Glucomannan is a soluble, bulk-forming fiber derived form the konjac root (Amorphophallus konjac). Clinical studies have demonstrated that Glucomannan can provide temporary relief of constipation and may help to maintain serum lipid levels already within the healthy range. In addition, because Glucomannan helps to promotes satiety (feeling of fullness), it can be an effective addition to a weight management plan that includes a healthy diet and exercise program.

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http://en.wikipedia.org/wiki/Glucomannan

http://en.wikipedia.org/wiki/Konjac_glucomannane