Glucomannan

Konjac glucomannan · Amorphophallus konjac

Snapshot

Indications	Contraindications
Functional constipation^{1, 2} Low-density lipoprotein cholesterol^{3, 4} Body weight in overweight or obesity⁵ Fasting glucose^{4, 6}	Difficulty swallowing⁷ Pregnancy or nursing⁸

Glucomannan is a viscous, gel-forming soluble fiber extracted from the tubers of Amorphophallus konjac, which coats and bulks the gut contents⁹. The typical patient is an adult with raised cholesterol or overweight. Patients with impaired glucose metabolism benefited less in pooled trials⁴.

Weight evidence is split: one review found no significant difference from placebo, while a later review found a small, statistically significant loss below its clinical significance threshold^{10, 11}. A 2023 randomized, placebo-controlled trial during energy restriction found a blend of glucomannan, inulin, psyllium, and apple fibre most effective at lowering body weight and C-reactive protein¹². Products listing glucomannan are mostly capsules and powders; see Form comparison.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

58 sources, 46 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources