Community metric · Functional group

Butyrate-producing bacteria

Community metric A functional guild that ferments fibre into butyrate — the main fuel for colon cells and a key anti-inflammatory signal.

Associated with these conditions

Type 2 diabetes Reduced

A broad reduction in butyrate producers is a recurring theme, plausibly linked to barrier and inflammation changes.

Moderate evidence

Metabolic syndrome Reduced

Fewer SCFA producers accompany the insulin-resistant, low-grade-inflammatory state.

Moderate evidence

What shifts it

Dietary fibre Raises it

Nutrient

Moderate evidence Well-established

Helps make

Short-chain fatty acidsneurotransmitter

The dominant chemical channel from gut to brain. Made when fibre-fermenters break down fibre, SCFAs feed the gut lining, calm microglia, tune the blood–brain barrier, and signal along the vagus nerve. Not a neurotransmitter in the textbook sense — but arguably the microbiome’s most important neuroactive output.

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