Inulin (Prebiotic Fiber)
Supplements · Digestive Health · Supplement, Typed Supps
Not food for you — food for the bacteria living in your gut.
Stage by stage
- Intake (Powder): Humans lack the enzymes to digest it directly.
- Stomach & small intestine (Passes through undigested): Passes through largely intact, unlike most carbohydrates.
- Colon (Reaches intact): Reaches the colon still intact.
- Gut bacteria (Fermented as fuel): Fermented by gut bacteria, which use it as fuel and produce beneficial byproducts.
What the evidence supports
- Acting as a prebiotic that feeds beneficial gut bacteria — moderate evidence. Inulin is a well-characterised fermentable fibre that reliably increases Bifidobacteria; the microbial shift is consistently shown, even if downstream health effects are less certain.
- Easing mild constipation and improving stool regularity — limited evidence. Some trials show improved stool frequency and consistency, particularly in people with low fibre intake, but effects are modest and not universal.
- Enhancing calcium (and magnesium) absorption — limited evidence. Studies, mainly in adolescents and postmenopausal women at higher doses (around 8 g/day or more), suggest improved mineral absorption; the evidence is limited and population-specific.
Typical dose
Around 3–10 g/day, started at 2–3 g and titrated up over weeks
Upper limit: No formal UL; doses above about 10–15 g/day commonly cause gas and bloating
Timing
Start with small amounts — commonly causes gas and bloating at higher doses initially.
Time to effect
- Days–wks: Digestive changes, then any broader reported gut-microbiome effect.
Common myth
“More prebiotic fibre is always better for gut health.” In reality: Ramping up too quickly is one of the most common reasons people quit — bloating and gas are common until gut bacteria adjust.
Food sources
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