Frangula purshiana (cascara, cascara buckthorn, cascara sagrada, bearberry, and in the Chinook Jargon, chittem stick and chitticum stick; syn. Rhamnus purshiana, Rhamnus purshianus) is a species of plant in the family Rhamnaceae. It is native to western North America from southern British Columbia south to central California, and eastward to northwestern Montana.
The outer bark is brownish to silver-grey with light splotching (often, in part, from lichens) and the inner surface of the bark is smooth and yellowish (turning dark brown with age and/or exposure to sunlight). Cascara bark has an intensely bitter flavor that will remain in the mouth for hours, overpowering the taste buds.
The leaves are simple, deciduous, alternate, clustered near the ends of twigs. They are oval, 5–15 cm (2″–6″) long and 2–5 cm (¾″–2″) broad with a 0.6–2 cm (¼″–¾″) petiole, shiny and green on top, and a dull, paler green below; and have tiny teeth on the margins, and parallel veins.
The flowers are tiny, 4–5 mm (⅛″–¼″) diameter, with five greenish yellow petals, forming a cup shape. The flowers bloom in umbel-shaped clusters, on the ends of distinctive peduncles that are attached to the leaf axils. The flowering season is brief, from early to mid- spring, disappearing by early summer. The fruit is a drupe 6–10 mm (¼″-½″) diameter, bright red at first, quickly maturing deep purple or black, and containing a yellow pulp, and two or three hard, smooth, olive-green or black seeds.
Range and habitat
Cascara is native from northern California to British Columbia and east to the Rocky Mountains in Montana. It is often found along streamsides in the mixed deciduous-coniferous forests of valleys, and in moist montane forests. Cascara is common in the understory of bigleaf maple forest, alongside red osier dogwood and red alder.
In many areas, the high market demand for cascara bark has led to over-harvesting from wild trees, which may have heavily reduced cascara populations.
Traditional medicine as a laxative
Cascara has been used in traditional medicine as a laxative, although there is insufficient high-quality clinical evidence for such an effect. Cascara remains available in the United States as a dietary supplement.
The dried, aged bark of R. purshiana has been used continually for many years by both Pacific northwest native peoples and immigrant Euro-Americans as a laxative natural medicine, as one of several anthraquinone-containing herbal medicines including the leaf and fruits of senna, the latex of Aloe vera, and the root of the rhubarb plant. Commercially it is called "cascara sagrada" ('sacred bark' in Spanish), while traditionally it is known as "chittem bark" or "chitticum bark".
Spanish conquerors exploring the Pacific Northwest in the 1600s came across many Native peoples using the bark of R. purshiana as a laxative. They gave it the name "sacred bark" (cáscara sagrada) in honor of its effectiveness. By 1877 the U.S. pharmaceutical company Parke-Davis was producing cascara preparations, and soon afterwards cascara products were being exported overseas to European markets. The explosion of the cascara industry caused great damage to native cascara populations during the 1900s, as a result of overharvesting.
In 1999, cascara made up more than 20% of the national laxative market in the U.S., with an estimated value of $400 million. Cascara was found in more drug preparations than any other natural product in North America, and is believed to be the most widely used cathartic in the world.
Numerous quinoid phytochemicals are found in the bark of cascara. The chemicals possibly responsible for the laxative effect are the hydroxyanthracene glycosides, which include cascarosides A, B, C, and D. Cascara contains approximately 8% anthranoids by mass, of which about two-thirds are cascarosides. The hydroxyanthracene glycosides may trigger peristalsis by inhibiting the absorption of water and electrolytes in the large intestine, which increases the volume of the bowel contents, leading to increased pressure.
The hydroxyanthracene glycosides are not readily absorbed in the small intestine, but are hydrolyzed by intestinal flora to a form that is partly absorbed in the colon. Hydrolysis of the cascarosides results in the formation of aloins, such as barbaloin and chrysaloin. Some of the chemical constituents present in the bark may be excreted by the kidneys.
The bark is collected in the spring or early summer, when it easily peels from the tree. Once stripped from the tree, the bark must be aged for at least 1 year before use, because fresh cut, dried bark causes vomiting and violent diarrhea. This drying is generally done in the shade to preserve its characteristic yellow color. This process can be quickened by simply baking the bark at a low temperature for several hours. In her book, Major Medicinal Plants, Dr. Julia Morton suggested using a dosage of 10–30 grains, dissolved in water, or 0.6–2 cc for fluid extract. James A. Duke suggested an effective dosage of approximately 1 to 3 grams (15 to 46 gr) dried bark, or 1 to 2.5 grams (15 to 39 gr) powdered bark.
Laxative should only be used on a short-term basis (no longer than 7 days), and should not be used by pregnant women (because cathartics such as cascara can induce labor), by lactating women (because the active compounds can be transferred to the infant), or by people with intestinal obstructions or injuries. Laxatives should also not be used by people with Crohn's disease, irritable bowel syndrome, colitis, hemorrhoids, appendicitis, or kidney problems.
FDA regulation and adverse effects
Cascara sagrada was used by Native Americans for centuries, and was accepted into medical practice in the United States in 1877, and by 1890 had replaced the berries of the European buckthorn (R. cathartica) as a commonly used laxative. It was the principal ingredient in many commercial, over-the-counter laxatives in North American pharmacies until 9 May 2002, when the U.S. Food and Drug Administration issued a final rule banning the use of aloe and cascara sagrada as laxative ingredients in over-the-counter drug products. Use of cascara sagrada has been associated with abdominal pain and diarrhea; it is also potentially carcinogenic.
In July 2003, the FDA responded to a citizen's petition filed against the May 2002 final ruling banning the use of cascara sagrada in OTC laxatives. by the American Herbal Products Association (AHPA) and International Aloe Science Council (IASC) (June 2002, CP25) Subsequent data submissions occurred in October 2002 (SUP14) and December 2002 (SUP15)). Upon further evaluation of all submitted information, the FDA found inadequate support for the petition that cascara sagrada should be generally recognized as safe and effective for OTC use as a laxative.
In September 2003, the FDA also responded to a petition (CP27) that was filed in August 2002 in which the FDA stated that "the agency does not find that the benefits of using cascara sagrada laxative ingredients outweigh the risks" and that the data contained in petition CP27 "do not rule out the possibility that cascara sagrada preparations are genotoxic and/or carcinogenic".
The fruit can also be eaten cooked or raw, but has a laxative effect. The food industry sometimes uses cascara as a flavoring agent for liquors, soft drinks, ice cream, and baked goods. Cascara honey is tasty, but slightly laxative. The wood is used by local people for posts, firewood, and turnery. It is also planted as an ornamental, to provide food and habitat for wildlife, or to prevent soil erosion. Due to its bitter taste, cascara can be used to stop nail-biting by applying it to the fingernails.
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|Wikisource has the text of the 1905 New International Encyclopedia article Cascara Sagrada.|