Glucomanano, Glucomannane, Konjac Mannan.
Overview InformationGlucomannan is a dietary fiber. It is usually made from the root of the konjac plant. Glucommanan powder, capsules, and tablets are used as medicine.
Orally, glucomannan is used for constipation, weight loss, diabetes, high cholesterol, overactive thyroid (hyperthyroidism), high blood pressure, and stomach conditions called dumping syndrome and functional gastrointestinal disorder.
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 inconsistent.
- 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 high cholesterol.
Insufficient Evidence for
- A stomach condition called 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 glucomannan plus methimazole and propranolol reduce thyroid hormone levels in people with too much thyroid hormone in the body.
- 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.
Side Effects & SafetyGlucomannan 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.
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: Glucomannan doses typically range from 2-4.5 grams daily, taken in divided doses.
- For high cholesterol: Various glucomannan doses and dosage forms have been used, short-term (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 type 2 diabetes: Doses of about 3-4 grams of glucomannan have been used daily 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 of glucomannan has been taken once or twice daily (up to a maximum of 5 grams daily) for up to 12 weeks.
- For high cholesterol: Doses of 1 gram of glucomannan have been taken twice daily for 8 weeks in children 6 years of age and under. Dose of 1.5 grams of glucomannan have been taken twice daily for 8 weeks in children older than 6 years of age.
- Azezli, A. D., Bayraktaroglu, T., and Orhan, Y. The use of konjac glucomannan to lower serum thyroid hormones in hyperthyroidism. J Am.Coll.Nutr. 2007;26(6):663-668. View abstract.
- Bernstein, J. A., Crandall, M. S., and Floyd, R. Respiratory sensitization of a food manufacturing worker to konjac glucomannan. J Asthma 2007;44(8):675-680. View abstract.
- Birketvedt, G. S., Shimshi, M., Erling, T., and Florholmen, J. Experiences with three different fiber supplements in weight reduction. Med Sci Monit. 2005;11(1):I5-I8. View abstract.
- Cesa, F., Mariani, S., Fava, A., Rauseo, R., and Zanetti, H. [The use of vegetable fibers in the treatment of pregnancy diabetes and/or excessive wight gain during pregnancy]. Minerva Ginecol. 1990;42(6):271-274. View abstract.
- Chearskul, S., Sangurai, S., Nitiyanant, W., Kriengsinyos, W., Kooptiwut, S., and Harindhanavudhi, T. Glycemic and lipid responses to glucomannan in Thais with type 2 diabetes mellitus. J Med Assoc.Thai. 2007;90(10):2150-2157. View abstract.
- Chen, H. L., Cheng, H. C., Liu, Y. J., Liu, S. Y., and Wu, W. T. Konjac acts as a natural laxative by increasing stool bulk and improving colonic ecology in healthy adults. Nutrition 2006;22(11-12):1112-1119. View abstract.
- Chen, H. L., Cheng, H. C., Wu, W. T., Liu, Y. J., and Liu, S. Y. Supplementation of konjac glucomannan into a low-fiber Chinese diet promoted bowel movement and improved colonic ecology in constipated adults: a placebo-controlled, diet-controlled trial. J Am.Coll.Nutr. 2008;27(1):102-108. View abstract.
- Doi, K., Matsuura, M., Kawara, A., and Baba, S. Treatment of diabetes with glucomannan (konjac mannan). Lancet 5-5-1979;1(8123):987-988. View abstract.
- Fanelli, V., Angelico, F., Stefanutti, C., Calvieri, A., and Fazio, S. [Effects of the integration of a habitual diet with glucomannan fiber in hypercholesterolemia. A clinical study in familial and sporadic hyperlipoproteinemia with lipo-proteic phenotype IIa and IIb]. Clin Ter. 10-15-1986;119(1):17-23. View abstract.
- Gonzalez, Canga A., Fernandez, Martinez N., Sahagun, A. M., Garcia Vieitez, J. J., Diez Liebana, M. J., Calle Pardo, A. P., Castro Robles, L. J., and Sierra, Vega M. [Glucomannan: properties and therapeutic applications]. Nutr.Hosp. 2004;19(1):45-50. View abstract.
- Hopman, W. P., Houben, P. G., Speth, P. A., and Lamers, C. B. Glucomannan prevents postprandial hypoglycaemia in patients with previous gastric surgery. Gut 1988;29(7):930-934. View abstract.
- Huang, C. Y., Zhang, M. Y., Peng, S. S., Hong, J. R., Wang, X., Jiang, H. J., Zhang, F. L., Bai, Y. X., Liang, J. Z., Yu, Y. R., and . Effect of Konjac food on blood glucose level in patients with diabetes. Biomed.Environ.Sci 1990;3(2):123-131. View abstract.
- Kawamura, Y. and Horio, T. [Effects of chewing exercise on the maximum biting force and chewing performance]. Shika.Kiso.Igakkai Zasshi 1989;31(3):281-290. View abstract.
- Keithley, J. and Swanson, B. Glucomannan and obesity: a critical review. Altern.Ther.Health Med 2005;11(6):30-34. View abstract.
- Kneepkens, C. M., Fernandes, J., and Vonk, R. J. Dumping syndrome in children. Diagnosis and effect of glucomannan on glucose tolerance and absorption. Acta Paediatr.Scand. 1988;77(2):279-286. View abstract.
- Kraemer, W. J., Vingren, J. L., Silvestre, R., Spiering, B. A., Hatfield, D. L., Ho, J. Y., Fragala, M. S., Maresh, C. M., and Volek, J. S. Effect of adding exercise to a diet containing glucomannan. Metabolism 2007;56(8):1149-1158. View abstract.
- Loening-Baucke, V., Miele, E., and Staiano, A. Fiber (glucomannan) is beneficial in the treatment of childhood constipation. Pediatrics 2004;113(3 Pt 1):e259-e264. View abstract.
- Marsicano, L. J., Berrizbeitia, M. L., and Mondelo, A. [Use of glucomannan dietary fiber in changes in intestinal habit]. G.E.N. 1995;49(1):7-14. View abstract.
- Martino, F., Martino, E., Morrone, F., Carnevali, E., Forcone, R., and Niglio, T. Effect of dietary supplementation with glucomannan on plasma total cholesterol and low density lipoprotein cholesterol in hypercholesterolemic children. Nutr.Metab Cardiovasc.Dis. 2005;15(3):174-180. View abstract.
- Marzio, L., Del, Bianco R., Donne, M. D., Pieramico, O., and Cuccurullo, F. Mouth-to-cecum transit time in patients affected by chronic constipation: effect of glucomannan. Am.J Gastroenterol. 1989;84(8):888-891. View abstract.
- Matsuura, Y. Degradation of konjac glucomannan by enzymes in human feces and formation of short-chain fatty acids by intestinal anaerobic bacteria. J Nutr.Sci Vitaminol.(Tokyo) 1998;44(3):423-436. View abstract.
- McCarty, M. F. Nutraceutical resources for diabetes prevention--an update. Med Hypotheses 2005;64(1):151-158. View abstract.
- Morgan, L. M., Tredger, J. A., Wright, J., and Marks, V. The effect of soluble- and insoluble-fibre supplementation on post-prandial glucose tolerance, insulin and gastric inhibitory polypeptide secretion in healthy subjects. Br.J Nutr. 1990;64(1):103-110. View abstract.
- Nakajima, N. and Matsuura, Y. Purification and characterization of konjac glucomannan degrading enzyme from anaerobic human intestinal bacterium, Clostridium butyricum-Clostridium beijerinckii group. Biosci.Biotechnol.Biochem. 1997;61(10):1739-1742. View abstract.
- Nakajima, N., Ishihara, K., and Matsuura, Y. Dietary-fiber-degrading enzymes from a human intestinal Clostridium and their application to oligosaccharide production from nonstarchy polysaccharides using immobilized cells. Appl.Microbiol.Biotechnol. 2002;59(2-3):182-189. View abstract.
- Onishi, N., Kawamoto, S., Nishimura, M., Nakano, T., Aki, T., Shigeta, S., Shimizu, H., Hashimoto, K., and Ono, K. The ability of konjac-glucomannan to suppress spontaneously occurring dermatitis in NC/Nga mice depends upon the particle size. Biofactors 2004;21(1-4):163-166. View abstract.
- Onishi, N., Kawamoto, S., Suzuki, H., Hide, M., and Ono, K. Development of autoantibody responses in NC/Nga mice: its prevention by pulverized konjac glucomannan feeding. Arch.Dermatol.Res 2008;300(2):95-99. View abstract.
- Pittler, M. H. and Ernst, E. Dietary supplements for body-weight reduction: a systematic review. Am.J.Clin Nutr. 2004;79(4):529-536. View abstract.
- Rosado, J. L. and Diaz, M. [Physico-chemical properties related to gastrointestinal function of 6 sources of dietary fiber]. Rev.Invest Clin 1995;47(4):283-289. View abstract.
- Ruszova, E., Pavek, S., Hajkova, V., Jandova, S., Velebny, V., Papezikova, I., and Kubala, L. Photoprotective effects of glucomannan isolated from Candida utilis. Carbohydr.Res 2-25-2008;343(3):501-511. View abstract.
- Salas-Salvado, J., Farres, X., Luque, X., Narejos, S., Borrell, M., Basora, J., Anguera, A., Torres, F., Bullo, M., and Balanza, R. Effect of two doses of a mixture of soluble fibres on body weight and metabolic variables in overweight or obese patients: a randomised trial. Br.J Nutr. 2008;99(6):1380-1387. View abstract.
- Scalfi, L., Coltorti, A., D'Arrigo, E., Carandente, V., Mazzacano, C., Di, Palo M., and Contaldo, F. Effect of dietary fibre on postprandial thermogenesis. Int.J Obes. 1987;11 Suppl 1:95-99. View abstract.
- Shichijo, K., Kobayashi, Y., Fueki, R., Shimoyama, K., and Masaya, M. [2 cases of konjac bronchial asthma found outside the "konnyaku" producing district]. Arerugi 1969;18(2):97-100. View abstract.
- Signorelli, P., Croce, P., and Dede, A. [A clinical study of the use of a combination of glucomannan with lactulose in the constipation of pregnancy]. Minerva Ginecol. 1996;48(12):577-582. View abstract.
- Sood, N., Baker, W. L., and Coleman, C. I. Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis. Am.J Clin Nutr. 2008;88(4):1167-1175. View abstract.
- Tapola, N. S., Lyyra, M. L., Kolehmainen, R. M., Sarkkinen, E. S., and Schauss, A. G. Safety aspects and cholesterol-lowering efficacy of chitosan tablets. J Am.Coll.Nutr. 2008;27(1):22-30. View abstract.
- Vanderbeek, P. B., Fasano, C., O'Malley, G., and Hornstein, J. Esophageal obstruction from a hygroscopic pharmacobezoar containing glucomannan. Clin Toxicol.(Phila) 2007;45(1):80-82. View abstract.
- Vasques, C. A., Rossetto, S., Halmenschlager, G., Linden, R., Heckler, E., Fernandez, M. S., and Alonso, J. L. Evaluation of the pharmacotherapeutic efficacy of Garcinia cambogia plus Amorphophallus konjac for the treatment of obesity. Phytother.Res 2008;22(9):1135-1140. View abstract.
- Venter, C. S., Kruger, H. S., Vorster, H. H., Serfontein, W. J., Ubbink, J. B., and De Villiers, L. S. The effects of the dietary fibre component konjac-glucomannan on serum cholesterol levels of hypercholesterolemic subjects. Hum Nut:Food Serv Nutr 1987;41F:55-61.
- Villaverde, A. F., Benlloch, S., Berenguer, M., Miguel, Rayon J., Pina, R., and Berenguer, J. Acute hepatitis of cholestatic type possibly associated with the use of glucomannan (amorphophalus konjac). J Hepatol. 2004;41(6):1061-1062. View abstract.
- Wood, R. J., Fernandez, M. L., Sharman, M. J., Silvestre, R., Greene, C. M., Zern, T. L., Shrestha, S., Judelson, D. A., Gomez, A. L., Kraemer, W. J., and Volek, J. S. Effects of a carbohydrate-restricted diet with and without supplemental soluble fiber on plasma low-density lipoprotein cholesterol and other clinical markers of cardiovascular risk. Metabolism 2007;56(1):58-67. View abstract.
- Yoshida, M., Vanstone, C. A., Parsons, W. D., Zawistowski, J., and Jones, P. J. Effect of plant sterols and glucomannan on lipids in individuals with and without type II diabetes. Eur.J Clin Nutr. 2006;60(4):529-537. View abstract.
- Zhang, M. Y., Huang, C. Y., Wang, X., Hong, J. R., and Peng, S. S. The effect of foods containing refined Konjac meal on human lipid metabolism. Biomed.Environ.Sci 1990;3(1):99-105. View abstract.
- Arvill A, Bodin L. Effect of short-term ingestion of konjac glucomannan on serum cholesterol in healthy men. Am J Clin Nutr 1995;61:585-9. View abstract.
- Cairella M, Marchini GAD. [Evaluation of the action of glucomannan on metabolic parameters and on the sensation of satiation in overweight and obese patients]. [Article in Italian] Clin Ter 1995;146:269-74. View abstract.
- Chen HL, Sheu WH, Tai TS, et al. Konjac supplement alleviated hypercholesterolemia and hyperglycemia in type 2 diabetic subjects--a randomized double-blind trial. J Am Coll Nutr 2003;22:36-42. View abstract.
- Doi K, Matsuura M, Kawara A, Baba S. Treatment of diabetes with glucomannan (konjac mannan). Lancet 1979;1:987-8.
- Doi K, Matsuura M, Kawara A, et al. Influence of dietary fiber (konjac mannan) on absorption of vitamin B12 and vitamin E (abstract). Tohoku J Exp Med 1983;141:677-81. View abstract.
- Gallaher DD, Gallaher CM, Mahrt GJ, et al. A glucomannan and chitosan fiber supplement decreases plasma cholesterol and increases cholesterol excretion in overweight normocholesterolemic humans. J Am Coll Nutr 2002;21:428-33. View abstract.
- Henry DA, Mitchell AS, Aylward J, et al. Glucomannan and risk of oesophageal obstruction. Br Med J 1986;292:591-2.
- Livieri C, Novazi F, Lorini R. [The use of highly purified glucomannan-based fibers in childhood obesity]. Pediatr Med Chir 1992;14:195-8. View abstract.
- Passaretti S, Franzoni M, Comin U, et al. Action of glucomannans on complaints in patients affected with chronic constipation: a multicentric clinical evaluation. Ital J Gastroenterol 1991;23:421-5. View abstract.
- Shima K, Tanaka A, Ikegami H, et al. Effect of dietary fiber, glucomannan, on absorption of sulfonylurea in man. Horm Metab Res 1983;15:1-3. View abstract.
- Staiano A, Simeone D, Del Giudice E, et al. Effect of the dietary fiber glucomannan on chronic constipation in neurologically impaired children. J Pediatr 2000;136:41-5. View abstract.
- Vido L, Facchin P, Antonello I, et al. Childhood obesity treatment: double blinded trial on dietary fibres (glucomannan) versus placebo. Padiatr Padol 1993;28:133-6. View abstract.
- Vita PM, Restelli A, Caspani P, et al. [Chronic use of glucomannan in the dietary treatment of severe obesity]. Minerva Med 1992;83:135-9. View abstract.
- Vuksan V, Jenkins DJ, Spadafora P, et al. Konjac-mannan (glucomannan) improves glycemia and other associated risk factors for coronary heart disease in type 2 diabetes. A randomized controlled metabolic trial. Diabetes Care 1999;22:913-9. View abstract.
- Vuksan V, Sievenpiper JL, Owen R, et al. Beneficial effects of viscous dietary fiber from Konjac-mannan in subjects with the insulin resistance syndrome: results of a controlled metabolic trial. Diabetes Care 2000;23:9-14. View abstract.
- Walsh DE, Yaghoubian V, Behforooz A. Effect of glucomannan on obese patients: a clinical study. Int J Obes 1984;8:289-93. View abstract.