Why cat’s claw is so intriguing

Approximately 68 percent of American adults take dietary supplements, according to a 2015 survey conducted by the Council for Responsible Nutrition (CRN).

One of the most popular supplements is cat’s claw, which was ranked seventh in U.S. sales in 1997.

The name derives from its appearance – cat’s claw has “hook-like horns.” This woody vine can be found in the Amazon rainforest as well as in other locations in South and Central America and has been used for centuries for a number of health issues, from arthritis and inflammation to dysentery and fevers.

Benefits of cat’s claw

According to Raintree, a tropical plant database, both the bark and roots of cat’s claw can be used in a variety of ways. In addition to the above-mentioned uses, cat’s claw is said to kill viruses, cleanse the blood, detoxify, lower blood pressure and cholesterol, increase urination, and reduce depressive symptoms, the site notes.

Studies on the effectiveness of cat’s claw began in the 1970s in Austria, according to Raintree. For instance, a 2001 study reported that cat’s claw helped decrease pain in adult patients with osteoarthritis. Within the first week of therapy with Uncaria guianensis, a species of cat’s claw, subjects said they had reduced pain with activity. Medical assessment showed some improvement in pain status.

Research results

Uncaria tomentosa, another species of cat’s claw, was used in a 2002 study on potential benefits for rheumatoid arthritis. During this 52-week, two-phase study, some subjects received the plant extract during the first phase and other subjects received placebo.

At week 24, all subjects in the study group reported a decrease in the number of painful joints when compared to those in the control (placebo) group. All subjects received the plant extract in the second phase. The authors note that the results show that cat’s claw is safe and holds some benefits for individuals with rheumatoid arthritis.

Another study showed that both species of cat’s claw have antioxidant and anti-inflammatory properties, although Uncaria guianensis may be more potent.

Josh Axe, DNM, DC, CNS, reports that cat’s claw comes in six different forms: liquid extract, capsule, tablet, tea, cream and tincture and can be found in health food stores or online. Dosage recommendations vary, depending on the form. The suggested dose for one form of cat’s claw bark is 300 milligrams daily, although Axe emphasizes users should follow label instructions or consult an expert. Cat’s claw cream can be applied to the skin for relief of arthritis, rheumatism, and other muscle and joint problems.

Words of caution

WebMD indicates that cat’s claw is possibly safe “when taken by mouth short term.” But in some cases, it can cause headaches, dizziness, and vomiting. The supplement is deemed possibly unsafe in pregnant and nursing women. Cat’s claw may also activate the immune system in individuals with autoimmune disorders, such as lupus and multiple sclerosis, so individuals should consult their physician before using the supplement.

Cat’s claw might also impede blood clotting and lower blood pressure, according to the site. Because of this, Cat’s claw is not recommended for use immediately before or after surgery.

In spite of some favorable study data, Stuart Spitalnic, MD, clinical assistant professor of Emergency Medicine, Brown University, Alpert Medical School,  urges caution when interpreting findings. “Studies of ‘inflammation’ and biomarkers are completely worthless as the medical literature is littered with discarded therapies that have good theoretical basis and excellent surrogate marker profiles, but either don’t work or are harmful when used clinically. This applies to traditional medicine as well,” he says.

Spitalnic points out that these studies are small, difficult to validate and present positive results, but downplay others that were not.  “These other findings, if there were a real mechanism involved, should also have had some effect,” he says.

The bigger issues with very small studies of questionable practices come under “circular file bias” and “publication bias,” according to Spitalnic. “If you do a small study of a ‘nonsense’ therapy and it doesn’t work, you are not going to submit it for publication, and if you do, it is not going to get published.  Further, it is very unclear from the studies what exactly were the primary endpoints. Were they well defined or did they collect a lot of data and point to the results that were positive by random chance and say, ‘See, we found something’,” he says.

Spitalnic asserts that the only proper conclusion from small studies “… is to say that you may have found smoke, and now it is time to check for fire.” He adds, “What should happen, based on the data from small studies, is a large, properly designed study should be undertaken with pre-defined endpoints. Without a good, big study you can’t be 100 percent sure that it will fail, but odds are it will. More than nine times out of ten, these studies find no effect of treatment, and having looked at dozens of these types of treatments, there is no reason to suspect that cat’s claw will be any different.”