Glucomannan (Konjac Fiber · KGM)

CAS No.	37220-17-0
Class	Polysaccharide · Soluble dietary fiber
Source	Amorphophallus konjac — tuber
Claim strength	High — EFSA approved health claims
Buy from Herbuno	Konjac Glucomannan 95% → · Konjac Flour →

Glucomannan is the water-soluble polysaccharide extracted from the konjac tuber — a chain of glucose and mannose units that forms one of the most viscous gels of any known dietary fiber when hydrated. A single gram dissolved in water produces a gel of remarkable viscosity, which underpins every documented physiological effect. It has been consumed as a food ingredient in East Asia for centuries; the purified extract is the standardised commercial form used in supplement and functional food applications.

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Glucomannan for Weight Management, Cholesterol & Blood Glucose — Clinical Evidence

How it works: Glucomannan forms a highly viscous gel in the stomach and small intestine that slows gastric emptying, reduces glucose absorption rate, traps bile acids for elimination, and extends satiety by maintaining gastric distension. The effects are mechanical — not systemic — which explains consistent results across individuals regardless of metabolic variation.

Weight management: Multiple RCTs document significant body weight reduction averaging 1.5–2.5 kg over 5–8 weeks versus placebo at 3g per day. The EFSA approved health claim reads: "Glucomannan in the context of an energy-restricted diet contributes to weight loss." This is one of the few approved weight management claims available for a botanical fiber ingredient in the EU regulatory framework.

Cholesterol management: LDL reduction of 10–16 mg/dL is consistently documented across trials at 3–4g per day. The mechanism is bile acid sequestration — glucomannan gel traps bile acids in the intestinal lumen and prevents their reabsorption, forcing hepatic conversion of cholesterol to replacement bile acids. EFSA approved claim: "Glucomannan contributes to maintenance of normal blood cholesterol levels."

Blood glucose support: Post-prandial glucose response is reduced by 20–30% when glucomannan is taken before a carbohydrate-containing meal. The mechanism is rate-of-absorption reduction — slowing glucose entry into the bloodstream rather than interfering with insulin pathways. Useful for glycaemic management formulations and diabetic-friendly functional food positioning.

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Glucomannan Dosage, Format & Formulator Specification

Standard dose: 3–4g per day in three divided doses taken before meals. At 500mg per capsule this requires 6 capsules daily — powder sachet format dissolved in 250ml water is typically the more compliant and commercially practical delivery format.

Label requirement — mandatory in regulated markets: Glucomannan swells rapidly on contact with moisture. The FDA and EFSA both require a minimum fluid intake instruction on the label — typically "take with at least 250ml of water." This is not optional copy. Undissolved powder presents an aspiration risk without adequate hydration.

Specification — two grades, different applications: Konjac Glucomannan 95% is the high-purity supplement grade for EFSA/FDA label claims. Konjac Flour is the food-grade option — lower purity, lower cost, appropriate for functional food fiber enrichment and konjac noodle manufacture. Confirm viscosity rating (cP) on the CoA — viscosity predicts physiological efficacy per gram more accurately than glucomannan percentage alone. Request viscosity specification at enquiry stage.

Pairs with: Psyllium husk (complementary fiber types for broader GI coverage), chromium picolinate (glycaemic management stacks), green tea extract (weight management formulations), inulin (prebiotic + satiety combination formats).

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Frequently Asked Questions — Glucomannan

What is glucomannan and where does it come from?
Glucomannan is a water-soluble dietary fiber extracted from the tuber of the konjac plant (Amorphophallus konjac), native to East and Southeast Asia. It is the primary active component of konjac flour and is available as a purified extract standardised to 90–95% glucomannan content for supplement applications.

What is the EFSA approved health claim for glucomannan?
EFSA has approved two health claims for glucomannan: (1) "Glucomannan in the context of an energy-restricted diet contributes to weight loss" — requires 1g per meal, three times daily; (2) "Glucomannan contributes to maintenance of normal blood cholesterol levels" — requires 4g per day. Both claims are listed under EU Regulation 432/2012.

What is the difference between konjac flour and glucomannan 95%?
Konjac flour is a milled whole konjac tuber product containing approximately 40–60% glucomannan alongside starch and other plant compounds. Glucomannan 95% is the purified extracted fiber fraction standardised to not less than 95% glucomannan content. The 95% grade is required for supplement label claims; konjac flour is appropriate for food applications where purity specification is less critical.

How should glucomannan be taken — capsule or powder?
Both formats work, but the capsule format requires a minimum of 250ml water per dose and a clear label instruction. Powder sachet dissolved in water before meals is typically better tolerated and has higher compliance in clinical practice. The EFSA dose of 1g per meal (three times daily) is achievable in either format.

Is glucomannan safe for long-term use?
Glucomannan has a well-established safety profile — it has been consumed as a food ingredient in Japan and China for centuries and has GRAS status in the United States. The primary safety consideration is the aspiration risk from undissolved powder without adequate water, which is a labelling and instruction compliance issue rather than a compound toxicity concern. No significant adverse effects have been documented at clinical doses in long-term trials.

 

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