Rheum palmatum

Chinese rhubarb
The blooming white flowers of a Chinese rhubarb
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Core eudicots
Order:	Caryophyllales
Family:	Polygonaceae
Genus:	Rheum
Species:	R. palmatum
Binomial name
Rheum palmatum L.

Rheum palmatum, commonly called Turkey rhubarb, Chinese rhubarb, Indian rhubarb, Russian rhubarb or rhubarb root (and within Chinese herbal medicine da-huang),^[1] is a highly regarded medicinal plant, known for its health benefits.

Description

Loosely branched clusters of matured red flowers found on the lobed-leafed Chinese rhubarb.

The species ““R. tanguticum”” and ““R. officinale,”” also under the categorical term of the Chinese drug ““da-huang,”” are closely related to ““Rheum palmatum””.^[2] Today, these three species are regarded as superior in performance to other species-existing rhubarbs.^[2] Though “”Rheum palmatum”” is commonly misinterpreted to be one in the same with the familiar “”R. rhubarbarum”” garden rhubarb we eat, there are several facets falsifying this assumption.^[1] Size is the most evident of the facets used to differentiate these two closely related species.^[1] While most garden species only grow to a mere few feet in height, Chinese rhubarb can produce as high as a “six to ten foot jointed stalk,” with loosely branched clusters of flowers along the tips that mature red in color from their oftentimes yellow or white blooms.^[1] Its leaves are rather “large, jagged and hand – shaped,” growing in width of at least two to three feet.^[1]

It is important to recognize that only those species of “”rheum”” with lobed leaves are accredited for their medicinal use.^[1] Subsequently, garden rhubarb, “”R. rhubarbarum,”” as well as any other variety of species with either “wavy” or “undulating leaves” are not founded for any medicinal purpose.^[1] Additionally, one can decipher Chinese rhubarb by its rather thick, deep roots whereas the perennial garden plant is composed predominantly of “fleshy rhizomes and buds (http://www.rhubarbinfo.com/growing).

Habitat, cultivation and preparation

Though native in the regions of western China, northern Tibet, and the Mongolian Plateau, Chinese Rhubarb was used immensely in other parts of the world, such as Europe, for hundreds of years before its source of plant identity was actually discovered in the 18th century.^[1] As a consequence of these findings, today Chinese rhubarb is also found flourishing in the West and in the wild.^[2] It is extensively cultivated, no doubt for its great medicinal advantages and uses.^[2] Like all flowering plants, it is grown from the protective coat of a seed in the spring, or by “root division” in the seasons of Spring or Autumn, where the temperature is not yet too hot or too cold.^[2] A rather spacious environment where it can receive an abundance of sunlight for the production of sugars, as well as its development in “well-drained soil,” proves to be most efficient for the augmentation of this species.^[2] Since it is the roots and rhizome which serve as this plant’ source of medicinal usage, special care is taken in their preparation.^[1] When 6–10 years old, the rhizomes of these plants are removed from the ground in the Autumn when both its stems and leaves changed to yellow wild.^[2] Furthermore, the removal of the lateral rootlets and the crown are removed, leaving only the root.^[2] Any debris around the root is cleaned off, the coarse exterior bark removed, and the root cut and divided into cube-like pieces to increase its surface area, thereby decreasing the time needed for drying.^[1]

Traditional and current medicinal uses

The cut-up and dry root of Chinese rhubarb

Out of the numerous herbs founded for their medicinal benefits toward health ailments in early civilizations, Chinese rhubarb remains one of the mere few which is still used today both “conventional and herbal medicine."^[2] The very first accounts are found in ancient Chinese writings, dating all the way back to 2700 B.C...^[3] By studying Chinese history over time, it becomes evident that it was renowned, even then, for its purging effects, as well as its ability to suppress feverish conditions (Foster): it was taken by an emperor in the Liang dynasty (557-579) for fever, used as gift-bearing means to an emperor of the Tang dynasty (618-907), used to combat the plague in the years which the Song dynasty ruled (960-1127), and used as a suicidal measure by a general of the Ming dynasty (1368–1644).^[1] With its several medicinal uses, it wasn’t long before this potent plant began making its way to other parts of the world. In fact, it became one of the most prominent items traded along the Silk Road.^[1] A rhubarb monopoly initiated in Imperial Russia in 1731, stiffly regulating its trade from “China via the Asian steppes to Moscow and St. Petersburg, where its root was shipped to the rest of Europe.".^[1] For 125 years thereafter, rhubarb-root imports were governed solely by what was known as the “Rhubarb Office.” ^[1] This, “office” of course ceased once China opened its ports to the Western nations, allowing for free trade.^[1] Some of the common names associated with Rheum palmatum: “Russian rhubarb”, “Turkey rhubarb,” and “Indian rhubarb,” are directly affiliated with the trade routes for rhubarb from China.^[1]

In ancient China, rhubarb root was taken and recognized as a means to cure stomach ailments and as a “cathartic” (an agent used to relieve severe constipation), as well as its use as a poultice (a preparation of fresh, moistened, or crushed dried herbs, applied externally) for “fevers and edema” (swelling caused by fluid retention in the tissues of the body).^[1] It was given its Latin name by the renowned Carolus Linnaeus in the year 1759, and made to augment its proliferation to British botanical gardens around 1762.^[1]

The conditions treated by Chinese rhubarb in ancient times, are the same it is used to treat today.^[1] The root (the predominantly medicinal part of the species) is still known for its astringent capabilities (as well as a strong laxative); “the tannins in the root caused an astringent action making it useful in the early stages of diarrhea, dysentery, and other intestinal problems." ^[1] It also serves antibacterial use in its ability to treat” toothaches, shingles, fevers, hypertension, burns, acute appendicitis, acute infectious hepatitis, conjunctivitis, swelling and pain of gums, and sores of the mouth or tongue." ^[1]

Today, Rhubarb festivals persist in areas “all over the U.S., Canada, England, and Australia.^[1] These “gatherings” appeal to both travellers and “rhubarb buffs” all around the world.^[1] For instance, the first International Symposium on Rhubarb was held in China in 1990 (Foster). Its objective was to verify the scientific data and treatment of Chinese Rhubarb used by Chinese pharmacopoeias! ^[1]

Medicinal

The Silk Road

• Anthraquinones (about 3-5%), rhein, aloe-emodin, emodin wild ^[2]
• Flavonoids (catechin) wild ^[2]
• Phenolic acids wild ^[2]
• Tannins (5-10%) wild ^[2]
• Calcium oxalate wild ^[2]

Key actions

• Laxative ^[2]
• Anti-inflammatory ^[2]
• Astringent ^[2]
• Stops bleeding ^[2]
• Antibacterial ^[2]

Caution

Though the root of the Chinese rhubarb is a key facet of herbal medicine, its leaves can actually be poisonous if consumed in a high enough dosage.^[1] The oxalic acid crystals found in the leaves may cause a health risk.^[1] Due to the swelling of the tongue and throat, breathing canals become constricted, ultimately preventing breathing.^[1] Patients with “arthritis, kidney problems, inflammatory bowel disease, or intestinal obstruction” should refrain for consumption.^[1]

Additionally, pregnant women should avoid any intake since Rhubarb may cause uterine stimulation.^[1] If taken for an extended amount of time, adverse effects include: “hypertrophy of the liver, thyroid, and stomach, as well as nausea, griping, abdominal pain, vomiting, and diarrhea.” ^[1]

Research highlights

Emodin, an active component of rhubarb root

• Rhubarb extract may have beneficial effects on patients with diabetes. In an animal study conducted on “diabetic rats with nephropathy,” rhubarb extract was found to inhibit the swelling associated with diabetes, at an early stage. Subsequently, the extract may have become significant in the early stages of “human diabetic kideney disease.^[4]
• In a clinical trial testing patients with terminal end-stage kidney failure, a decrease in negative blood markers and an overall increase in positive blood markers was observed in the blood tests examining the effect of rhubarb extract.^[4]
• Taking emodin orally, an active ingredient of rhubarb root, was shown to cure “intravaginal infections in mice.” ^[4]
• In a “10-year controlled clinical double-blind trial at the Xiang Shan TCM Hospital in Shanghai,” it was found that all patients using the three types of alcohol-extracted rhubarb tablets to treat “chronic upper digestive bleeding,” stopped bleeding within a remarkable 56 hours.^[4]
• “Researcher Deng Wenlong, of the Sichuan Provincial Institute of Chinese Materia Medica,” advocated immensely for the beneficial use rhubarb has in medicine. He presented his case at “Chengdu University of TCM in China,” focusing on rhubarb’s ability to treat both fevers and inflammatory diseases effectively. He led a discussion describing how endotoxins (“chemicals that are released into the host as a result of the breakdown of the cell walls of gram-negative bacteria”) can be controlled and suppressed with the human body. It is evident from many findings that endotoxin levels increase significantly in the blood when in stressful environments and situations, inflammation, or infection. The bowel, as it would have it, is heavily affected by this increase in blood endotoxin. With the use of rhubarb, however, Wenlong was able to convey how endotoxin was effectively removed from the bowel, resulting in a faster recovery time from “animals affected with a variety of febrile diseases.” ^[4]
• In lab tests conducted with mice, Emodin has also been proved to inhibit leukemia cells and other cancerous cells.^[4]
• In humans, rhubarb has significant influence on the prevention and delay of renal failure, and the reduction of symptoms such as nausea and anorexia nervosa.^[4]

References

1. ^ ^{a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad} Foster, Steven. Desk Reference to Nature's Medicine. Washington, D.C.: National Geographic Society. pp. 104–105. ISBN 0-7922-3666-1. 
2. ^ ^{a b c d e f g h i j k l m n o p q r s} Chevallier, Andrew (2000). Natural Health: Encyclopedia of Herbal Medicine. New York, New York 10016: Dorling Kindersley. pp. 127. ISBN 0-7894-6783-6. 
3. ^ Chmelik, Stefan (1999). Chinese Herbal Secrets. Garden City Park, New York 11040: The Ivy Press Limited. pp. 20–29. ISBN 0-89529-986-0. 
4. ^ ^{a b c d e f g} Tillotson, Alan (2001). The One Earth Herbal Sourcebook. New York, NY 10022: Kensington Publishing Corp.. pp. 190–192. ISBN 1-57566-617-0.