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Chinese Rhubarb - Some Benefits on Usage of Chinese Rhubarb
Taxonomic Class
Polygonaceae
Common Trade Names
Dahuang Liujingao, Extractum Rhei Liquidum
Common Forms
Available as tablets and water- and alcohol-based extracts, syrups, and tinctures.
Source
Active components are derived from the dried root bark of Rheum palmatum, a large, perennial herb that is native to the mountains of Tibet and northwest China.
Chemical Components
Chinese rhubarb contains anthraquinones, stilbenes, and tannins. The anthraquinones occur as glycosides and have been identified as aloe emodin, chrysophanol, emodin, and rhein. Other substances include phenolics (such as catechin, gallic acid, and glucogallin) and sennosides A,B,and C.
Actions
The herb's dramatic purgative or laxative effect is attributable to rhein and sennosides. Sennosides act on the large intestine to increase motility after being degraded by microorganisms in the colon. Increased laxative activity appears to correlate with sennoside content. Anthraquinones exhibit laxative and antimicrobial effects.
Rhubarb extract has been studied in chronic renal failure in the rat . One study found rhubarb to decrease the severity of proteinuria, decrease BUN levels, and attenuate the severity of glomerulosclerosis.
Rhein and emodin inhibit mitochondrial energy production. This may explain the inhibitory effect of rhubarb extracts on renal growth. Hypermetabolism is implicated in initiation of remnant kidney scarring.
In patients with upper GI bleeding, rhubarb has been found to increase blood vessel constriction and promote hemostasis; the mechanism of this action is unknown .
Reported Uses
Chinese rhubarb has been used medicinally for centuries as an antidiarheal and a laxative and to treat conjunctivitis, GI bleeding, indigestion, jaundice, menstrual disorders, and traumatic injuries. It has also been used topically to treat burns, scabs, and sores and as an astringent or styptic to stop bleeding.
The combination of an ACE inhibitor, captopril, and Chinese rhubarb was found to be superior to either agent alone in slowing the progression of renal failure . Similar results were obtained with rhubarb and other adjuvant drugs. Chinese researchers concluded that such treatments may be used as transitional measures in chronic renal disease before more radical therapies are instituted .
In patients with GI bleeding, rhubarb was found to help control bleeding, decrease blood loss, reduce the need for clotting agents, resolve fever, increase peristalsis of the colon without affecting the stomach or duodenum, and help eliminate extravasated bleeding.
Rhubarb stalk fiber was studied in hypercholesterolemic men and was shown to lower serum total cholesterol and LDL levels .
Dosage
Traditional uses suggest the following doses:
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For constipation, 'Ic to I tsp P.O. daily of tincture or I to 2 tsp P.O. daily of decoction.
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For diarrhea, I tsp P.O. daily of tincture or decoction.
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For upper GI bleeding, 3-g tablets or powder P.O. b.i.d. to q.i.d.
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Use lower-strength preparations for older children and patients over age 65.
Adverse Reactions
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GU: urine discoloration (bright yellow or red).
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Skin: contact dermatitis (from handling the leaves).
Interactions
None reported.
Contraindications And Precautions
Chinese rhubarb is contraindicated in pregnant or breast-feeding patients, in children under age 2, and in patients with intestinal problems, such as ulcers and colitis. Use of the herb for longer than 2 weeks is contraindicated because it can induce a tolerance in the colon.
Special Considerations
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Most of the literature comes from the Orient, making interpretation of published studies difficult.
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Inform the patient that Chinese rhubarb is not the same as rhubarb found in the United States.
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Advise the laboratory that the patient's urine will be bright yellow or red.
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Urge the patient to take Chinese rhubarb for only a short time to avoid such problems as melanosis coli and laxative dependence. .AURT Leaves contain poisonous oxalic acid. Consumption causes abdominal pain, burning in the mouth and throat, diarrhea, nausea, vomiting, and, possibly, seizures and death with ingestion of large amounts.
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Caution the patient against preparing Chinese rhubarb formulations at home to avoid the risk of oxalic acid poisoning. Urge him to keep this plant out of the reach of children and pets.
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Inform the patient that this herb may color the urine bright yellow or red.
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Advise women to stop taking the herb if pregnancy is planned or suspected or if breast-feeding is planned.
Points of Interest
Chinese rhubarb is officially listed in the Chinese Pharmacopia and was mentioned in the Chinese herbal Pen-King (ca. 2700 B.C.). Rhubarb root is one of the oldest and most common Chinese herbal medicines available. It has also been used in the manufacture of liqueurs and aperitifs.
Rhubarb species grown in Europe and North America and used for food and medicinal purposes are less potent than Chinese rhubarb.
Commentary
Active medicinal components of Chinese rhubarb suggest its theoretic application as an agent for GI dysmotility. With safety and efficacy data lacking, the herb cannot be recommended for this use.
The use of Chinese rhubarb in renal failure and GI bleeding appears intriguing, but data are from the foreign literature and difficult to interpret. Future studies should probably focus on these aspects of Chinese rhubarb for potential therapeutic application.
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