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Galacto-oligosaccharides (GOS)

Gut health · Prebiotic · Immunity

Tier 2 — Promising

What it is

Short-chain prebiotic fibres naturally present in small amounts in dairy milk. GOS selectively feeds Bifidobacterium and Lactobacillus species with stronger selectivity than most other prebiotics. Multiple RCTs demonstrate improvements in bowel frequency, stool consistency, gut transit time, and immune modulation. Well-tolerated up to 15 g/day with minimal bloating compared to inulin or FOS. Particularly well-studied in infants and the elderly, with growing adult data for gut-immune support.

Efficacy

3/5

Safety

5/5

Research

3/5

Onset

3/5

Cost

4/5

Drug-int.

4/5

Dose

5–15 g/day dissolved in water or milk

Time of day & tips

Start at 2–3 g/day and increase over 2 weeks to avoid bloating; highly synergistic with probiotic supplementation

Sensitive populations: This supplement's evidence base touches pregnancy, pediatric, or other sensitive populations. Confirm any change with your healthcare provider before use.

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