Prebiotics (Inulin / GOS / PHGG)
The food that feeds your gut bacteria. The other half of the probiotic equation — and arguably more important than the probiotic itself.
Strong for shifting gut bacterial composition, increasing short-chain fatty acid production, and supporting calcium absorption. Moderate for IBS symptom relief (PHGG specifically), mineral absorption, modest immune support, and metabolic markers. Effects: 4–12 weeks.
Prebiotics are fibres that humans can't digest but gut bacteria can — and the bacteria ferment them into short-chain fatty acids (butyrate, propionate, acetate) that feed your colon cells, modulate immunity, and support metabolic health. Different prebiotics feed different bacteria. Inulin and FOS feed Bifidobacteria. GOS feeds both Bifidobacteria and Lactobacilli. PHGG (Sunfiber) is the gentlest and best-tolerated. Beta-glucans feed Akkermansia. The microbiome is a garden — probiotics plant seeds, but prebiotics are the soil and water.
- Form
- Inulin / FOS (chicory root, Jerusalem artichoke) — broad bifidogenic effect. GOS (Bimuno) — clinically studied, mild side effects. PHGG / Sunfiber — partially hydrolysed guar gum, the gentlest. Resistant starch (RS2 / RS3 / RS4) — feeds butyrate-producers. Acacia fibre.
- Dose
- Start with 3–5 g/day and titrate up to 10–20 g/day as tolerated. Going too fast causes GI symptoms.
- Timing
- With or without food. Spread across the day for higher doses.
- Schedule
- Daily, ongoing. Effects build over weeks.
- Side effects
- Gas, bloating, abdominal discomfort — especially with inulin and FOS in sensitive individuals or with SIBO. Start very small and titrate. PHGG is the gentlest option.
- Interactions
- Generally clean. Inulin and similar may modestly alter mineral absorption (mostly improving it via short-chain fatty acid effects on colonocytes).
- Contraindications
- SIBO (small intestinal bacterial overgrowth) — prebiotics feed the bacteria in the wrong place; can dramatically worsen symptoms. Active IBD flare. Severe FODMAP intolerance.
- Lab markers
- Stool microbiome analysis. Subjective tracking.
- Food sources
- Garlic, onion, leeks, chicory root, Jerusalem artichoke, dandelion greens, asparagus, bananas (slightly green), oats, barley, legumes, cooked-and-cooled potatoes / rice (resistant starch). A vegetable-and-legume-heavy diet delivers ~10–20 g/day.
Pairs with
Probiotics (synbiotic effect — feed what you plant). Polyphenols (curcumin, resveratrol, green tea — fermentation in gut releases more bioactivity). Fermented foods (broad microbiome support).
within Probiotics & gut