By Michael T. Murray, N.D.

Introduction
Cat's claw (Uncaria tomentosa) is one of the most interesting medicinal plants of South America. The Spanish called the plant Uña de Gato (cat's claw), because the plant's hooks resemble that of a cat's claw. In traditional Peruvian medicine, the root of cat's claw has been used for a variety of ailments and applications including, arthritis, asthma, cancer, peptic ulcers, infections, and wound healing. Preliminary studies seem to support this traditional use.

Although cat's claw preparations have been available in the United States since the early 1990s, its popularity and reputation has been somewhat tainted by the marketing of products composed of preparations from the wrong part of the plant, a lack of active compounds, and other problems of poor quality control.

The premier cat's claw preparation in the world is Saventaro®. This commercial product of Austria is the result of over 25 years of research led by the noted scientist Klaus Keplinger. It is the only cat's claw preparation that has been extensively studied and patented.[1]

How is Saventaro® different from other cat's claw products?
There are several important differences. First of all, there are two species of plant called cat's claw in Peru - Uncaria tomentosa and Uncaria guianensis. However, Uncaria tomentosa is the species most valued for its medicinal effects. The next problem is that the chemical composition of Uncaria tomentosa can vary from plant to plant depending on where it is grown, the environment, and soil conditions.[2] If a cat's claw root is high in pentacyclic alkaloids and low in tetracyclic alkaloids it will be much more active on the immune system than a root that is high in tetracyclic alkaloids. That is because the pentacyclic alkaloids are the compounds that appear to be responsible for the majority of the beneficial effects of cat's claw on the immune system.[1] The tetracyclic alkaloids block or antagonize these effects of pentacyclic alkaloids. It is, therefore, very important to analyze samples of the root for chemical constituents prior to harvesting. Although there are more than 50 different cat's claw products in the United States, only Saventaro® has been cultivated, harvested, and extracted in such a manner as to contain only the beneficial pentacyclic alkaloids.[3]

Product	Pentacyclic alkaloids	Tetracyclic alkaloids
Product A	20%	80%
Product B	62%	38%
Product C	69%	31%
Saventaro®	100%	less than 0.05%

What scientific research has been done on cat's claw?
Most of the recent scientific research on cat's claw has focused on the effects of various pentacyclic alkaloids and other constituents on the immune system - including clinical studies in immune system related conditions. Some of the effects noted in test tube studies with pentacyclic alkaloids include a powerful effect on phagocytosis - the process by which certain white blood cells engulf and destroy foreign particles including bacteria, viruses, cancer cells, and cellular debris.[1,3] Pentacyclic alkaloids also appear to be the factors responsible for any wound healing effects.[4] Researchers are also looking at the effects of non-alkaloid compounds in cat's claw including substances that had never been found in nature before. One compound in particular, a quinovic acid glycoside, has been found to possess significant anti-inflammatory properties and some antiviral properties as well.[5,6]

Can cat's claw fight infection?
Apparently. The combination of activating the immune system and possibly exerting some antiviral effects suggests cat's claw may be helpful in preventing and treating viral infections. Saventaro® has been shown to boost immune function in people who have a tendency to recurrent colds and flu-like infections (especially the elderly) as well in people who suffer from herpes virus outbreaks.[7] Saventaro® has also been the subject of several preliminary studies in people with HIV infection. The initial data is promising in that some of the test subjects taking Saventaro® demonstrated significant increases in helper T-cells and reduced viral loads. They also reported increased well-being, vitality, a better tolerance of anti-HIV drug therapy, and fewer opportunistic infections. These results will need to be confirmed in larger, better designed trials.

Since cat's claw can enhance immune function, should it be avoided in people with autoimmune diseases like rheumatoid arthritis?
No. In fact, Saventaro® was shown to produce significant improvement in rheumatoid arthritis in a double-blind study indicating that it should be considered supportive in autoimmune diseases.[7] Although there are no clinical studies to support it use in autoimmune conditions other than rheumatoid arthritis, there are documented case reports in people other autoimmune diseases. Hopefully, additional studies will clarify how beneficial cat's claw might be in these conditions.

The double-blind study in rheumatoid arhtritis was conducted at the University Hospital of Innsbruck, Austria. The primary criteria of efficacy were the number of tender and swollen joints judged by both the physician and the patient. The rating of joint pain by the patient and blood measurements indicating disease activity were also recored. At the end of the 24 week study, the number of tender joints and the blood measurement of the rheumatoid factor was significantly lower in the Saventaro® group than in the placebo group. Compared to their initial ratings of pain, 17 of the 18 patients in the Saventaro® group had a decrease in joint pain. Of the seventeen patients in the Saventaro® group with a decrease in joint pain, 14 had a regression of at least 50% in the number of tender joints, ten of the patients a regression of at least 75% in joint pain, and in five of the patients the number of tender joints regressed completely. In contrast, in the placebo group only ten of the seventeen patients exhibited a decrease in the number of tender joints at 6 months.

What about allergies?
Allergies, like autoimmune diseases, are associated with an overactive immune system. Although there are no clinical studies with cat's claw in allergic disorders, there have been a series of individual case reports with Saventaro® indicating potential benefit in asthma and hayfever.[7]

What about using cat's claw in cancer?
Given the seriousness of cancer and the lack of scientific studies on cat's claw, it cannot be recommended as a primary therapy of cancer. It can, however, be used as a supportive therapy in individuals undergoing conventional anticancer therapies. Cat's claw does not appear to interfere with the action of chemotherapy agents or radiation. Physicians in Austria have reported that use of Saventaro® results in a marked increase in quality of life and better tolerability of radiation and chemotherapy. In particular they report a reduction in chemotherapy-induced nausea, a reduction in the fall in blood pressure values following acute treatment, shortening of the recovery phases between individual treatment cycles and a reduction in susceptibility to infection.[7]

What is the proper dosage of cat's claw?
The dosage of Saventaro® is one 20 mg capsule three times daily for the first 10 days and one capsule daily thereafter.

Is cat's claw safe?
Cat' claw is generally regarded as being quite safe and toxicity studies in animals have confirmed this safety.[1] However, because its effects during pregnancy and lactation have not been sufficiently studies, it is generally advised that it should not be taken by women planning a pregnancy, or who are pregnant, or breast-feeding. Because it may enhance certain aspects of immune function, it should also be avoided in people scheduled for an organ transplant or skin-graft, since an activated immune system can lead to rejection of transplanted cells.[8]

References:

1. Keplinger K, Laus G, Wurm M, et al.: Uncaria tomentosa (Wild.) DC. Ethnomedicinal use and new pharmacological, toxicological and botanical results. J Ethnopharmacol 64:23-34, 1999.
2. Laus G, Brossner D, Keplinger K. Alkaloids of Peruvian Uncaria tomentosa. Phytochemistry 45:855-60, 1997.
3. KeplingerK, Keplinger D. Oxindole alkaloids having properties stimulating the immunologic system and preparation containing the same. United States Patent #5,302,611. April 12 1994.
4. Wurm M, Kacani L, Laus G, Keplinger RK, Dierich MP: Pentacyclic oindole akaloids from Uncaria tomentosa induce human endothelial cells to release a lymphocyte proliferation-regulating factor. Planta Medica 64:701-704, 1998.
5. AquinoR, De Simone F, Pizza C, et al.: Plant metabolites. Structure and in vitro antiviral activity of quinovic acid glycosides from Uncaria tomentosa and Guettarda platypoda. J Natural Products 52: 679-685, 1989.
6. AquinoR, de Feo V, de Simone R, et al.: Plant metabolites. New compounds and anti-inflammatory activity of Uncaria tomentosa. J Natural Products 54: 453-459, 1991.
7. Summary and Assessment of Clinical Examinations of KRALLENDORN(r) Products (Radix Uncariae tomentosae (Willd.) DC mod. pent). IMMODAL Pharmaka GmbH, Volders, Austria, 1999.
8. Schauss A: Cat's claw. Nat Med J 1:16-9, 1998.