Extracted from the root of a native Asian plant called the konjac, glucomannan is high in soluble fiber (the type of fiber that attracts water and turns to gel during digestion). Glucomannan is also said to benefit diabetes patients by lowering cholesterol levels.
Health Benefits of Glucomannan for Diabetes:
So far, relatively few studies have tested glucomannan's effectiveness against diabetes. However, several small studies suggest that glucomannan may offer certain benefits to people with diabetes.
For instance, a 2003 study published in the Journal of the American College of Nutrition found that four weeks of treatment with glucomannan supplements helped guard against elevated glucose levels and improve cholesterol levels in diabetes patients. The study involved 22 diabetes patients with high cholesterol who were not taking cholesterol medication. Results showed that glucomannan was superior to placebo in reducing LDL ("bad") cholesterol and fasting glucose levels (a measure of blood sugar after not eating or drinking for at least eight hours).
There's also some evidence that including glucomannan in your diet may help improve diabetes control. In a 2000 study from Diabetes Care, for example, 11 diabetes patients ate glucomannan-enriched biscuits or biscuits enriched with wheat bran fiber every day for three weeks. Researchers found that consumption of the glucomannan-enriched biscuits lead to greater improvements in blood sugar control and a greater decrease in cholesterol.
Additionally, taking glucomannan in combination with plant sterols (naturally occurring compounds with cholesterol-lowering effects) may help diabetes patients keep their cholesterol in check, according to a 2006 study published in the European Journal of Clinical Nutrition. For the study, 16 diabetes patients and 18 non-diabetic individuals were assigned to one of four treatments for 21 days: supplements containing plant sterols, supplements containing glucomannan, supplements containing a combination of glucomannan and plant sterols, or a placebo. Results indicated that the combination of glucomannan and plant sterols was most effective at lowering LDL cholesterol.
Is Glucomannan Safe for People with Diabetes?
Although consuming glucomannan powder or flour in foods (such as shirataki noodles) is most likely safe, little is known about the health effects of long-term use of glucomannan supplements. However, there's some concern that taking glucomannan supplements in combination with diabetes medication may reduce your blood sugar to dangerously low levels.
Since solid tablets of glucomannan may cause blockages in the throat or intestines, many medical experts recommend opting for supplements that deliver glucomannan powder in capsule form.
Where to Find Them:
Widely available for purchase online, glucomannan supplements can be found in many natural-foods stores and in stores specializing in dietary supplements.
Should You Use Glucomannan to Treat Diabetes?
If you're considering the use of glucomannan supplements for treatment or prevention of diabetes, it's important to consult your physician prior to starting your supplement regimen. Self-treating diabetes (or any other chronic condition) with glucomannan and avoiding or delaying standard care may have serious health consequences.
Chen HL, Sheu WH, Tai TS, Liaw YP, Chen YC. "Konjac supplement alleviated hypercholesterolemia and hyperglycemia in type 2 diabetic subjects--a randomized double-blind trial." J Am Coll Nutr. 2003 Feb;22(1):36-42.
Vuksan V, Jenkins DJ, Spadafora P, Sievenpiper JL, Owen R, Vidgen E, Brighenti F, Josse R, Leiter LA, Bruce-Thompson C. "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 Jun;22(6):913-9.
Vuksan V, Sievenpiper JL, Owen R, Swilley JA, Spadafora P, Jenkins DJ, Vidgen E, Brighenti F, Josse RG, Leiter LA, Xu Z, Novokmet R. "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 Jan;23(1):9-14.
Yoshida M, Vanstone CA, Parsons WD, Zawistowski J, Jones PJ. "Effect of plant sterols and glucomannan on lipids in individuals with and without type II diabetes." Eur J Clin Nutr. 2006 Apr;60(4):529-37.