Konjac is a common name of the Asian plant Amorphophallus konjac, which has an edible corm (bulbo-tuber). It is also known as konjaku, konnyaku potato, or elephant yam.
It is native to Yunnan in China and cultivated from Japan and China south to Indonesia. It is a perennial plant, growing from a large corm up to 25 cm in diameter. The food made from the corm of this plant is widely known in English by its Japanese name, konnyaku (yam cake), popular in Japan and Korea. Noodles made from konnyaku are called shirataki.
Konjac has been known in Japan since the sixth century as a medicinal food.
The dried corm of the konjac plant contains around 40% glucomannan gum. This makes konjac jelly highly viscous and may be responsible for many of its putative health benefits as used in traditional Chinese medicine, detoxification, tumour-suppression, blood stasis alleviation and phlegm liquefaction. The dietary fiber from the corm of konjac is used as a component of weight loss supplements.
Konjac can also be used for facial massage accessories, which are currently popular in Korea and gaining popularity in the West. Most commonly this is through the use of a konjac sponge, which is unique in that it can be used on sensitive skin that may become easily irritated with more common exfoliating tools (such as a loofahs or washcloths).