Chinese yam mainly refers to the roots of Dioscorea opposita. Thunb., which is a vine plant in the family Dioscoreaceae. Besides, the root of Dioscorea japonica Thunb., a species of wildlife around China, is also used as Shan Yao medicinally because of the similar efficacy. Hence, other names of it include Rhizoma Dioscoreae, nagaimo, Common Yam Rhizome, Dioscorea oppoistifolia, Korean yam, Dioscorea batata, Chinese yam rhizome, Chinese mountain yam, dioscorea yam, Dioscorea villosa, dioscoreae rhizoma, and so on. In China it is basically produced in Henan, Hunan, and regions south of the Yangtze River. Traditionally the one from Henan (Huaiqing) is believed with highest medicinal properties and nutritional value. That’s the reason why it is often called "Huai Shan Yao". It is usually harvested after Frost’s Descent (18th solar term). And there are two types of finished products available – "Mao Shan Yao" and "Guang Shan Yao". The former one still needs to go through steps of scraping off the tertia and drying in the sun or over a fire; based the previous steps the latter one still needs to be soaked until it becomes soft, rubbed and pressed into cylinder, dried in the sun, and finally polished.

TOP 8 CHINA YAM HEALTH BENEFITS 
1) Strengthening the spleen and stomach to aid digestion.
Fresh yam contains amylase, polyphenol oxidase, and other matters, which make it a perfect medicine and food to help digestion and absorption. It helps regardless of it is spleen-yang or stomach-yin deficiency. Therefore, clinically it treats deficient spleen-stomach, loss of appetite, body fatigue, diarrhea and other diseases;

2) Nourishing kidney and enriching essence.
It contains a variety of nutrients, which can make body stronger, nourish kidney, increase sperm count, and improve sperm quality. So, it is widely used for Impotence, Nocturnal Emission, abnormal vaginal discharge, frequent urination, and more;

Chinese Yam

3) Benefiting lung to stop cough.
It contains saponins and mucilage, which have a lubricating and moisturizing effect. Hence, it benefits lung qi, enriches lung yin, and treat chronic cough due to lung deficiency and phlegm;

4) Lowering blood sugar.
Fresh yam contains mucus protein that can lower blood sugar. Therefore, it can be used in the treatment of diabetes or a good diabetic diet;

5) Promoting longevity.
Raw yam contains a lot of mucus protein , vitamins and trace elements, which can effectively stop the precipitation of lipids in the blood vessel wall and thereby prevent cardiovascular. In other words, it tranquilizes the mind, promotes intelligence, and prolongs life;

6) Preventing hepatic coma.
Recent studies have found that it is with sedative effect and can be used to prevent hepatic coma;

7) Soothing mood and regulating sleep.
Unlike ginseng, the medicinal properties of Chinese yams are quite mild and slow. And it can soothe mood and adjust sleep while regulating the function of spleen.

8) Tonifying deficiency.
Zhang Zhongjing, one of the best Chinese physicians in TCM history, was very good at using this herb. In his medical book Jin Gui Yao Lue (Essential Prescriptions of the Golden Coffer), it is used to cure qi-blood deficiency, stomach pain, arthralgia, Amenorrhea, Irregular Menstruation and other symptoms.