It must have been difficult for a plant called devil's tongue and voodoo lily to make it onto the dinner plate. Yet thankfully it did in China, under the name moyu or magic taro.

For about 2,000 years, the plant officially known as konjac has been cultivated in China for its nutritious tuber.

The plant's popular names no doubt derive from its distinctive appearance. Reaching heights upwards of five feet, it produces a giant flower that consists of a stiff, fiery-red spike jutting out of a purplish-red spathe. The spathe - the wrap-around petal distinctive of lilies - is often more than a foot high. The spike is what looks like a devil's tongue - it shoots up out of the spathe, rising as much as two or three times taller, and twists slightly.

As a member of the amorphophallus genus, konjac grows in only certain regions of Asia and Africa. In China, the plant is grown in the Yangtze River valley, the southwest and northwest parts of the country.

Konjac flour derived from the tubers has a long history of use in both China and Japan for making noodles or gelatin to add to stews, sauces and soups. The tuber renders these foods richer, thicker, and more satisfying in much the same way that white flour or corn starch improves the texture of similar foods in the West.

In addition, Chinese people have used konjac as a folk remedy since ancient times.

In "Shennong Bencaojing," a classic text on herbal medicine by Tao Hongjing of the Han Dynasty (206 BC-220 AD), konjac was first listed as a medicinal herb for skin care, digestive diseases and coughs.

The wide use of the plant was also recorded in the medical works of the dynasties that followed, including "Bencao Gangmu (Great Compendium of Herbs)" by the master Chinese herbalist Li Shizhen (1518-93).

Modern research by the pharmaceutical and food industries has identified konjac as a valuable medicinal ingredient as well as a versatile hydrocolloid with broad applications in their sector.

Dietary fibre

Konjac contains beta carotene, thiamine, and a number of minerals which are good for health. But the most impressive ingredient in konjac is glucomannan. Glucomannan is a polysaccharide (long chains of simple sugars, primarily mannose and glucose) which is classified as a soluble dietary fibre.

"One of the most important components of a healthy diet is fibre," said Zhang Maoyu, a professor with West China University of Medical Sciences in Chengdu, Southwest China's Sichuan Province, who has researched konjac for years. "While it may not be the most exciting part of the diet, eating foods high in fibre is essential for good health and reducing risk of several diseases."

Dietary fibre is food carbohydrate that is not digested or absorbed and which contributes to positive physiological functions in the body.

Most scientists classify dietary fibre as either "soluble" or "insoluble." This refers to whether the fibre dissolves in hot water.

Like many soluble fibres, glucomannan can bind with a variety of substances in the digestive tract to slow digestion, relieve constipation and reduce the absorption of fat and carbohydrates.

Scientific studies continue to produce new evidence to support the need to increase fibre in the diet.

"When we eat soluble fibre, it traps fatty substances in the intestines, thereby helping to prevent their absorption by the body. This is why soluble fibres help to lower blood cholesterol levels," explained Zhang.

Over the past few years, Zhang and his colleagues have studied the medical effect of konjac glucomannan (KG) on diseases such as diabetes and coronary heart disease.

Spread of disease

Despite significant achievements in treatment and preventive measures, the prevalence of diabetes has risen dramatically in the country over the last few decades.

"There is a continued need for new and more effective therapies. An increasing number of people are using dietary and herbal supplements," Zhang said.

Zhang's study indicates that when used along with conventional treatment, KG not only helps normalize and maintain blood sugar levels in patients with diabetes, it also lowers both cholesterol and systolic blood pressure.

"We have generated a mounting body of evidence to support the claim that KG may be useful in improving diabetes control, reducing associated risk factors such as hyperlipidemia and hypertension, and ameliorating insulin resistance," Zhang said.

Statistics show that coronary heart disease has become one of the leading causes of death in China. And scientific studies have reported a direct relationship between blood cholesterol concentrations and coronary heart disease.

Like other soluble fibres, KG appears to lower blood cholesterol and may help to reduce the risk of coronary heart disease.

Experimental studies also indicate that KG may protect against certain types of cancer.

For those who are over the age of 60, this is welcome news.

When elderly people are given glucomannan, the bacteria in the gut changes and encourages the growth of the so-called "good bacteria" such as bifidobacterium which helps maintain good health.

Increases in good bacteria are associated with a reduction in pro-cancerous nitrosamines, proteins thought to be responsible for the development of liver cancer and other cancers. Good bacteria also encourage better gut motility - motion, including peristalsis that leads to a bowel movement - thereby helping to move waste products out of the body before they can promote cancer or other illnesses.

KG is also an effective treatment for many with chronic constipation. Like most food fibres, glucomannan acts as a bulking agent in the colon, which stimulates peristalsis.

In some trial cases, patients given either 3 or 4 grams daily noted an average increase of three and six more bowel movements per week, respectively, without additional diarrhoea or flatulence.

Since glucomannan can absorb up to 200 times its weight in water, it has been used as a dietary supplement to promote weight loss.

When ingested, it takes on a jelly-like consistency and expands to make the stomach feel full. People are therefore sated more quickly and are less likely to overeat, according to results of trials in which obese patients were put on calorie-restricted diets and glucomannan.

Future health food

These studies provide support for food manufacturers who propose replacing white flour with konjac flour, not just to clean the intestines, but to serve as a weight-loss ingredient in many common foods.

Although konjac is not the only plant source of glucomannan (aloe, for example, also contains this fibre), "it is the most accessible source," said Liu Peiying, director of the China Konjac Association.

Other plant sources containing additional ingredients may not be as pure in glucomannan content as konjac tubers are.

As a hydrocolloid and dietary fibre, konjac has unique jelling and viscosifying properties and can work synergistically with most other gums to enhance multi-gum systems. Konjac offers both cold and hot solubility and permits both hot and cold processing.

These properties have made konjac a versatile food and beverage ingredient.

A traditional food in parts of Asia, konjac has now become one of the most important ingredients in the food and beverage industries worldwide. Its combination of health value and functional properties have also made it the most important ingredient for health food and nutritional beverages, said Liu.

Started as a traditional food in parts of Asia, konjac has now become one of the most important ingredients in the food and beverage industries worldwide and the combination of its health value and functional properties have also made it the most important ingredient for health food and nutritional beverages, said Liu.

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