiome, checked against the research.

Dr. Mindy PelzDoes not hold up
“A wide variety of ingredients in a meal stimulates the microbiome to produce more of the hormone GLP-1.”
What the research says →
Max Lugavere · Dariush MozaffarianPartly
“Substances produced by gut bacteria in response to a healthy diet can prolong the satiating effect of GLP-1 in the brain.”
What the research says →
Thomas DeLauerPartly
“Eating an avocado every day increases the diversity of the gut microbiome and enriches Faecalibacterium, Lachnospira and Alistipes.”
What the research says →
Microbiome: what's new, and what holds up

We follow the latest research on the microbiome and listen to leading health podcasts, and we check what they claim. You'll get one email on Thursdays with what matters, and only when there's something new.

You can add more topics later, such as exercise or sleep.

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