With more information emerging regularly on the potential dangers of NSAID pain relievers, patients are on the lookout for alternatives that are effective but which present fewer undesirable side-effects. One such compound that may be beneficial for certain conditions is Uncaria tomentosa, better known as cat’s claw. This plant, which is indigenous to the Amazon rain forest and other tropical areas of South and Central America, goes by the Spanish name “uña de gato,” owing to a hook-like thorn that grows along the vine and resembles a cat’s claw.

Most of the cat’s claw sold in North America comes from Peru, where it dates back to the Inca civilization, in which it may have been used for contraception, inflammation, viral infections, and to stimulate the immune system. Cat’s claw preparations are made from the plant’s roots and the vine bark, which are crushed and made into tea, or standardized extracts are available in liquid and capsule forms.

It appears that cat’s claw might not be the most impressive herbal remedy on Earth. A synopsis on the toxicology of cat’s claw noted, “Although controlled clinical studies have demonstrated reduction in pain associated with cat’s claw intake in patients with various chronic inflammatory disorders, there is insufficient clinical data overall to draw a firm conclusion for its anti-inflammatory effects. An important observation was that experimental results were often dependent upon the nature of the preparation used. It appears that the presence of unknown substances has an important role in the overall effects of cat’s claw extracts is an important factor for consideration.” Interestingly, it has also been noted that the potency of cat’s claw may depend on when it is harvested.

Nevertheless, being that medicinal use of this plant has persisted for several centuries, it looks like there may be at least something to it.

In vitro studies indicate cat’s claw may stimulate the immune system, help relax smooth muscles (including the intestines), dilate blood vessels, and act as a diuretic. The latter two effects may mean cat’s claw could be beneficial for lowering blood pressure. As it contains coumarins, it may also have natural blood thinning effects. Cat’s claw is also a potent antioxidant and anti-inflammatory, and has been used to address inflammatory conditions such as arthritis, gastritis and osteoarthritis.

In a small study of four weeks’ duration in patients with osteoarthritis of the knee (n=45), supplementation with freeze-dried cat’s claw resulted in a significant reduction in pain associated with activity compared to placebo, with this benefit occurring within the first week. Unfortunately, there was no significant reduction in knee pain at rest or at night, or knee circumference. In vitro examinations showed that the reduction in pain with activity was likely due to reductions in TNF-alpha; there was little to no effect on synthesis of inflammatory prostaglandins. In murine macrophages, lipopolysaccharide-induced TNF-alpha levels increased from 3 to 97 ng/ml. Addition of 10 microg/ml of freeze-dried cat’s claw suppressed TNF-α production by 65-85%.

As an antioxidant, cat’s claw is a potent scavenger of DPPH, hydroxyl radicals, and protects against lipid peroxidation. There’s also some evidence supporting a role for cat’s claw in protecting against oral infections. A three percent concentration of cat’s claw in Müeller-Hinton agar inhibited 8% of Enterobacteriaceae isolates, 52% of Streptococcus mutans, and 96% of Staphylococcus spp. (Concentrations of cat’s claw from 0.25 - 5% did not show antifungal effects against Candida albicans.) Another study provides additional evidence that cat’s claw shows antimicrobial activity against microorganisms frequently found in infected teeth.

There isn’t a huge body of literature on the safety of cat’s claw. And due to effects on the immune system, those with autoimmune diseases, skin grafts, tuberculosis, or those receiving organ transplants should not use cat’s claw unless specifically directed by their physician. Individuals with low blood pressure or those who take anti-hypertensive medication should avoid cat’s claw. Women who are pregnant or trying to become pregnant should also avoid this compound.