Glucomannan which is also classified as a soluble dietary fiber is derived from konjac flour. Konjac flour itself is derived from the Amorphophallus species, plants which are related to the common philodendron house plant and which grow in only certain parts of the world including some regions in China and Japan. The laxative effect of glucomannan is thought to be due to the swelling of glucomannan with consequent increase in stool bulk.

The mechanism of glucomannan's possible hypocholesterolemic activity is likewise unclear. The polysaccharide may stimulate the conversion of cholesterol to bile acids, as well as the fecal excretion of bile acids. Glucomannan may also decrease the intestinal absorption of cholesterol.