Glucomanano, Glucomannane, Konjac Mannan.


Overview Information

Glucomannan is a dietary fiber. It is usually made from the root of the konjac plant. Glucommanan powder, capsules, and tablets are used as medicine.

Glucomannan is used by mouth for constipation, diabetes, and high cholesterol. Some people take glucomannan by mouth for high blood pressure, obesity, and other conditions. But there is no good scientific research to support these other uses of glucomannan.

In foods, glucomannan is used as a thickener or gelling agent. Glucommanan flour and powder are used in food.

How does it work?

Glucomannan might work in the stomach and intestines by absorbing water to form a bulky fiber which treats constipation. It may also slow the absorption of sugar and cholesterol from the gut, helping to control sugar levels in diabetes, and reducing cholesterol levels.


Uses & Effectiveness?

Possibly Effective for

  • Constipation. Taking glucomannan by mouth can relieve constipation in adults. It might also reduce constipation in children, but results are mixed.
  • Diabetes. Taking glucomannan by mouth seems to reduce cholesterol, blood sugar levels, and blood pressure in people with diabetes.
  • High cholesterol. Taking glucomannan by mouth seems to improve cholesterol levels in people with or without high cholesterol.

Insufficient Evidence for

  • Rapid gastric emptying (dumping syndrome). Dumping syndrome occurs when food moves from the stomach to the intestines too quickly. This can cause the body to release a large amount of insulin, which can cause low blood sugar. Some early research shows that taking glucomannan by mouth helps prevent blood sugar from becoming too low after eating in people at risk for this condition. However, not all research agrees.
  • A stomach condition called functional gastrointestinal disorder. Early research shows that taking glucomannan does not improve stomach pain, cramping, or bloating in children with this condition.
  • High blood pressure. Early research shows that glucomannan might improve blood pressure in people with high blood pressure.
  • Overactive thyroid (hyperthyroidism). Early research shows that adding glucomannan to treatment with methimazole and propranolol helps to reduce thyroid hormone levels in people with overactive thyroid.
  • Obesity. Some early research shows that taking glucomannan by mouth improves weight loss in overweight and obese adults and children. However, not all research agrees.
  • Other conditions.
More evidence is needed to rate glucomannan for these uses.

Side Effects

Side Effects & Safety

Glucomannan powder or flour is LIKELY SAFE when consumed as food. Glucomannan powder and capsules are POSSIBLY SAFE for most adults and children when used in medicinal amounts for up to 4 months. However, solid tablets containing glucomannan are POSSIBLY UNSAFE for adults and LIKELY UNSAFE for children. These can sometimes cause blockages of the throat or intestines.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking glucomannan if you are pregnant or breast-feeding. Stay on the safe side and avoid use.

Diabetes: Glucomannan may interfere with blood sugar control. Monitor blood sugar closely if you have diabetes and use glucomannan.

Surgery: Glucomannan might interfere with blood sugar control during and after surgery. Stop using glucomannan at least 2 weeks before a scheduled surgery.



Moderate Interaction

Be cautious with this combination

  • Medications for diabetes (Antidiabetes drugs) interacts with GLUCOMANNAN

    Glucomannan can decrease blood sugar in people with type 2 diabetes. Diabetes medications are also used to lower blood sugar. Taking glucomannan along with diabetes medications might cause your blood sugar to go too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.<br/><br/> Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.

  • Medications taken by mouth (Oral drugs) interacts with GLUCOMANNAN

    Glucomannan absorbs substances in the stomach and intestines. Taking glucomannan along with medications taken by mouth can decrease how much medicine your body absorbs, and decrease the effectiveness of your medication. To prevent this interaction, take glucomannan at least one hour after medications you take by mouth.



The following doses have been studied in scientific research:



  • For constipation: 2-4.5 grams per day, taken in single or split doses, for up to 12 weeks.
  • For high cholesterol: Various glucomannan doses and dosage forms have been used for up to 12 weeks. These include eating biscuits containing 0.5-0.7 grams of glucomannan per 100 kcal, taking 2.4-3.9 grams of glucomannan supplements daily, eating bars containing 3.33 grams of glucomannan three times daily, or eating foods containing 5-10 grams of glucomannan daily.
  • For diabetes: 3-4 grams per day for up to 8 weeks. Eating biscuits containing 0.5-0.7 grams of glucomannan per 100 kcal has also been used for 3 weeks. A specific supplement providing 2.5-7.5 grams of glucomannan has also been used with meals.

  • For constipation: 100 mg/kg taken once or twice daily (up to a maximum of 5 grams daily) for up to 12 weeks.
  • For high cholesterol: 1 gram twice per day for 8 weeks in children aged 6 years and under. 2-3 grams in single or split doses daily for 8 weeks in children aged 6 years and older.

View References


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