For centuries, people have turned to psyllium, cascara sagrada, and senna to provide relief from constipation. These plant-based laxatives, available in health food stores and pharmacies, can help during those times when even eating plenty of fiber, drinking plenty of liquid, and exercising regularly haven’t helped you avoid this annoying problem.
However, because constipation can be a sign of a more serious health condition, laxatives should be used only with a health-care provider’s guidance if you are taking prescription drugs or are allergic to medications, are pregnant or diabetic, have abdominal pain or have recently had abdominal surgery, or have noticed a dramatic change in your bowel habits.
Psyllium, including the seeds and husks, is derived from three annual species of Plantago (plantains). P. ovata, native to the Mediterranean, North Africa, and western Asia, is widely grown in India and Pakistan. P. psyllium and P. indica (both also known as P. arenaria) are native to the Mediterranean region and grown commercially in Spain and southern France.
In older references, psyllium is referred to as P. ispaghula. Use of psyllium seed comes to us in part from Persian traditions of a thousand years ago. In Persian, ispaghul means “ear of a horse”: the seeds, 1/8-inch long ovals with a distinct depression in the center, resemble horses’ ears.
Psyllium seeds are a common ingredient in bulk-forming laxatives, which have a mechanism of action similar to the body’s normal process of evacuating the bowels. Psyllium seeds and husks are high in mucilage and, when soaked in water, swell to many times their original volume. Psyllium thus increases the volume of the intestinal contents, stretching and lubricating the gut wall and encouraging wastes to move through the colon.
A typical daily dose is 2 teaspoons of powdered seeds or 1 teaspoon of husks stirred into a large glass of water and taken immediately (before it thickens) 30 minutes to an hour after a meal. Follow the label instructions on commercial bulk-forming laxatives.
Although psyllium is a relatively gentle laxative, the seeds and husks are known to produce rare allergic reactions and can be dangerous in cases of intestinal obstruction. See your doctor if constipation persists.
Cascara sagrada, or “sacred bark”, is the dried, aged bark of Rhamnus purshiana, a small tree in the buckthorn family native to the Pacific Northwest. The bark is mainly wild-harvested in Oregon, Washington, and southern British Columbia. Although ingesting fresh bark can cause nausea and intense cramping, the bark when dried and aged is generally considered safe to use as a laxative.
Few plants of western North America have been included in official drug compendiums such as the U.S. Pharmacopoeia; cascara sagrada is one of a handful to reach “official” status and one of the very few American medicinal plants introduced into regular medical practice since 1880.
Cascarosides A and B, compounds found in the dried bark of cascara sagrada, are responsible for causing muscular contractions in the large intestine, which assist in bowel movements. The usual dose is 1 ml or 20 drops of fluid extract; follow label instructions. Large doses or long-term use of the bark may cause inflammation of the colon, chronic diarrhea, and weakness due to excessive potassium loss. A physician friend says he can tell when a patient has been abusing cascara because the colon’s mucous lining is stained dark. In itself, this is considered reversible and harmless but probably indicates inappropriate use of the laxative.
Using senna leaves and pods as laxatives comes to us from the Arabian physicians of the eighth century. Several kinds of senna are used, including Alexandrian senna and Tinnevelley senna, which are now considered to be a single species, Senna alexandrina. These members of the pea family, native to Europe and Asia, are cultivated commercially in the Middle East and India. Tinnevelley senna is the kind most widely used in the United States.
Senna works much like cascara, but is considered stronger. The leaves and pods contain anthraquinones, which stimulate and increase the movements of the colon while increasing the water and electrolyte content of the stool.
Senna leaves are considered safer to use than the pods, which contain twice the amount of active compounds found in the leaves. Senna is less expensive than cascara but is more likely to cause cramping.
Senna should not be used for more than a week at a time. Longer use can cause dependency; the bowels can become chronically sluggish from reliance on it. Senna abuse can lead to fluid and electrolyte imbalances, which could reduce the effectiveness of prescribed heart medications. Pregnant and nursing women should not use senna.
• ESCOP. Proposal for European Monographs Vol. 2, Bevrijdingslaan, The Netherlands: ESCOP Secretariat, 1992.
• Leng-Preschlow, E. (ed.). Pharmacology 1992, 44(S1):1–52.
• Sprecher, D. L., et al. Annals of Internal Medicine 1993, 119(7): 545–555.
• Tyler, V.E., et al. Pharmacognosy. 9th ed. Philadelphia: Lea & Febiger, 1988.
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