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GUT & DIGESTIVE

Glucomannan (Konjac Fiber)

Appetite · cholesterol · blood sugar

STRONG EVIDENCEVEGANREAD THE RESEARCH
Written to our editorial standards · reviewed against published research· Updated 5 Jun 2026
Last reviewed: May 30, 2026
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Glucomannan: Appetite · cholesterol · blood sugar. A highly viscous soluble fiber with strong evidence for fullness, cholesterol, and post-meal blood sugar. Standard dose 1,000 mg before meals, taken in the midday, about $12/month. Evidence rating: strong evidence.

Where to buy

NOWFOODSGlucomannan180 VEG CAPSDIETARY SUPP.
RECOMMENDED
NOW Foods, Glucomannan
1,000 mg before meals · Midday · ~$12/month

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All product options

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Glucomannan
NOW Foods
180 veg caps · $12 · ★ 4.6
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Glucomannan
Nutricost
240 capsules · $16 · ★ 4.6
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DOUBLEWOODGlucomannan180 CAPSULESDIETARY SUPP.PREMIUM
Glucomannan
Double Wood
180 capsules · $18 · ★ 4.5
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SOURCENATURALSGlucomannan120 TABLETSDIETARY SUPP.PREMIUM
Glucomannan
Source Naturals
120 tablets · $14 · ★ 4.5
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What is Glucomannan?

Glucomannan is a soluble fiber from the konjac root that absorbs many times its weight in water to form a thick gel. That viscosity is the mechanism: it slows stomach emptying to increase fullness, blunts the post-meal rise in blood sugar, and binds bile to lower LDL cholesterol, all backed by an EU-approved health claim for cholesterol and reasonable trial support for satiety and weight. Take 1 g with a large glass of water before meals, and never take it dry or right before lying down, since it can swell in the throat or esophagus. Start low to let the gut adjust.

WHY IT MATTERS

A highly viscous soluble fiber with strong evidence for fullness, cholesterol, and post-meal blood sugar.

Natural food sources

Where possible, get Glucomannan from whole foods first. Common dietary sources include:

Konjac rootShirataki noodles

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Common questions

What is Glucomannan?
Glucomannan is a soluble fiber from the konjac root that absorbs many times its weight in water to form a thick gel. That viscosity is the mechanism: it slows stomach emptying to increase fullness, blunts the post-meal rise in blood sugar, and binds bile to lower LDL cholesterol, all backed by an EU-approved health claim for cholesterol and reasonable trial support for satiety and weight. Take 1 g with a large glass of water before meals, and never take it dry or right before lying down, since it can swell in the throat or esophagus. Start low to let the gut adjust.
What is Glucomannan used for?
Appetite · cholesterol · blood sugar. A highly viscous soluble fiber with strong evidence for fullness, cholesterol, and post-meal blood sugar.
What is the standard dose of Glucomannan?
1,000 mg before meals, typically taken in the midday. Approximate cost is $12 per month.
Who should avoid Glucomannan?
Use extra caution, and speak to a clinician first, if you are pregnant or nursing.
How strong is the evidence for Glucomannan?
Strong evidence for its primary uses. See the full study list on the research page.

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