Health Benefits of Cat's Claw

Can the traditional Amazonian remedy treat arthritis?

cat's claw (uncaria tomentosa)
Manfred Pfefferie/Oxford Scientific/Getty Images

Cat's claw (Uncaria tomentosa) is a woody vine native to the Amazon and Central American rainforests. Its name is derived from the hook-like thorns that resemble the claws of a cat. Cat’s claw bark and root have been used for centuries by South Americans as a remedy for arthritis and to treat digestive disorders such as gastritis, colitis, and stomach ulcers.

Cat's claw, also known by its Spanish name Uña de Gato, is sometimes referred to as the "life-giving vine of Peru." It should not be confused with cat's claw acacia, which contains a potentially poisonous cyanide compound.

Health Benefits

A number of early studies have suggested that cat’s claw has immune-modulating and antioxidant effects beneficial to the treatment of arthritis and other health conditions. Despite the expansiveness of these claims, there is little current evidence support its use.

This hasn't stopped consumers from buying the supplement, which ranked 25th in herbal remedy sales in 2000, according to the ABC Clinical Guide to Herbs.

Here is what some of the current research says:

Arthritis

Cat's claw contains a compound known as pentacyclic oxindolic alkaloid (POA) that is believed to have anti-inflammatory effects. The compound, specific to cat's claw, is able to block the production of inflammatory substances such as tumor necrosis factor-alpha (TNF-alpha).

TNF-a helps regulate the immune response and, among other things, is responsible for inducing fever, inflammation, and apoptosis (programmed cell death) in old or damaged cells.

An early study published in the Journal of Rheumatology found that people with rheumatoid arthritis who took a cat's claw extract for one year (along with their regular medications) had half as many painful joints as those provided a placebo.

Similar results were seen in people with osteoarthritis ("wear-and-tear arthritis"). According to a study published in Inflammation Research, a four-week course of cat's claw was able to reduce pain with activity in people with knee osteoarthritis better than with a placebo. What it did not reduce was either knee swelling or pain at rest.

Lyme Disease

A special type of cat's claw, known as samento, is believed to aid in the treatment of Lyme disease. Most of the evidence is based on test tube studies in which samento was better able to neutralize the causal bacteria (Borrelia burgdorferi) than the antibiotic doxycycline.

Proponents claim that samento is able to "boost" the immune system more effectively than regular cat's claw because it is devoid of a compound found called tetracyclic oxindole alkaloid (TOA) which is believed to inhibit POA.

Whether the same effect would be seen outside of the test tube is unknown. To date, the veracity of the health claims is largely unsupported, and there is little evidence that samento can either reduce the severity or shorten the duration of Lyme disease.

Cancer

Some early test tube studies have suggested that the POA found in cat's claw may have antitumor properties. It is believed that POA is toxic is specific cancers cells and may have less impact on the healthy cells typically damaged by chemotherapy.

A 2010 study from the University of Seville reported that POA derived from the bark of cat's claw was able to kill and prevent the spread of breast cancer and Ewing's sarcoma cells in test tube studies.

While the cytotoxic (cell-killing) effect was similar to that of the drug Cytoxan (cyclophosphamide), the dose needed to achieve this effect in humans would likely be unreasonable. Still, the finding hints at a promising new avenue for cancer drug development.

Possible Side Effects

Cat's claw may cause side effects in some people, including nausea, headache, dizziness, diarrhea, vomiting, and low blood pressure. Most cases resolve on their own once the treatment is stopped.

Cat's claw can also slow blood clotting, leading to easy bruising and bleeding (particularly in people on anticoagulants). Because of this, you should stop taking cat's claw at least two weeks before surgery to avoid excessive bleeding.

If you are taking any medications, speak with your doctor before using cat’s claw. Cat's claw is known to interact with many pharmaceutical drugs, including:

  • Allergy medications such as Allegra (fexofenadine)
  • Anticoagulants ("blood thinners")
  • Antifungals such as ketoconazole
  • Antiretrovirals used to treat HIV
  • Cancer drugs such as Taxol (paclitaxel)
  • Cholesterol medication such as lovastatin
  • Diuretics ("water pills")
  • Immune suppressants 
  • Oral contraceptives

Based on the belief that cat’s claw is an immune stimulant, the herb should not be used in organ transplant recipients and people with tuberculosis or autoimmune disorders (like multiple sclerosis, type 1 diabetes, or lupus). In situations like these, it is possible that cat's claws can trigger a relapse of symptoms or, in the case of organ transplants, lead to organ rejection.

Due to the lack of safety research, children, pregnant women, and nursing mothers should not use cat’s claw.

Dosage and Preparation

There is no guidance as to the appropriate use of cat's claw. Dosing recommendations vary by manufacturer and are guided more by current practices than by hard evidence.

Cat's claw supplements are generally sold in capsule and tincture formulations. The herb is also available in tea bags or purchased as loose "wild-crafted" powders and bark chips.

Capsule formulations are generally considered safe at doses of up to 350 milligrams daily. The dosing of cat's tinctures can vary by the strength of the formulation, but 1 to 4 milliliters daily is the most commonly recommended dose. As a rule of thumb, never take more than is recommended on the product label.

At this time, there is little scientific data on how long cat’s claw can be used safely. With that being said, published clinical trials lasting from four weeks to a year have been conducted with relatively few side effects.

What to Look For

Cat's claw, like other herbal supplements, are not subject to rigorous testing and research in the United States. As such, the quality can vary from one brand to the next, particularly those that have been imported from another country.

To ensure quality and safety, only purchase supplements from manufacturers with an established brand presence. While vitamin supplements are often voluntarily submitted for testing by an independent certifying body (like the U.S. Pharmacopeia or ConsumerLab), herbal supplements rarely are. This can leave you blind as to what is inside a supplement and what is not.

As an added layer of safety, opt for brands that have been certified organic under the regulations of the U.S. Department of Agriculture (USDA). This will reduce your risk of exposure to pesticides and other chemical toxins.

Other Questions

How do you make cat's claw tea?

The indigenous people of Peru boil traditionally boil 20 to 30 grams of the inner bark or root in a liter of water for 30 to 60 minutes.

For home use, you can steep one tablespoon (2 grams) of dried cat's claw powder in one cup of hot water for five to 10 minutes. The flavor of the tea, unsurprisingly, is bitter and woody. Some people like to mix it with rooibos tea, honey, and lemon to make it more palatable.

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