Coix is a plant whose botanical name is Coix lacryma-jobi. It belongs to the Gramineae (or Poaceae) family. Coix is used in traditional Chinese medicine, where it is called yi yi ren. In English it is also known as Job's tears.
Coix is an annual plant that grows wild to a height of about 3 ft (1 m) in sunny but moist grasslands. It is also cultivated in many parts of the Orient. Coix may have originated in East Asia, but it is now found throughout East India, China, Japan, the Philippines, northern Africa, the Caribbean, Central America, northern South America, and the United States. The plant has narrow, ribbon-like leaves. The seed with the husk removed is used medicinally. In some areas coix is cultivated as a food grain. The seeds contain about 52% starch, 18% protein, and 7% fat, giving them a higher protein-to-carbohydrate ratio than other cereal grains.
Coix is used as both a healing herb and a food. The seeds, with the husks removed, are important in traditional Chinese medicine. These are said to have a cool nature and a sweet, bland taste. In traditional Chinese medicine, coix seed is used to treat internal dampness and damp-heat conditions, especially disorders of the spleen, stomach, lungs, and large intestine.
Chinese herbalists used coix to improve water flow through the body. It is used to promote urination and as a diuretic to treat edema. It can be used to reduce pain and spasms in the legs when there is also swelling of the legs. Coix is also used to treat such conditions of the gastrointestinal system as diarrhea, poor digestion, and abdominal bloating.
Other claims are also made for coix seed. It is said that a tea made from the boiled seeds will help to cure warts, and that in general coix is good for the skin, helping to nourish and soften it so that it looks smooth and healthy.
Coix is often used in formulas that treat arthritis and rheumatism, conditions believed to be caused by excess dampness according to traditional Chinese medicine. Chinese herbalists also use it to treat appendicitis, lung disease, lung abscesses, beriberi, and cancer.
The seeds of coix are said to have anti-inflammatory, antiseptic, and fever-reducing properties. It is claimed that they can prevent spasms, lower blood sugar, and act as a sedative. The coix root has been used to treat menstrual disorders.
There is no doubt that coix also has value as a food grain, although the seedcoat is hard to remove, making it difficult to produce flour. Coix can be cooked like barley or rice, however, and the flour can be used to make bread. Parched coix seeds are used to make tea, and a coffee substitute can be made from the roasted seeds of some Chinese subspecies.
With so many claims made for coix, scientific interest in the plant is quite high. Agricultural scientists are investigating the genetics of coix with an eye toward growing it as a food crop, and medical researchers are looking at its healing properties. In 1994, Chinese researchers isolated a compound from coix that had anti-tumor properties. This compound has not been tested outside the laboratory, however. Many other researchers have investigated the effects of coix on the immune system cells in test tubes and in laboratory animals. Still other researchers have seen test-tube evidence of antiviral activity. It is too early to tell whether these laboratory results will carry over into humans, but given the high interest in coix, more studies are being done that will soon make the findings clearer.
Coix seeds are harvested when the plant ripens in the autumn. The husks are removed and the seed is used either fresh, boiled, roasted, or fermented. In traditional Chinese medicine, a liquor fermented from coix seeds may be given for rheumatism. Coix is also used in combination with other herbs in rheumatism and arthritis formulas
Traditional Chinese herbalists suggest that pregnant women not use coix.
In traditional Chinese medicine, coix has been used without any undesirable side effects. There are indications, however, that people who eat large amounts of coix as food can become dehydrated.
Coix is has been used for thousands of years in conjunction with other herbs with no reported interactions. Since coix is used almost exclusively in Chinese medicine, there are no studies of its interactions with Western pharmaceuticals.
Molony, David. Complete Guide to Chinese Herbal Medicine. New York: Berkley Books, 1998.
Teegaurden, Ron. The Ancient Wisdom of the Chinese Tonic Herbs. New York: Warner Books, 1998.
American Association of Oriental Medicine (AAOM). 433 Front Street. Catasauqua, PA 18032. (610) 266-2433.
Plants for a Future. "Coix lacryma-jobi." http://www.pfaf.org.