Glucomannan

Scientific Name(S): Amorphophallus konjac Koch. Family: Araceae

Common Name(S): Konjac, Konjac mannan, glucomannan

Glucomannan is a water-soluble dietary fiber that's derived from the Konjac root (Amorphophallus konjac). Because glucomannan is found in negligible amounts in food, supplementation is necessary.

Source: Konjac mannan is a polysaccharide derived from the tubers of konjac. It is purified from konjac flour by repeated treatment with cupric hydroxide and subsequent washings with ethanol or by dialysis against water (US patents 3, 973,008 [Aug 3, 1976] and 3, 856, 945 [Dec 24, 1974]).

Uses of Glucomannan

Glucomannan is a dietary fiber that helps to increase stool bulk by absorbing water. This helps stool pass more easily through the colon, preventing unnecessary stress to the colon.

Glucomannan reportedly alleviates constipation, reduces intestinal flora, lowers blood sugar and cholesterol and may possibly promote weight loss and inhibit cancer.

Side Effects of Glucomannan

Severe esophageal and GI obstruction have been reported due to glucomannan tablets. The hypoglycemic effects are potentially dangerous to diabetics.

Dosage

The amount of glucomannan shown to be effective as a laxative is 3-4 grams per day. Effective amounts for lowering blood cholesterol have been 4-13 grams per day. For controlling blood sugar, 500-700 mg of glucomannan per 100 calories in the diet has been used successfully in controlled research. For weight loss, 1 to 3 grams before each meal has been effective. When using glucomannan and other dietary fiber supplements, it is best to start out with a small amount and increase gradually. It is recommended to drink at least 8 ounces of water each time any bulk-forming laxative, including glucomannan, is taken.

Toxicology: Four cases of severe esophageal obstruction due to glucomannan diet tablets have been reported. Seven additional cases were noted during 1984/85 by the Australian Adverse Drug Reactions Advisory Committee. Glucomannan-containing tablets have been banned in Australia since May 1985 because these also carry the potential for inducing lower gastrointestinal obstruction. Encapsulated and powder forms remain available.

Glucomannan use is associated with a reduction in the need for hypoglycemic agents, and the product may result in a loss of glycemic control in diabetic patients. It should be used with great care by diabetic patients.

Summary: Konjac mannan (glucomannan) has been shown to possess many of the pharmacologic characteristics of other polysaccharides. In large doses it has laxative activity and may alter the metabolism of microflora in the intestine. It should be used with care by diabetics, in whom its use may result in altered insulin or hypoglycemic requirements. Konjac mannan may be effective in reducing serum cholesterol levels in man and animals. There is conflicting evidence regarding its use as a weight-reduction aid though it does appear to alter lipid metabolism.