Yam I Am

Jan 05, 2009
*Special to asia!
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Not just a flavourful addition to the cooking pot, Chinese yam can cure both men's and women's ills.

On the Japanese island of Rishiri, yams and yam products are regarded as a folk remedy for the treatment of impotence, presumably because of the tuber's high Vitamin E content. The Japanese call it nagaimo and grate the raw tuber as a garnish for udon. Koreans have their own variant of yam.

Several species of the tuber are used in Chinese herb formulas. By far the most common is Dioscorea Opposita, which is sometimes simply called "Chinese yam." The Chinese names for it are wai san and shanyao.

In the modern Chinese Materia Medica, dioscorea is listed with the qi tonic herbs because of its traditional use for alleviating diarrhoea, despite its more common use in kidney-nourishing formulas, where it contributes to stabilising the kidneys and treating too frequent urination. It is also used to stem "essence leakage" or spermatorrhea. Dioscorea nourishes the yin. Women can also benefit from it as it is prescribed for vaginal yeast infections.

The tuber tones and stabilises the lungs and kidneys. Traditional Chinese medicine practitioners prescribe it to patients with chronic cough or wheezing and abundance of phlegm. Patients suffering from a lack of appetite, fatigue, shortness of breath, thirst, and sweating get relief from eating it. It is particularly beneficial for the stomach and spleen.

The tuber contains nutrients stored for plant growth, so it is rich in starch and also offers protein. One of the main proteins, called dioscorin, is being investigated for potential health benefits, including antioxidant activity.

A mucilage (starch-protein complex) from the tuber has value in the treatment of diarrhoea, as this substance has binding and anti-irritant action.

However, the main active components of dioscorea are steroidal compounds, diosgenin and its variants. These make up about 2% of the tubers. The pharmacology of diosgenin and the other steroidal compounds from dioscorea have not been investigated to a great extent (superficial studies were done over 20 years ago); however, the effects may overlap those of many similar compounds found in herbal medicines, especially Chinese herbs.

Diosgenin is used as a raw material for pharmaceutical production of steroidal hormones; however, the hormonal activity of the natural compounds is quite weak. Diosgenin is being investigated as a potential treatment for rheumatoid arthritis, though in amounts much larger than would be obtained from wai san in traditional preparations.

Wai san comes in the form of dried slices and fresh tubers in the wet market. It is neutral and sweet. Cooked with meat and other herbs, it aids digestion, regulates blood sugar levels and controls inflammation of the uterus. The dried variety must be soaked for at least 15 minutes before use to remove the powder.

Serves 2
Combine Korean ginseng roots with dry wai san, yok chook, wolfberries and red dates for this nourishing soup. All these herbs are easily available in a Chinese medical hall.

Half a chicken, cut into chunks
25 gm Korean ginseng roots
25 gm dry wai san
25 gm yok chook
15 gm wolfberries
10 red dates
2 litres water
salt to taste


Wash the herbs in running water and boil them in a claypot. Add in the chicken and simmer over low heat for three hours. Add salt to taste. Serve hot.

Serves 2
1 teasp of corn flour
dash of pepper
1 teasp soya sauce
1 teasp sesame oil
1 cup rice, washed
1 whole fresh wai san root, peeled and sliced thinly
½ cup minced pork
1 litre water
1. The fresh wai san needs to be peeled before you slice it thinly. The starchy root starts becoming slimy and more difficult.
2. Marinate the minced pork with the cornflour, pepper soya sauce and sesame oil for 30 minutes.
3. Place rice, water and wai san into a rice cooker. Let congee cook for 30 minutes.
4. Shape minced pork into little balls and drop into the congee.
5. Add 1 teaspoon of salt to the congee and stir well.
5. Switch off the rice cooker after 1 hour. Cover with lid tightly and let congee sit for another 10 minutes to thicken. Serve hot.

The congee should be of a starchy consistency. The wai san imparts a delicate sweet flavour that’s both comforting and delicious. It tastes fabulous on its own even without soya sauce. Add a handful of wolfberries to add more nutrition to the congee. You can also substitute the minced pork with strips of lean pork if you want to avoid fat.


vivienne khooOnce a lifestyle editor at a website, a newspaper journalist and a food editor, Vivienne Khoo writes about luxury hotels, food and travel whenever she is not sub-editing. The perfume industry and essential oils are her pet topics at the moment.

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