Botanical and Common Names
- Family Dioscoreaceae
- Dioscorea villos (China Root, Colic Root, Devil’s Bones, Rheumatism Root, Yuma)
- Dioscorea opposita syn. D. batatas (Shan Yao, Chinese Yam)
Cautions
- It should not be used during pregnancy.
Description
Native to North and Central America, the wild yam has now become naturalized in tropical, semitropical, and temperate climates around the world. It is a deciduous perennial vine climbing to twenty feet with heart-shaped leaves and tiny green flowers. The tuberous rhizome is a pale brown, cylindrical, and twisted.
History
Shan yao has been used medicinally for at least 2,000 years in China, Japan, and Southeast Asia. It forms part of "The Pill of Eight Ingredients" traditionally prescribed in Chinese medicine to treat hypothyroidism, nephritis, and diabetes. As with many plants, the root is also eaten as a vegetable in Asia.
Diosgenin, was first identified by Japanese scientists in 1936. This paved the way for the synthesis of progesterone and of such corticosteroid hormones such as cortisone. Diosgenin was also the starting point in the creation of the first contraceptive pill, despite the fact that there is no suggestion that the plant was used as a contraceptive in the past.
Key Actions
- antispasmodic
- anti-inflammatory
- antirheumatic
- diuretic
- increases sweating
Key Components
- alkaloids
- phytosterols
- steroidal saponins (mainly dioscin)
- starch
- tannins
Medicinal Parts
Rhizome
The rhizome contains saponins, which are used as a precursor for the manufacture of cortisone, estrogen, and progesteronelike compounds. The body lacks the enzymes to convert diosgenin into estrogen or any other steroid, but the estrogen-like effects can happen in most people. However, although diosgenin has been promoted as a "natural progesterone", it does not have any progesterone-like effects.
The outer bark of the wild yam root is high in saponins, including dioscin or diosgenin, as well as such alkaloids as dioscorin. All have anti-inflammatory and muscle relaxant properties that seem to work on the muscles of the abdomen and pelvis, as well as treating arthritic and rheumatic conditions.
The root also contains compounds that can lower high blood cholesterol which, in turn, reduces the risk of gallstone formation while having a favourable effect on the liver.
Although wild yam contains several active constituents and it has been used medicinally for hundreds of years, there are few clinical studies to back up beliefs in its effectiveness, causing some practitioners to be cautious of it. Until such time that science catches up with historical use, and since it is not harmful like pharmaceuticals, take it and if works, great. If not, no harm done.
Traditional Uses
In Central America, the plant has been used to relieve menstrual, ovarian, and labour pains. The Maya and Aztecs were known to have used wild yam to relieve pain.
Wild yam is typically used for rheumatic conditions, digestive complaints, gallbladder colic, dysmenorrhea, and muscle cramps. It is particularly effective in treating irritable bowel syndrome and diverticulitis.
Many of the Dioscorea species have hormonal action and used both as a food and a medicine. Shan yao is an important tonic for the spleen and stomach, and is prescribed for tiredness, weight loss, and lack of appetite. It counters excessive sweating, frequent urination, and chronic thirst. In Chinese medicine, it is given for chronic coughs and wheezing.
Recently, the plant has been proclaimed as a solution to menopausal symptoms and to treat menstrual problems. Modern herbalists are aware of its hormone-like effects and recommend it in various forms, including creams and deodorants.