Prebiotic Fiber (Inulin/FOS)

1 study · 1 supporting · 0 against

Inulin and FOS are fermented by colonic bacteria into short-chain fatty acids and increase stool bulk and water content, which raises stool frequency and softens stool.

Dose: 12–20 g

Tested as: ≥12 g/day native chicory inulin (the EFSA-authorised threshold) or 3–20 g/day fructo-oligosaccharides (FOS), for 1–14 weeks

2 studies · 2 supporting · 0 against

Short-chain fatty acids produced by fermentation may inhibit hepatic cholesterol synthesis and increase bile acid excretion, lowering circulating LDL.

Dose: 10–30 g

Tested as: 10–30 g/day inulin-type fructans (median ~10 g/day), for 4–36 weeks

1 study · 1 supporting · 0 against

Fermentation byproducts and increased release of satiety hormones (GLP-1, PYY) are proposed to modestly reduce appetite and calorie intake.

Dose: 3–30 g

Tested as: 3–30 g/day inulin-type fructans (median 10 g/day), median 12 weeks

1 study · 1 supporting · 0 against

Short-chain fatty acids and improved gut-barrier integrity are proposed to reduce low-grade systemic inflammation by limiting bacterial endotoxin leakage into the bloodstream.

Dose: 5–20 g

Tested as: 5–20 g/day inulin-type fructans, several weeks to months

2 studies · 0 supporting · 2 against

How it was tested: Bloating and flatulence intensity increased at 5.0 g and 7.5 g/day agave inulin doses versus control, though composite GI-intolerance scores remained low.

Rapid fermentation of inulin/FOS by colonic bacteria produces gas (CO2, H2, methane) as a direct byproduct — the same fermentation that improves stool frequency is what causes gas.

Dose: 5–15 g

Tested as: 5–20 g/day inulin or FOS — the same doses shown to improve bowel regularity

2 studies · 0 supporting · 1 against

How it was tested: Pooled analysis of 5 trials/6 arms found no significant overall effect on systolic BP (-5.83 mmHg, p=0.086) or diastolic BP (-2.62 mmHg, p=0.147); low quality of included studies.

Short-chain fatty acids from fermentation may activate blood-pressure-regulating receptors in blood vessels and kidneys, promoting vasodilation — a mechanism shown in animal and small human studies, not established at scale.

Dose: 10–15 g

Tested as: 10–15 g/day inulin, from 3 weeks to several months