Konjac is a common name of the East and Southeast Asian plant Amorphophallus konjac (syn. A. rivieri), which has an edible corm (bulbo-tuber). It is also known as konjaku, konnyaku potato, devil's tongue, voodoo lily, snake palm, or elephant yam.

It is native to Yunnan in China and cultivated in warm subtropical to tropical East and Southeast Asia, from Japan and China south to Indonesia (USDA hardiness zone 6-11). It is a perennial plant, growing from a large corm up to 25 cm (10 in) in diameter. The single leaf is up to 1.3 m (4 ft.) across, bipinnate, and divided into numerous leaflets. The flowers are produced on a spathe enclosed by a dark purple spadix up to 55 cm (22 in) long.

Health Benefits

The high fiber content of konjac has many health benefits. Soluble fiber helps lower cholesterol and blood glucose levels. A diet high in fiber may also help regulate bowel movements, prevent hemorrhoids, and help prevent diverticular disease. A 2008 study found that glucomannan may help prevent constipation. The study showed that adding glucomannan to a low-fiber diet increased the amounts of probiotic bacteria in feces. It also increased bowel movement function by 30 percent.

A 2008 systematic review found that konjac may help lower total cholesterol, LDL (bad) cholesterol, and triglycerides. Konjac also reduced body weight and fasting blood sugar. Researchers concluded that glucomannan could be an adjuvant therapy for people with diabetes and high cholesterol. A later study found that konjac lowered LDL and recommended its use to reduce the risk of cardiovascular disease.

Konjac can reduce acne and improve the health of skin. It’s thought to reduce allergic response and improve wound healing. Research suggests that consuming a mix of glucomannan and American ginseng can lead to a moderate improvement in the management of type 2 diabetes.

Uses

Konjac glucomannan dietary supplements are available in most health food stores. The precise dosage of konjac a person should take depends on their reason for taking it, as well as their age and overall health status.

The Food and Drug Administration (FDA) do not regulate konjac supplements, so it is vital to purchase them from a reputable retailer. Supplement manufacturers can voluntarily submit their products to an independent laboratory for testing of purity and potency, so check the label for this information.

People sometimes use konjac corm powder as an alternative to seafood in vegan food. Some manufacturers also make facial sponges from konjac for people looking to take advantage of the health benefits it has for the skin. Other konjac products include: fruit jelly, flour and noodles.

Side Effects

When taken by mouth: Glucomannan powder or flour is likely safe for most adults when consumed as food. Glucomannan powder and capsules are possibly safe when used as medicine, short-term.

But solid tablets containing glucomannan are POSSIBLY UNSAFE for adults. These tablets may cause blockages of the throat or intestines. Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking glucomannan if you are pregnant or breast-feeding. Stay on the safe side and avoid use. Glucomannan may interfere with blood sugar control. Monitor blood sugar closely if you have diabetes and use glucomannan.

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