Effective Use of Mild Acting Herbs VI. Coix – Yi Yi Ren
by Subhuti Dharamanada
Coix is the common name for the Chinese medicinal material Coix lacryma-jobi seed. The entire coix plant and its seed pod are commonly called Job’s Tears, which is the English equivalent of the Latin species name: the seed pod often has a tear drop appearance. Linnaeus gave the botanical name in 1753, relying upon an existing popular reference for the tear shaped pods to the Book of Job (e.g., Job said: “before God my eyes drop tears”); it has also been called St. Mary’s tears. World-wide, this plant is best known for the pods (pericarps), which have a hole naturally occurring at each end, making them a useful source of beads for stringing. One popular application is making rosaries, as the beads are especially resistant to damage by moisture and have a valued symbolism of tears.
Figure 1. Christian rosary beads.
The seeds (caryopses) of Coix lacryma-jobi are used as a source of food, sometimes called adlay seed; a variety with soft pods is relied upon for this use (var. ma-yuen = var. adlay), while hard shell pods are used for beads. The plant is of the grass family that produces several edible grains such as wheat, corn, and barley, and though more closely related to corn (maize), the coix seed has a size and appearance approximating that of barley, and has been referred to as coix barley. Most commonly, the food material is polished (the hull is removed), and therefore described as “pearl barley” (however, the term pearl barley is equally applied to ordinary barley that has been polished, so this is not a specific designation for coix). Coix barley has a rather strong taste among the grains, and since most grains are used as a relatively bland food ingredient, coix is usually consumed in relatively small quantities (about 30 grams dried seed per serving), mixed with glutinous rice (“sticky rice”). Coix has a good protein yield compared to rice; more than half the seed is starch. This grain is native to Southeast Asia, ranging from India (its likely point of origin), through Malaysia to China, though it has been cultivated elsewhere. Its use as a food in Asia, both for humans and animals, declined after the introduction of other grain crops with higher yields, such as corn and sorghum.
The seed used as a Chinese medicinal ingredient is called yi yi ren (ren = seed; there are two characters pronounced yi, with different tones, and together they designate this specific plant); in common parlance, it is simply called yi ren or yi mi (the yi grain). Coix was first mentioned in the Shennong Bencao Jing (ca 100 A.D.), mainly for use in treating people with stiffness attributed to inability to contract or stretch the sinews and for “bi syndrome” due to wind-damp (Yang 1998). In the Jingui Yaolue (ca 200 A.D.), the combination of coix and aconite was one of the recommended treatments for a syndrome of “thoracic paralysis.” (Hsu and Wang 1983). The use of coix for stiffness in the limbs is preserved to this day in Japanese practice (Kampo) with Yi Yi Ren Tang (Coix Combination), first introduced by Huang Fuzhong in his book Mingyi Zhizhang (1502 A.D.) and brought to Japan during the major transfer of the Chinese herb system that took place in the 16th and 17th centuries (Hsu and Hsu 1980; Dharmananda 2001). In a recent publication about simple remedies (Xu 1989), a treatment for lumbar pain due to myofibrositis was described: 60 grams coix plus 30 grams white atractylodes (baizhu), decocted and taken as a one day dose.
In recent decades, the original indications for use of coix in China were less frequently mentioned, and, instead, coix became better known as an herb for promoting diuresis in cases where moisture retention occurred secondary to impairment of the internal (yin) organs that circulate and eliminate moisture (spleen, lungs, kidney), with the main effect of the herb being on the spleen. Though yiyiren is one of the weakest of the herbal diuretics (Yang 2002), it is utilized with other herbs to control fluid problems, as in the traditional formula Shen Ling Bai Zhu San (Ginseng and Atractylodes Formula) where coix is combined with several spleen tonics and moisture resolving herbs to treat chronic weak digestion with loose stool. In the book Chinese Medicated Diet (Zhang, et.al. 1988), a recipe for treating ascites secondary to liver cirrhosis is:
Red kidney beans: 30 grams
Coix: 30 grams
Polished round-grained rice: 30 grams
Tangerine peel (chenpi): 3 grams
This is to be boiled to make a gruel that is taken in two meals during the day. The same book also has a recommendation for making gruel of coix with bush-cherry seed (yu li ren) for treating benign prostatic hypertrophy, a disorder which often causes urinary retention. And, for alleviating a wasting disease with loss of appetite, cough, fever, and sweating (as occurs, for example, with tuberculosis), its recommendation is:
Dioscorea (shanyao): 60 grams
Coix: 60 grams
Persimmon frost (shibingshuang): 24 grams
The dioscorea and coix are first cooked until completely softened, and then the persimmon frost (which is the white material appearing on the surface of dried persimmons, being 95% sugar and containing some other ingredients from the persimmon fruit, considered good for nourishing the lungs) is dissolved in the gruel. This food is consumed in two portions for one day.
Coix is attributed a cooling property. Hence, Jiao Shude (Jiao 2003) notes that for treating stiff sinews, one would select chaenomeles (mugua) when the problem is associated with damp-cold, but would select coix when then problem is associated with damp-heat. The cooling property is a mild one which is eliminated by frying, a process used to make the herb better suited for spleen-cold syndromes.
Coix also gained a reputation for beautifying the skin, so women in Southeast Asia have been encouraged to eat coix as a cereal grain, making it a regular practice when possible. A highly concentrated extract of coix produced in Japan (where it is known as hatomugi), is promoted as a support for beautiful skin, hair, and nails. In addition, coix has been included in medicinal formulas for treating skin diseases, such as acne and other swellings, and this application is generalized to treatment of abscesses of the lungs and intestines. Anti-allergy properties have been suggested for coix, so that this seed is sometimes used in treatment of allergic dermatitis (Hsu et.al. 2003).
The dosage of coix to be used is explained well by Jiao Shude: “The dosage is generally 10-20 grams. However, this medicinal is bland in flavor and moderate in strength, so if the disease is severe, it is often necessary to use a larger dose, such as 30-60 grams, and to take it over a long period of time.”
A search for active constituents led to the oil fraction, which makes up about 5-7% of the dried seed. Two components isolated early on were coixenolide and coixol; recently, coix extracts have been standardized to their coixenolide content (see figure 2). Coixol is an agent that appears responsible for antispasmodic type actions, perhaps explaining the traditional use in treating stiff conditions; coixenolide, which makes up no more than 0.25% of the seed, has been investigated for antineoplastic activity (Chang and But 1987). The spleen tonification and mild diuretic aspects of coix may be general properties of grains, rather than specific to coix and its active components, as these are reported as indications for several other grains used in Chinese diet therapy and medicinal formulas.
Figure 2. The chemical structure of coixenolide.
The antineoplastic action of coix and coixenolide has drawn considerable attention. Several decades ago, the Japanese physician Yoshimi Okusa designed a formulation for treatment of stomach cancer that was marketed for some time in Japan, known as WTTC (from the initials of the four ingredients: wisteria, trapa, terminalia, and coix). The inclusion of coix may have been from the suspicion that people who consumed coix as a food grain had lower incidence of stomach cancer, a cancer type that has been especially prevalent in Japan (blamed, in part, on the high consumption of pickled vegetables). Use of WTTC in treating “digestive tract” cancers was reported in China as early as 1962 in the Jiangsu Journal of Traditional Chinese Medicine, with mention of work done in Japan during the 1950s, where one of the main proponents of WTTC was Nakayama Koumei of Chiba University. WTTC has mostly fallen into disuse as the modern cancer therapies have developed; it was tried as a potential aid for enhancing survival among stomach cancer patients following surgery, and it has been modified and used in treating some skin ailments. In a book about treating cancer with Chinese herbs (Hsu 1990), it was suggested that clinical data supported use of WTTC to help prevent recurrence of cancer, but the author gave this cautionary note based on a 1978 report from Japan: “WTTC is not a cure-all drug. Surgery, radiotherapy, and other anti-cancer preparations are usually employed in conjunction with it.”
As indicated in the book Anti-Cancer Medicinal Herbs (Chang 1986), a recommendation for cancer patients (such as those with cancer of the stomach or larynx) was to take 30-60 grams coix, made with glutinous rice as a gruel, every day (year round; the patients also received other treatments). Another recommendation was to combine 500 grams coix with 150 grams tien-chi ginseng (sanqi) and grind it to powder and take 15 grams each time, three times daily (so this would be a daily dose of about 34 grams coix and 11 grams tien-chi); this combination was given for the treatment of uterine fibroids (the ingredient tien-chi is used to stop the symptom of bleeding as well as to vitalize blood circulation).
An extract of the oil of coix has been developed as an injection for potential treatment of cancer under the name Kanglaite, but the research is only in an early stage. Clinical studies were conducted in China during the 1990s, when it was used in liver and lung cancer cases; primarily, it has been used along with standard anticancer protocols in an attempt to improve outcomes (Qian and Liu 2005).
Other substances, such as polysaccharides, called coixans, have also been isolated from the seeds and are being investigated for potential medicinal use. These and the other active components usually have to be isolated by technical means to get a large enough dose for getting medicinal effects. For example, coixenolide is now being obtained by ultrasound-assisted supercritical fluid extraction. These isolates are far removed from the food use and traditional medical use of coix, though they have their basis in pursuing the potential revealed by traditional medicine.
Potentially, a daily consumption of 30 grams of coix seed (e.g., made as a food) over an extended period of time could provide certain benefits that have been implied by laboratory animal studies or claimed in the traditional literature, while special extracts might be used to get an adequate dose of specific active components.
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