Prebiotics (Inulin, FOS)

In brief

Prebiotics are fermentable fibers (such as inulin and fructo-oligosaccharides or FOS) that our enzymes cannot digest, but beneficial gut bacteria use as an energy source.
👉 They promote the growth of bifidobacteria and help maintain a healthy intestinal balance.

🟢 What it does (main evidence)

• Bowel regularity: moderate improvement in regularity, especially in people with low fiber intake.
• Microbiome: increases in bifidobacteria and lactobacilli; enhanced production of short-chain fatty acids (SCFAs) that benefit the intestinal lining.
• Metabolic health: preliminary evidence of positive effects on blood sugar and lipids via microbiome modulation.

🟡 What’s unclear

• Effects on bloating and abdominal comfort depend strongly on dose and individual tolerance.
• Minimal direct effect on weight or food intolerances.
• Effectiveness varies depending on fiber type (inulin vs FOS vs GOS).

🔴 What it doesn’t do

• Does not replace probiotics (does not supply live bacteria).
• Does not act immediately — requires several days to weeks for a stable effect.
• No proven role in “detox” or weight-loss regimens.

Dosage & usage (non-prescriptive)

• 2 to 10 g/day, gradually increased (+1 g every 3–4 days).
• Can be mixed into water, yogurt, or smoothies.
• Ideally taken with breakfast or a main meal.
• For many, the optimal tolerance is around 5 g/day.

Safety

• Generally very well tolerated.
• Gas and mild discomfort usually decrease after a few days of adaptation.
• Caution in IBS (Irritable Bowel Syndrome) — start at a very low dose.

Risks & interactions

• May increase gas; start low and increase gradually.
• May alter absorption of certain medications if taken together (separate by 2 hours).

Quality tips

• Check the exact inulin/FOS content (g per serving).
• Avoid powders with excessive sweeteners or additives.
• Combine with probiotics if desired for a synergistic effect.
• Store in a dry place at room temperature.

Sources

• Examine.com — Inulin Overview
• NIH/ODS — Dietary Fibers & Gut Health
• Health Canada — Guidance on Prebiotic Products