Chinese Rhubarb

Rheum palmatum

COMMON NAMES

• Chinese Rhubarb
  Da Huang
  Ta-huang

Originating from northwest China and Tibet, rhubarb has been used in medicine for more than 2,000 years. Its use gradually spread through India, reaching Europe during the Renaissance overland via Asia Minor - hence the common name, Turkey rhubarb. Rhubarb was a favorite remedy with early Persian and Arabian physicians. The rhubarb grown for cooking and eating is usually R. rhabarbarum, an 18th-century cultivar.

As early as 114 B.C., caravans carried the dried rhizomes eastward over the high mountains to Bokhara in central Asia, whence they found their way to Europe by way of the Black Sea. Dioscorides and Pliny wrote of rhubarb in the first century A.D. In later centuries, Arabs conducted a busy trade in rhubarb by way of Persia and other parts of the Mideast. In the 1650's, two major routes had been established for importing the medication from China: one through India, the other through Moscow via the Gobi desert and Siberia. By 1687, the Russians had established a monopoly on the trade, in part because they rejected inferior imports and built a reputation for high quality . The monopoly was not broken until about 1860, when the port of Canton was opened to direct trade between China and Europe.

Meanwhile, 18th-century Europeans had begun cultivating the edible garden rhubarb, R. rhabarbarum, for medicinal purposes. Although its rhizomes served folk medicine as a mild laxative, they do not have the medicinal properties that give Chinese rhubarb its powers. In fact, they contain a poisonous substance-as do the leaves-so they probably did more harm than good.

Chinese rhubarb's medicinal components fall into two categories: anthraglycosides and tannins. The first cause the laxative effects; the second are astringents, which have the opposite effect. Hence, depending on the size of the dose and the way in which it is given, the rhizome is effective in treating both constipation and diarrhea. The rhizome is no longer used medicinally in the United States, but its extracts serve as laxatives.

The stalks of R. palmatum (CHINESE RHUBARB) can grow up to 6 feet high and are topped by large, deeply lobed leaves that resemble the human palm in shape (hence the species name). For the sake of these leaves, as well as the spikes of tiny red flowers, Chinese rhubarb is sometimes grown as an ornamental. It is difficult to start from seed, so the plant is almost always propagated from cuttings or by root division.

PARTS USED

Root, rhizome.

USES

History - Chinese rhubarb was first mentioned in the 1stcentury AD Chinese classic Materia Medica and has been grown in the West since 1732. Rhubarb is one of the relatively few herbs still used today in conventional as well as herbal medicine, and is listed in the British Pharmacopoeia of 1988.
Constipation - Large doses of Chinese rhubarb are combined with carminative herbs and taken as a laxative, helping to clear the colon without causing excessive cramps. This is useful for treating constipation where the muscles of the large bowel are weak.
Diarrhea - Small doses of the root are astringent, relieving irritation of the inner lining of the gut, thus reducing diarrhea.
Other medical uses - Homeopathy. Rhubarb can be applied to burns, boils, and carbuncles. Rhubarb is a tonic and mild appetite stimulant and is a useful mouthwash for canker sores.

HABITAT AND CULTIVATION

Native to China and Tibet, where the best-quality rhubarb is still found, Chinese rhubarb now also grows in the West. Rhubarb is found in the wild and is widely cultivated. Rhubarb is grown from seed in spring or by root division in spring or autumn and requires sunny position and well-drained soil. The rhizomes of 6-10-year-old plants are dug up in the autumn after the stem and leaves have turned yellow.

RESEARCH

Anthraquinones & tannins - Chinese rhubarb's medicinal value is largely due to the irritant, laxative, and purgative properties of the anthraquinones and in large doses the rhizome is strongly laxative. The high levels of tannins contained in rhubarb, however, counterbalance the laxative action, and it has been demonstrated that in small doses the tannins predominate, causing a constipating effect.
Antibacterial - Decoctions of the root have been shown to be effective against Staphylococcus aureus, an infectious bacterium that causes canker sores and folliculitis (an acne-type infection of the beard area).

CONSTITUENTS

Rhubarb contains anthraquinones, tannins, calcium oxalate, resins, minerals.

USUAL DOSAGE

Decoction: put 1/2 - 1 teaspoonful of the root in a cup of water, bring to the boil and simmer gently for 10 minutes. This should be drunk morning and evening.
Tincture: take 1 - 2 ml of the tincture three times a day.

APPLICATIONS

ROOT:

TINCTURE - The action of the root varies considerably depending on dose. Low doses (5-10 drops) are astringent and can be used for diarrhea. A slightly higher dose (1 ml) acts as a good liver stimulant and gentle laxative. Very high doses (up to 2.5 ml) have a strong cooling and purgative effect. Use increasing doses (0.5 - 2 ml) of carminatives such as fennel or mint with higher doses of rhubarb to prevent cramps.

DECOCTION - A weak decoction  (up to 0.5 g root per dose) can be used for diarrhea, while a strong decoction (3 g root per dose) is effective for chronic constipation or cramps with delayed menstruation.

WASH - The root is also antibacterial and astringent, and a strong decoction can be used on boils and pustules.

COLLECTION AND HARVESTING

This root is collected in China and Turkey.

COMBINATIONS

Rhubarb should be combined with carminative herbs to relieve any griping that may occur.

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