Cat's claw is a large woody vine indigenous to the Amazon rain forest of South America. The herb earns its name from the curved thorns on the vine that resemble the claws of a cat. Also known by its Spanish equivalent uña de gato, cat's claw has a long history of use as a folk medicine by native peoples to treat intestinal complaints, asthma, wounds, cancer , tumors, arthritis, inflammations, diabetes, irregularities of the menstrual cycle, fevers, ulcers, dysentery, and rheumatism. They have also utilized the herb as a kidney cleanser, blood cleanser, and contraceptive.
Two species of cat's claw are found in the rain forest: Uncaria tomentosa and Uncaria guianensis. Although these species are similar in appearance and have been used in many of the same ways, research on Uncaria tomentosa has revealed it to be more valuable as a therapeutic agent.
Cat's claw has been called one of the most important botanical herbs found in the rain forest and is used as a cleansing and supportive herb of the immune system, cardiovascular system, and intestinal system. Although research on cat's claw began in the 1970s, it didn't gain worldwide attention until the 1990s, when studies showed it to be a possible treatment for Acquired Immune Deficiency Syndrome (AIDS ) and Human Immunodeficiency Virus (HIV) infection; cancer; and other ailments. Cat's claw is reported to enhance immunity and heal digestive and intestinal disorders. It has been used to treat many other ailments including acne, allergies , arthritis, asthma, candidiasis, chronic fatigue , chronic inflammation, depression, diabetes mellitus , environmental toxicity and poisoning, Epstein-Barr virus (EBV), fibromyalgia, hemorrhoids , herpes, hypoglycemia, systemic lupus erythematosus (SLE), menstrual disorders and hormone imbalances, parasites, premenstrual syndrome (PMS), tumors, upper respiratory infections , viral infections, and wounds.
One unfortunate side effect of recent interest in cat's claw has been its virtual extinction in parts of the rain forest. According to the Herb Research Foundation, the government of Peru has had to outlaw the export of all wild cat's claw plants. Almost all cat's claw root and bark used for commercial preparations as of 2003 comes from cultivated plants.
Although the stem bark of cat's claw has some medicinal activity, the root is three to four times more active than the stem bark. The strength of the active components in cat's claw is quite variable; it depends on the time of year that the plant is harvested.
The active compounds in cat's claw include alkaloids, triterpenes, phytosterols, and proanthocyanidins. Researchers have isolated unique alkaloids in the bark and roots that activate the immune system by increasing white blood cell activity. Rynchophylline, one of the alkaloids isolated from cat's claw, has antihypertensive properties that may be beneficial in lowering the risk of strokes and heart attacks by reducing heart rate, lowering blood pressure, increasing circulation, and lowering blood cholesterol levels.
Researchers have also discovered substances in cat's claw that have antitumor, antileukemic, antioxidant, antimicrobial, antibacterial, anti-inflammatory, antiviral, and diuretic properties. Dr. Brent W. Davis has studied cat's claw for a number of years and has described it as "the opener of the way" in reference to its ability to treat many bowel, stomach, and intestinal complaints including diverticulitis , leaky and irritable bowel syndromes, gastritis , ulcers, hemorrhoids, Crohn's disease , and colitis.
Cat's claw's anti-inflammatory actions have been effective in relieving the stiffness and swelling prevalent in arthritis, rheumatism, and joint pain . An Austrian study published in 2002 found that cat's claw significantly reduced joint tenderness and swelling in a sample of 40 patients with rheumatoid arthritis , with only minor side effects and no interactions with the patients' other arthritis medications. A recent study done in Peru indicates that the anti-inflammatory effects of cat's claw are stronger in extracts made with alcohol than in water-based solutions.
Studies of the therapeutic benefits of cat's claw on cancer have produced several interesting findings. Cat's claw's immunostimulating properties have been shown to enhance the function of white blood cells to attack and digest carcinogenic substances and harmful microorganisms that may inhibit the growth of cancer cells and tumors. Used as an adjunct treatment to chemotherapy and radiation, cat's claw has shown promise in diminishing side effects of hair loss, nausea , skin problems, infections, and weight loss.
Clinical studies have tested Krallendon, an immune-boosting extract of cat's claw, in the treatment of AIDS patients and persons who are HIV-positive, either as a single treatment or in conjunction with the AIDS drug azidothymidine (AZT). Results showed that Krallendon was able to deter the reproduction of the AIDS virus, stop growth of cancerous cells, and activate the immune system. In addition, painful side effects resulting from the AZT treatment were diminished. Cat's claw's antioxidant properties help protect cells from environmental substances such as smoke, pesticides, pollution, alcohol, x rays, gamma radiation, ultraviolet light, rancid food, and certain fats. The herb also helps prevent the spread of free radicals, protecting cells from mutating and developing into tumors.
Cat's claw is available in health food stores and herb shops in several forms: dry extract, crushed bark, capsule, tablet, tea, and tincture.
To prepare the tea, boil 1 g (0.4 oz) of the bark in 1 cup of water for 10–15 minutes. Strain the mixture before drinking. A suggested dose is one cup of tea three times daily.
Tincture dosage: 1–2 ml up to two times daily. Children over two years of age and adults over 65 should begin use with mild doses and increase strength gradually if needed.
Cat's claw is not recommended for pregnant or nursing women or for women who are trying to conceive. Children under the age of two should not take cat's claw. Persons with a health condition should consult a qualified herbalist before taking cat's claw.
European studies have reported low toxicity in the use of cat's claw, even when taken in large doses. The only noted side effect was diarrhea . In 2001, however, one case study was reported from South America of a patient with lupus developing kidney failure after taking cat's claw extracts.
Cat's claw should not be combined with hormonal drugs, insulin, or vaccines. It may also cause the immune system to reject foreign cells. Persons who have received organ or tissue transplants should not use this herb. The dosage may need to be reduced when taken with other herbs.
Cat's claw has also been reported to potentiate, or intensify, the effects of antihypertensives (medications given to control high blood pressure). Persons taking such drugs should use cat's claw only on the advice of a physician.
Elkins, Rita. Cat's Claw (Una de Gato): Miracle Herb from the Rain Forest of Peru. Woodland Publishing, 1996.
Jones, Kenneth. Cat's Claw: Healing Vine of Peru. Sylvan Press, 1995.
Steinberg, Phillip N. Cat's Claw: The Wondrous Herb from the Peruvian Rainforest. Healing Wisdom Publications, 1996.
Aguilar, J. L., P. Rojas, A. Marcelo et al. "Anti-Inflammatory Activity of Two Different Extracts of Uncaria tomentosa (Rubiaceae)" Journal of Ethnopharmacology 81 (July 2002): 271-276.
Blumenthal, Mark. "Una de Gato (Cat's Claw) Rainforest Herb Gets Scientific and Industry Attention." Whole Foods (October 1995): 62, 62, 66, 68, 78.
Craig, Winston J. "A Closer Look at Cat's Claw." (Herb Watch). Vibrant Life 18 (September-October 2002): 38-39.
Mur, E., F. Hartig, G. Eibl, and M. Schirmer. "Randomized Double-Blind Trial of an Extract from the Pentacyclic Alkaloid-Chemotype of Uncaria tomentosa for the Treatment of Rheumatoid Arthritis." Journal of Rheumatology 29 (April 2002): 678-681.
Herb Research Foundation. 1007 Pearl St., Suite 200, Boulder, CO 80302. (303) 449-2265. <www.herbs.org>.
Rebecca J. Frey, PhD