Compound or practice · Nutrition
Inulin / FOS (Prebiotics)
Fermentable fibers that feed beneficial bacteria and short-chain-fatty-acid production — real but gassy, and rough on sensitive guts.
- Overall grade
- Grade C
- Last revised
- 2
- graded outcomes
- 0
- references listed
A structured monograph in Prometheus's bundled library. Its grades are the monograph's own reading of the evidence, not a peer-reviewed review.
1 at grade B · 1 at grade C — 2 graded rows
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Bifidobacteria / SCFAEvidence grade B
Reliable microbiome shift
Moderatehigh
- IBS symptomsEvidence grade C
Often worsens FODMAP-sensitive IBS
Unclearlow
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Thin evidence: IBS symptoms (grade C).
The evidence in words
What it is
Inulin and fructooligosaccharides are prebiotic fibers (from chicory, onions, etc.) that selectively feed beneficial gut bacteria.
How it works
Colonic bacteria ferment them into short-chain fatty acids (notably butyrate) that nourish the gut lining and shift the microbiome.
What the evidence shows
They reliably increase Bifidobacteria and SCFA production and can improve mineral absorption and modest metabolic markers. Symptom benefits are inconsistent, and they commonly cause gas and bloating — and are high-FODMAP, so they worsen many IBS cases rather than helping.
How to use it
Start very low (2–5 g/day) and titrate; avoid if you have FODMAP-sensitive IBS.
Safety & interactions
Safe but frequently gas-producing; poorly tolerated in IBS.
Bottom line
Genuine prebiotic action, but the bloating is real and it's the wrong fiber for FODMAP-sensitive guts. Start low or choose psyllium instead.
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Titrate
- Start 2–5 g/day; avoid in FODMAP-sensitive IBS.
Related reading
Entries that share this one's tags or conditions.
- Beta-GlucansTwo different molecules under one name: oat beta-glucan reliably lowers LDL; yeast/mushroom beta-glucan modulates immunity.Evidence grade B
- Inulin / FOS (Prebiotics) for Bifidobacteria / SCFAEvidence grade B — Reliable microbiome shiftEvidence grade B
- Inulin / FOS (Prebiotics) for IBS symptomsEvidence grade C — Often worsens FODMAP-sensitive IBSEvidence grade C
- Inulin / FOS (Prebiotics): dosage and how to take itStart 2–5 g/day; avoid in FODMAP-sensitive IBS.Evidence grade C
Sources
This entry lists no references of its own.
Last revised . A grade is this entry's reading of the evidence, not medical advice.