Cat’s claw (U. tomentosa) is a large, woody vine that derives its name from hook-like thorns that grow along the vine and resemble the claws of a cat. Two closely related species of Uncaria are used almost interchangeably in the rainforests: U. tomentosa and U. guianensis. Both species can reach over 30 m high into the canopy. U. tomentosa has small, yellowish-white flowers, whereas U. guianensis has reddish-orange flowers and thorns that are more curved. Cat’s claw is indigenous to the Amazon rainforest and other tropical areas of South and Central America, including Peru, Colombia, Ecuador, Guyana, Trinidad, Venezuela, Suriname, Costa Rica, Guatemala, and Panama.
There are other species of plants with a common name of cat’s claw (or uña de gato) in Mexico and Latin America; however, they are entirely different plants, not belonging to the Uncaria genus, or even the Rubiaceae family. Several of the Mexican uña de gato varieties have toxic properties.
TRIBAL AND HERBAL MEDICINE USES
Both South American Uncaria species are used by the indigenous peoples of the Amazon rainforest in very similar ways and have long histories of use. Cat’s claw (U. tomentosa) has been used medicinally by the Aguaruna, Asháninka, Cashibo, Conibo, and Shipibo tribes of Peru for at least 2,000 years. The Asháninka Indian tribe in central Peru has the longest recorded history of use of the plant. They are also the largest commercial source of cat’s claw from Peru today. The Asháninka use cat’s claw to treat asthma, inflammations of the urinary tract, arthritis, rheumatism, and bone pain; to recover from childbirth; as a kidney cleanser; to cure deep wounds; to control inflammation and gastric ulcers; and for cancer. Indigenous tribes in Piura use cat’s claw to treat tumors, inflammations, rheumatism, and gastric ulcers. Other Peruvian indigenous tribes use cat’s claw to treat diabetes, urinary tract cancer in women, hemorrhages, menstrual irregularity, cirrhosis, fevers, abscesses, gastritis, rheumatism, tumors, and inflammations as well as for internal cleansing and to “normalize the body.” Reportedly, cat’s claw has also been used as a contraceptive by several different tribes of Peru (but only in very large dosages). Dr. Fernando Cabieses, M.D., a noted authority on Peruvian medicinal plants, explains that the Asháninka boil 5 to 6 kg (about 12 pounds) of the root in water until it is reduced to little more than 1 cup. This decoction is then taken 1 cup daily during the period of menstruation for three consecutive months; this supposedly causes sterility for three to four years.
Cat’s claw has been used in Peru and Europe since the early 1990s as an adjunctive treatment for cancer and AIDS as well as for other diseases that target the immune system. In herbal medicine today, cat’s claw is employed around the world for many different conditions, including immune disorders, gastritis, ulcers, cancer, arthritis, rheumatism, rheumatic disorders, neuralgias, chronic inflammation of all kinds, and such viral diseases as herpes zoster (shingles). Dr. Brent Davis, D.C. has written several articles on cat’s claw and refers to it as the “opener of the way” for its ability to cleanse the entire intestinal tract and its effectiveness in treating stomach and bowel disorders (such as Crohn’s disease, leaky bowel syndrome, ulcers, gastritis, diverticulitis, and other inflammatory conditions of the bowel, stomach, and intestines). Dr. Julian Whitaker, M.D. reports using cat’s claw for its immune-stimulating effects, for cancer, to help prevent strokes and heart attacks, to reduce blood clots, and for diverticulitis and irritable bowel syndrome.
PLANT CHEMICALS
Cat’s claw has several groups of plant chemicals that account for much of the plant’s actions and uses. First and most studied is a group of oxidole alkaloids that has been documented with immune-stimulant and antileukemic properties. Another group of chemicals called quinovic acid glycosides have documented anti-inflammatory and antiviral actions. Antioxidant chemicals (tannins, catechins and procyanidins) as well as plant sterols (beta-sitosterol, stigmasterol, and campesterol) account for the plant’s anti-inflammatory properties. A class of compounds known as carboxyl alkyl esters found in cat’s claw has been documented with immunostimulant, anti-inflammatory, anticancerous, and cell-repairing properties.
Cat’s claw contains ajmalicine, akuammigine, campesterol, catechin, carboxyl alkyl esters, chlorogenic acid, cinchonain, corynantheine, corynoxeine, daucosterol, epicatechin, harman, hirsuteine, hirsutine, iso-pteropodine, loganic acid, lyaloside, mitraphylline, oleanolic acid, palmitoleic acid, procyanidins, pteropodine quinovic acid glycosides, rhynchophylline, rutin, sitosterols, speciophylline, stigmasterol, strictosidines, uncarine A thru F, and vaccenic acid.
BIOLOGICAL ACTIVITIES AND CLINICAL RESEARCH
With so many documented traditional uses of this important rainforest plant, it is not surprising that it came to the attention of Western researchers and scientists. Studies began in the early 1970s when Klaus Keplinger, a journalist and self-taught ethnologist from Innsbruck, Austria, organized the first definitive work on cat’s claw. Keplinger’s work in the 1970s and 1980s led to several extracts of cat’s claw being sold in Austria and Germany as herbal drugs, as well as the filing of four U.S. patents describing extraction procedures for the immune-stimulating oxindole alkaloids. These novel oxindole alkaloids fueled worldwide interest in the medicinal properties of this valuable vine of the rainforest. Other independent researchers in Spain, France, Japan, Germany, and Peru followed Keplinger, many of them confirming his research on the immunostimulating alkaloids in the vine and root. Many of these studies published from the late 1970s to early 1990s indicated that the whole oxindole alkaloid fraction, whole vine bark and/or root bark extracts, or six individually-tested oxindole alkaloids, when used in relatively small amounts, increased immune function by up to 50%. These study results were substantiated by Canadian researchers at the University of Ottawa (1999) and by Peruvian researchers (1998), both working with whole vine extract.
Proprietary extracts of cat’s claw have been manufactured since 1999, and clinical studies, funded by the manufacturers of these extracts, have been published showing that these cat’s claw products continue to provide the same immune-stimulating benefits as has been documented for almost 20 years.
But then facts concerning cat’s claw’s benefits became confusing, as often happens with market-driven research. A manufacturer of a cat’s claw extract funded a test tube study about these immune-stimulating alkaloids. The research indicated that, supposedly, two different types (chemotypes) of cat’s claw vines are growing in the rainforest, and/or that cat’s claw produces “good alkaloids” and “bad alkaloids.” It has coined the “good ones” pentacyclic (POA) alkaloids and the “bad ones” tetracyclic (TOA) alkaloids; both are oxindole alkaloids. The research and marketing attempts to suggest that one set of “bad alkaloids” counteracts the immune benefits of the “good alkaloids.”
This research has not been confirmed by independent researchers - that is, those who are not selling cat’s claw or being paid by companies selling cat’s claw. This research has also not been confirmed in humans or animals. This market-driven research would seek to discount or disprove all the definitive, independent research done over the last three decades in Japan, Peru, Germany, Spain, and the United States (including the four U.S. patents filed by these same researchers). Much of the previous independent research was performed on whole oxindole extracts and whole root or vine extracts (some in humans and animals). This research documented the presence of both types of alkaloids, both of which showed immune stimulant actions. Indeed, some of the “new research” refuted the marketer’s original (and independently confirmed) findings! As for the possibility of a “new chemotype”: a plant doesn’t change its chemical constituency in five years. Again, two species of cat’s claw exist - U. tomentosa and U. guianensis; they have a similar chemical makeup but a different ratio of oxindole alkaloids. Admittedly U. tomentosa has declined in the Peruvian rainforest because of overharvesting in the last five to eight years. The lower growing and easier-to-find U. guianensis variety is a common “adulterant” in many large lots of cat’s claw bulk material being exported out of South America today.
In addition to its immunostimulating activity, in vitro anticancerous properties have been documented for these alkaloids and other constituents in cat’s claw. Five of the oxindole alkaloids have been clinically documented with in vitro antileukemic properties, and various root and bark extracts have demonstrated antitumorous and anticancerous properties. Italian researchers reported in a 2001 in vitro study that cat’s claw directly inhibited the growth of a human breast cancer cell line by 90%, while another research group reported that it inhibited the binding of estrogens in human breast cancer cells in vitro. Swedish researchers documented it inhibited the growth of lymphoma and leukemia cells in vitro in 1998. Early reports on Keplinger’s observatory trials with cancer patients taking cat’s claw in conjunction with such traditional cancer therapies as chemotherapy and radiation reported fewer side effects to the traditional therapies (such as hair loss, weight loss, nausea, secondary infections, and skin problems). Subsequent researchers have shown how these effects might be possible: they have reported that cat’s claw can aid in DNA cellular repair and prevent cells from mutating; it also can help prevent the loss of white blood cells and immune cell damage caused by many chemotherapy drugs (a common side effect called leukopenia).
Another significant area of study has focused on cat’s claw’s anti-inflammatory properties. While plant sterols and antioxidant chemicals found in cat’s claw account for some of these properties, new and novel plant chemicals called quinovic acid glycosides were documented to be the most potent anti-inflammatory constituents of the plant. This study and subsequent ones indicated that cat’s claw (and, especially, its glycosides) could inhibit inflammation from 46% up to 89% in various in vivo and in vitro tests. The results of these studies validated its long history of indigenous use for arthritis and rheumatism, as well as for other types of inflammatory stomach and bowel disorders. It was also clinically shown to be effective against stomach ulcers in an in vivo rat study.
Research in Argentina reports that cat’s claw is an effective antioxidant; other researchers in 2000 concluded that it is an antioxidant as well as a remarkably potent inhibitor of tumor necrosis factor (TNF) alpha production. TNF represents a model for tumor growth driven by an inflammatory cytokine chemical. Other researchers in the United States reported in 2002 that the anti-inflammatory actions of cat’s claw are not attributable to immunostimulating alkaloids but rather to another group of chemicals called carboxyl alkyl esters. This would explain why a product comprised of mostly alkaloids showed only modest benefit to arthritis patients in a study by another group that was incidentally selling a special alkaloid preparation of cat’s claw. The same group of anti-inflammatory glycoside chemicals also demonstrated in vitro antiviral properties in another earlier study.
In addition to the immunostimulant alkaloids, cat’s claw contains the alkaloids rhynchophylline, hirsutine, and mitraphylline, which have demonstrated hypotensive and vasodilating properties. Rhynchophylline has shown to prevent blood clots in blood vessels, dilate peripheral blood vessels, lower the heart rate, and lower blood levels of cholesterol. Some of the newer research indicates that cat’s claw might be helpful to people with Alzheimer’s disease; this could be attributable to the antioxidant effects already confirmed or, possibly, to the dilation of peripheral blood vessels in the brain by alkaloids such as rhynchophylline.
Another research group recently reported that cat’s claw’s immune-stimulating alkaloids pteropodine and isopteropodine might have other properties and applications. They reported that these two chemicals have shown to have a positive modulating effect on brain neurotransmitters called 5-HT(2) receptors. These receptor sites are targets for drugs used in treating a variety of conditions, including depression, anxiety, eating disorders, chronic pain conditions, and obesity.
CURRENT PRACTICAL APPLICATIONS
Cat’s claw has grown quite popular in the natural products industry and is mostly taken today to boost immune function, as an all over tonic and preventative to stay healthy, for arthritis and inflammation, for bowel and colon problems, and as an complementary therapy for cancer. The most common forms used today are cat’s claw capsules and tablets, both of which have become widely available in most health food stores at reasonable prices. There are also newer (and more expensive) proprietary extracts of cat’s claw in tablets and capsules, some backed by research-albeit paid-for research.
A good-quality, natural cat’s claw vine bark with naturally occurring chemicals is the best value, money wise. It contains all the natural chemicals that nature provides in the proper ratio (including immune-stimulating alkaloids, anti-inflammatory glycosides, and antioxidant chemicals), without chemical intervention. Some invasive extraction and manufacturing techniques may only extract one particular type of chemical, or change the complex ratio of naturally occurring chemicals in the plant-which ignores the efficiency and synergy of the plant. Scientists do not fully know how all these complex chemicals work together in harmony. In fact, scientists are still discovering new and novel active chemicals in this plant, even after 20 some-odd years of research on cat’s claw. As the market demand has increased for this rainforest plant over the last five years, more companies have gone into the business of harvesting it, and the quality of the bulk materials coming in from South America can be sometimes questionable. Oftentimes, a combination of U. tomentosa and U. guianensis is harvested and sold as “cat’s claw” (as, presently, the guianensis species is found more easily). Pick a good quality and trusted label and manufacturer for the best results and the best value.
| Main Preparation Method: decoction, fluid extract, or capsulesMain Actions (in order): immune stimulant, anti-inflammatory, antimutagenic (cellular protector), anticancerous, antiulcerousMain Uses:
Properties/Actions Documented by Research: Cautions: Do not use before or after an organ or bone marrow transplant since it boosts immune function. May also have a mild blood thinning effect. |
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Traditional Preparation: For general immune and prevention benefits, practitioners usually recommend 1 g daily of vine powder in tablets or capsules. Therapeutic dosages of cat’s claw are reported to be as high as 20 g daily and average 2-3 grams two or three times daily. Generally, as a natural aid for arthritis and bowel and digestive problems 3-5 g daily is recommended, if a good product is obtained. Alternatively, a standard vine bark decoction can be used much the same way indigenous people of the Amazon use it. The dosage for a standard decoction for general health and maintenance is 1/2-1 cup of a decoction once daily and up to 1 cup three times daily in times of special needs. Adding lemon juice or vinegar to the decoction when boiling will help extract more alkaloids and fewer tannins from the bark. Use about 1/2 teaspoon of lemon juice or vinegar per cup of water. For standardized and/or proprietary extract products, follow the label instructions.
Contraindications:
- Cat’s claw has been clinically documented with immunostimulant effects and is contraindicated before or following any organ or bone marrow transplant or skin graft.
- Cat’s claw has been documented with antifertility properties and is contraindicated in persons seeking to get pregnant. However, this effect has not been proven to be sufficient for the product to be used as a contraceptive, and it should not be relied on for such.
- Cat’s claw has chemicals that can reduce platelet aggregation and thin the blood. Check with your doctor first if you are taking coumadin or other blood-thinning drugs and discontinue use one week to ten days prior to any major surgical procedure.
- Cat’s claw vine bark requires sufficient stomach acid to help break down the tannins and alkaloids during digestion and to aid in absorption. Avoid taking bark capsules or tablets at the same time as antacids. Avoid taking high tannin (dark-colored) liquid extracts and tinctures directly by mouth and dilute first in water or acidic juice (such as orange juice).
- Large dosages of cat’s claw (3-4 gram dosages at a time) have been reported to cause some abdominal pain or gastrointestinal problems, including diarrhea (due to the tannin content of the vine bark) in some people. The diarrhea or loose stools tend to be mild and go away with continued use. Discontinue use or reduce dosage if diarrhea persists longer than three or four days.
Drug Interactions:
- Due to its immunostimulant effects, cat’s claw should not be used with medications intended to suppress the immune system, such as cyclosporin or other medications prescribed following an organ transplant. (This theory has not been proven scientifically.)
- Based upon in vivo rat studies, cat’s claw may protect against gastrointestinal damage associated with nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen.
- Cat’s claw may potentiate coumadin and blood-thinning drugs.
| Colombia | for dysentery, gonorrhea |
| French Guiana | for dysentery |
| Peru | for abscesses, AIDS, arthritis, asthma, blood cleansing, bone pains, cancer, cirrhosis, diabetes, diarrhea, disease prevention, dysentery, fevers, gastric ulcers, gastritis, gonorrhea, hemorrhages, herpes, immune disorders, inflammations, intestinal affections, menstrual irregularity, kidney cleansing, prostatitis, rheumatism, shingles, skin disorders, stomach disorders, ulcers problems, urinary tract disorders, tumors, wounds |
| Suriname | for dysentery, intestinal disorders, wounds |