Konjac is a plant native to warm, tropical parts of Asia. It's popular in East Asian cuisine and known for its high fiber content. Gel derived from Konjac is often used in Western foods as a vegan substitute for gelatin. Konjac has various dietary uses and purported health benefits.
Konjac (Amorphophallus konjac) is a perennial plant that grows from an elongated central corm of up to 24 cm in diameter. The tuber forms at the top of the plant, warped in a large purple leaf. It has many names and is called referred to as konjac mannan, devil's tongue (a Japanese pun on its name), konjac, elephant-foot yam (although it bears no relation to the yam), or snake plant.
Konjac is a fat-, sugar-, gluten-, starch-, and protein-free food. It's primarily composed of glucomannan, a water-soluble fiber that passes through the body undigested. It has significant amounts of potassium, calcium, magnesium, phosphorus, iron, and zinc.
Konjac primarily appears in Asian foods. In Japan its tuber is often used to make shirataki noodles which can be found in most Asian food markets. As a gel or flour, it's often used to thicken foods. It has many uses in confections, as well as special-needs diets.
While its health benefits have not undergone much scientific scrutiny, konjac logically has similar health benefits to other high fiber foods. Konjac is a great food for vegetarian, vegan, diabetic, low-carb, gluten-free, and weight-loss diets. It has been shown to normalize cholesterol levels, prevent high blood pressure, and normalize blood sugar levels. A 2008 study published in SCI's Journal of the Science of Food and Agriculture shows that konjac gum may help protect against strains of Salmonella and E.Coli. Its use as a diet drug have not been widely studied, although it may aid in obesity treatments.
There is some concern over choking related to konjac products, particularly in the E.U., U.S., and Australia. This concern has led to suspensions and bans in some areas of its use in confectioneries and diet pills. It is best to consume plenty of water when consuming konjac or konjac products. As a diet drug, it's not an alternative to exercise and healthy eating habits, and should be used in a role supplemental to these.