⚠️
Major drug interaction. This ingredient has clinically significant drug interactions. See Drug Interactions below before use.
Upper Safe Limit
3g/day for EU health claim (taken in 3x1g doses before meals with water)
PubMed Studies
68
PubChem CID
About
Glucomannan is a soluble dietary fibre from konjac root with the strongest evidence of any supplement for weight loss. EU approved health claim: glucomannan contributes to weight loss as part of an energy-restricted diet (3g/day). Also lowers cholesterol and blood sugar.
How it works (mechanism of action)
Forms highly viscous gel in stomach, dramatically slowing gastric emptying and creating satiety. Reduces postprandial glucose by slowing carbohydrate absorption. Prebiotic effect feeds Bifidobacterium. EFSA approved 3g/day for weight management claim.
👥 Safety by Population
🚫 Contraindications & Warnings
MUST be taken with large amounts of water — oesophageal obstruction risk if taken without adequate fluid. Take 30 minutes before meals. Drug absorption interference — separate all medications by 2+ hours.
💊 Drug Interactions (6)
🔴 All oral medications
MajorVarious
Management: ALWAYS take glucomannan at least 2 hours before or after any oral medication. Never take with medications.
🟡 Metformin / Glipizide
ModerateAntidiabetics
Management: Monitor blood glucose closely. May need antidiabetic dose reduction.
🟡 Levothyroxine
ModerateThyroid medications
Management: Separate by minimum 4 hours. Take levothyroxine first.
🟡 Oral medications (general)
ModerateGeneral medications
Management: Take all oral medications 1 hour before or 4 hours after glucomannan.
⚪ Warfarin
MinorAnticoagulants
Management: Take warfarin at least 1 hour before or 4 hours after glucomannan.
⚪ Statins
MinorStatins
Management: Separate by 2 hours. May modestly reduce statin absorption.
🇪🇺 EU Health Claims Status
Art.13(1)
✓ AuthorisedThe claim may be used only for food which provides a daily intake of 4 g of glucomannan. In order to bear the claim information shall be given to the consumer that the beneficial effect is obtained with a daily intake of 4 g of glucomannan. Warning of choking to be given for people with swallowing difficulties or when ingesting with inadequate fluid intake - advice on taking with plenty of water to ensure substance reaches stomach.
Regulation EU 1924/2006 · ART13 1
Art.13(1)
✓ AuthorisedThe claim may be used only for food which contains 1 g of glucomannan per quantified portion. In order to bear the claim information shall be given to the consumer that the beneficial effect is obtained with a daily intake of 3 g of glucomannan in three doses of 1 g each, together with 1-2 glasses of water, before meals and in the context of an energy-restricted diet. Warning of choking to be given for people with swallowing difficulties or when ingesting with inadequate fluid intake - advice on taking with plenty of water to ensure substance reaches stomach.
Regulation EU 1924/2006 · ART13 1
Art.13(1)
✓ AuthorisedNon-compliance with the Regulation because on the basis of the scientific evidence assessed, this claimed effect for this food has not been substantiated.
Regulation EU 1924/2006 · ART13 1
Art.13(1)
✓ AuthorisedNon-compliance with the Regulation because on the basis of the scientific evidence assessed, this claimed effect for this food has not been substantiated.
Regulation EU 1924/2006 · ART13 1
Art.13(1)
✓ AuthorisedNon-compliance with the Regulation because on the basis of the scientific evidence assessed, this claimed effect for this food has not been substantiated.
Regulation EU 1924/2006 · ART13 1
Art.13(1)
✓ AuthorisedNon-compliance with the Regulation because on the basis of the scientific evidence assessed, this claimed effect for this food has not been substantiated.
Regulation EU 1924/2006 · ART13 1
Art.13(1)
✓ AuthorisedNon-compliance with the Regulation because on the basis of the scientific evidence assessed, this claimed effect for this food has not been substantiated.
Regulation EU 1924/2006 · ART13 1
⚠️ Adverse Effects (1)
Oesophageal obstruction
rare but serious without adequate water Severe
Gastrointestinal system
MUST be taken with large amounts of water. Tablets/powder can swell in throat if swallowed dry.
🏷️ Other Names
Konjac glucomannan
References (2)
- National Institutes of Health. Zinc: Fact Sheet for Health Professionals. 2022. Available from: https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/ Reference Source ↗
- EFSA. EFSA J. 2014;12(10):3844. Regulatory document DOI ↗
Evidence grades: SR = Systematic review / meta-analysis (highest) · RCT = Randomized controlled trial · Reg = Regulatory/official guidance