Although Cat’s Claw (or “una de gato”) is generally thought of as only coming from the rainforests of Peru, it is also found in the rainforests of surrounding countries such as Brasil and Bolivia. It has numerous traditional medicine uses, along with the popular uses today of immune system stimulation/modulation. It is known to possess antioxidant and anti-inflammatory activity, and has been used for numerous illnesses such as cancer, AIDS, colds/flu, yeast infections, intestinal/gastric ulcers and both osteo- and rheumatoid arthritis.
A lively debate exists for which chemotype (eg. containing pentacyclic or tetracyclic oxindole alkaloids) of cat’s claw and which species “is the best”. A recent preclinical study using in vitro methods by Sandoval et al (2002) concluded that although both species show antioxidant and anti-inflammatory effects, the presence of oxindole or pentacyclic alkaloids did not influence these activities. Sandoval et al (2002) further concluded that U.guianensis is more potent in these activities. Saventaro is the brand name of a cat’s claw extract that contains the pentacyclic oxindole alkaloids (manufactured by an Austrian company, Immodal Pharmaka).
Another debate exists as to which part of the plant is the most efficacious. Although many references have been made to the use of the root bark traditionally, today the stem bark is more popular, mostly due to its availability and higher sustainability of harvest.
Recent animal studies on a proprietary extract of cat’s claw called C-Med 100 have found that it has the ability to increase spleen cell numbers dose-dependently, but the effect was not due to increasing proliferation rate but rather their survival rate. Thus the authors noted the possible use of this extract for patients with leukopenia (Akesson et al., 2003).
An extract of the pentacyclic chemotype of U. tomentosa was studied in 40 rheumatoid arthritis patients (also taking sulfasalazine or hydroxychloroquine) for its safety and efficacy. The study design was a 52-week 2-phase study, with the first phase consisting of 24 weeks and being double-blind and placebo-controlled, and the second phase consisting of 28 weeks with all patients taking the cat’s claw treatment. In the first phase of the study the treatment group showed a statistically significant reduction in number of painful joints compared to the placebo group. In the second phase of the study, treatment resulted in a reduction in the number of painful and swollen joints, and in the Ritchie Index compared to the post-treatment values. Minor side effects were observed and the treatment was concluded to be relatively safe and of modest benefit (Mur et al., 2002).
Cat’s claw was studied for its effect in patients with osteoarthritis of the knee, safety and for its in-vitro antioxidant and anti-inflammatory actions. In 45 patients with osteoarthritis of the knee, freeze-dried U.guianensis was given to 30 and placebo to 15, and hematological parameters were studied. No negative effects were found on the blood, liver, or experienced side effects compared to placebo. Symptoms that were significantly reduced by treatment were pain associated with activity and medical and patient assessment scores. However, no changes were found in knee pain at rest, at night, and knee circumference. In vitro studies of antioxidant (using the DPPH free radical scavenging method) and anti-inflammatory (measuring TNFalpha, and PGE2 production) activity showed both species to be equally efficacious. Due to the dosages studied, it was hypothesized that anti-inflammatory activity may result more from ability to inhibit TNFalpha rather than PGE2 (Piscoya et al, 2001).
The proprietary cat’s claw extract called C-MED 100 was studied for its ability to affect the response to 23 valent pneumococcal vaccine. C-MED 100 had been earlier found in preclinical studies to produce immune stimulating and anti-inflammatory effects. C-MED was concluded to enhance the immune response through observed lymphocyte/neutrophil ratios of peripheral blood, and the reduction of decline of antibody titer responses to the pneumococcal vaccination at 5 months. No negative side effects were found either through medical examination, clinical chemistry or blood cell analysis (Lamm et al., 2001).
In a preliminary study, a decoction of U.tomentosa bark was given to a smoker for 15 days and found to decrease the mutagenicity induced by Salmonella typhimuriium TA98 and TA100 through urine analysis. Fractions of the plant extract were tested in vitro and found to have no mutagenic effect in strains of S. typhimurium, bur rather to be able to protect against photomutagenic effects of 8-mehoxy-psoralen and UVA. These studies confirmed earlier reports of antimutagenic activity of cat’s claw, but not of its proported mutagenic effects (Rizzi et al., 1993).
Safety / Dosage
Generally dosage ranges from 20-60 mg daily for a week, and then 20 mg daily as a maintenance dose. The standardized product containing pentacyclic oxindole alkaloids (POAs) that is manufactured by Immodal Pharmaka (Saventaro) is standardized to contain a minimum of 260 µg POAs in every 20 mg dose. The C-MED-100 product (manufactured by CampaMed) is manufactured to eliminate the indole alkaloids (<0.05%) and other high molecular weight compounds such as tannins, and to contain 8% or more carboxyl alkyl esters. The recommended dose of this product is 350 mg daily (McKenna et al., 2002).
Cat’s claw is generally regarded as safe, but it is not recommended for pregnancy or lactation because it has not been fully evaluated. Initial and temporary gastrointestinal side effects are sometimes experienced, such as gas, bloating, nausea and diarrhea.
1.Akesson Ch, Pero RW, Ivars F. C-Med 100, a hot water extract of Uncaria tomentosa, prolongs lymphocyte survival in vivo. Phytomedicine. 2003 Jan;10(1):23-33.
2.Lamm S, Sheng Y, Pero RW. Persistent response to pneumococcal vaccine in individuals supplemented with a novel water soluble extract of Uncaria tomentosa, C-Med-100. Phytomedicine. 2001 Jul;8(4):267-74.
3.McKenna D, Jones K, Hughes K, Humphrey S. Botanical Medicines: The Desk Reference for Major Herbal Supplements, 2nd Ed. 2002 Haworth Press; Binghamton, NY
4.Mur E, Hartig F, Eibl G, Schirmer M. Randomized double blind trial of an extract from the pentacyclic alkaloid-chemotype of uncaria tomentosa for the treatment of rheumatoid arthritis. J Rheumatol. 2002 Apr;29(4):678-81.
5.Piscoya J, Rodriguez Z, Bustamante SA, Okuhama NN, Miller MJ, Sandoval M. Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species Uncaria guianensis. Inflamm Res. 2001 Sep;50(9):442-8.
6.Rizzi R, Re F, Bianchi A, De Feo V, de Simone F, Bianchi L, Stivala LA. Mutagenic and antimutagenic activities of Uncaria tomentosa and its extracts. J Ethnopharmacol. 1993 Jan;38(1):63-77.
7.Sandoval M, Okuhama NN, Zhang XJ, Condezo LA, Lao J, Angeles' FM, Musah RA, Bobrowski P, Miller MJ. Anti-inflammatory and antioxidant activities of cat's claw (Uncaria tomentosa and Uncaria guianensis) are independent of their alkaloid content. Phytomedicine. 2002 May;9(4):325-37.
EDITOR'S NOTE: This monograph can be found in The Health Professional's Guide to Dietary Supplements (Lippincott, Williams & Wilkins) by Shawn M. Talbott, PhD and Kerry Hughes, MS.