Prebiotic Fiber (Inulin/FOS)

1 study · 1 supporting · 0 against

Feeds your gut bacteria and adds bulk and water to stool, which gets things moving.

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

What your gut bacteria make from it may slow cholesterol production in the liver.

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

Proposed to raise the fullness hormones your gut releases, so you eat a little less.

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

Proposed to seal the gut lining so less bacterial debris leaks into the blood.

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: Mild bloating was reported significantly more often as an adverse event on FOS versus placebo (OR 10.36, 95% CI 3.32-33.23).

Your gut bacteria ferment it — and gas is a direct byproduct of that same fermentation.

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: Pooling 5 trials, neither the top nor the bottom blood pressure number moved significantly.

What gut bacteria make from it may act on receptors that widen blood vessels.

Dose: 10–15 g

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