Brand-Miller JC, Atkinson FS, Gahler RJ, et al. Effects of added PGX, a novel functional fibre, on the glycaemic index of starchy foods. Br J Nutr 2012;108(2):245-8. 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. Mixed with water, glucomannan expands and can absorb up to 50 times its weight. Therefore, the recommended dosage of glucomannan is lower compared to other fiber supplements.

However, in a study of 72 children, this fiber was not more effective than the placebo in treating constipation [ 21]. Insufficient Evidence For In a study of 22 diabetic subjects, this fiber helped decrease blood glucose levels and cholesterol [ 12].The Chinese study also found that those taking the Glucomannan supplement had improved levels of healthy gut bacteria including lactobacilli and bifidobacteria, and improved concentrations of short-chain fatty acids 5, suggesting that Glucomannan can also be used as a prebiotic. How much Glucomannan do I need to take to feel the benefits? High cholesterol. Taking glucomannan by mouth seems to improve cholesterol levels in people with or without high cholesterol. Side effects of supplementation may include flatulence, stomach pain , and gut obstruction [ 2, 49]. 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. One study on 31 children found that supplementing glucomannan was beneficial for treating chronic constipation with no significant side effects. Significantly fewer children complained of abdominal pain, too. 12

Another study with pregnant women suggested that supplementing glucomannan could help improve their constipation symptoms. The participants reported that taking glucomannan improved consistency and frequency of stools. 13 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.

7 of the best glucomannan supplements

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. 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.

Henry DA, Mitchell AS, Aylward J, et al. Glucomannan and risk of oesophageal obstruction. Br Med J 1986;292:591-2. National Institutes of Health. Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Total Water and Macronutrients. Glucomannan does not have any effect on weight loss unless it is taken before a meal. ... This can be avoided by taking the medication at least four hours after or one hour before ingesting glucomannan. Summary Glucomannan is generally considered safe. The suggested dosage is 1 gram, taken 3 times per day with water.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. Glucomannan supplements come in various forms, including glucomannan capsules and powders which can be made up into drinks.

Janani F, Changaee F. The effect of glucomannan on pregnancy constipation. J Family Med Prim Care. 2018;7(5):903‐906. doi:10.4103/jfmpc.jfmpc_168_18 In addition, in two studies, each of 20 diabetic adults, glucomannan taken before a meal decreased the spike in blood sugar levels and decreased appetite by decreasing ghrelin [ 13, 3]. National Center for Biotechnology Information, U.S. National Library of Medicine. Using the adequate intake for nutrient assessment of groups.Fazelian S, Rouhani MH, Bank SS, Amani R. Chromium supplementation and polycystic ovary syndrome: A systematic review and meta-analysis. J Trace Elem Med Biol. 2017;42:92-96. doi:10.1016/j.jtemb.2017.04.008 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. Chmielewska A, Horvath A, Dziechciarz P, Szajewska H. Glucomannan is not effective for the treatment of functional constipation in children: a double-blind, placebo-controlled, randomized trial. Clin Nutr 2011;30(4):462-8. 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. 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.