What Is It?
Cat’s Claw, also known by its Spanish name as Una de Gato is a high-climbing, woody plant that grows profusely in the upper Amazon regions of Peru, Columbia, Ecuador, and other Latin American countries. Its botanical name, Uncaria, comes from the Latin uncus, for “hook.” And it is the vine’s clawlike stems that allow it to climb trees and other vegetation up into the forest canopy. Two species of cat’s claw are harvested for medicinal purposes, Uncaria guianensis, used mainly in Europe and Uncaria tomentosa, the one most commonly imported into the United States. Among the herbal practitioners of South America, the two species are considered interchangeable.
For hundreds of years, Amazonian people have used cat’s claw for a broad range of ailments, ranging from cancer treatment, arthritis, stomach and liver disorders, skin conditions and even contraception. Traditionally, the primary medicinal form has been a decoction or crude extract prepared from the inner bark of the stem and parts of the root.
Scientific interest in cat’s claw centers on the plant’s immune-boosting and anti-inflammatory effects. Because of this, there has been speculative evidence that cat’s claw may have anti-viral and cancer-fighting potential. In recent years, researchers discovered that there are two separate types of U. Tomentosa, with important differences in their chemical properties. One contains mostly pentacylic alkaloids, the substance responsible for the most well researched effect of cat’s claw, namely immune stimulation. The other type contains tetracylic alkaloids, which affect the brain and central nervous system and actually counteract the immune stimulating effects of the pentacylic group.
Once it became known that cat’s claw had potential value in the treatment of serious conditions involving the immune system, like cancer, arthritis and even HIV infections, by 1997, it became one of the top selling herbs in the United States. Unfortunately, this enthusiasm has not been backed up by much clinical evidence. Very few well-designed clinical trials with human subjects have been done with cat’s claw, but quite a few laboratory and animal studies have been conducted. Human studies do show that both the natural and acquired immune systems are benefited by cat’s claw. These two immune systems are differentiated by when they enter the life of a human being. The ‘natural’ immune system is ‘factory installed,’ protecting us from birth and probably even before. The ‘acquired’ immune system is the virtual library of antibodies and lymphocytes that develop as we are exposed to bacteria, viruses and even vaccinations.
Other benefits of cat’s claw are mainly anecdotal. The herb may help to improve inflammatory problems such as osteoarthritis (OA) and prostatitis, immune disorders such as lupus and rheumatoid arthritis (RA). However, it has been pointed out by some herbal researchers that long-term use might over-stimulate the immune system and do more harm than good for some of these conditions.
In Germany and Austria, the standardized extract of cat’s claw is available only by physician’s prescription, and it is used almost solely to stimulate a patient’s immune system. Clinically, the herb is prescribed mainly for cancer and HIV patients. Recently, the Austrian product, known as Immodal, was licensed to the supplement manufacturer PhytoPharma of Green Bay, Wisconsin. The root bark and stem are imported from South America and manufactured according to Austrian medical standards. Because the two ‘types’ of cat’s claw can cancel each other out, the product, sold as Saventaro® is certified to contain only penacylic aklaoids and be free from the tetracyclics.
Specifically, cat’s claw may help to:
• Support cancer therapy. In Germany and Austria, standardized extracts of cat’s claw (by prescription only) are given to some cancer patients under a doctor’s care. As an immune-boosting agent, cat’s claw may strengthen people who are undergoing chemotherapy, radiation, or other treatments for cancer. It is not known whether forms other than standardized extracts would be beneficial for cancer patients.
Reduce inflammation. In several laboratory experiments, cat’s claw has been shown to demonstrate anti-inflammatory effects. There have not been enough clinical studies in the field of inflammation to solidify a therapeutic recommendation. However, according to a small four-week trial reported in the 2001 Inflammation Research journal, 30 people with OA of the knee found significant relief of knee pain associated with activity during the first week of treatment, but no relief of night-time pain or pain during rest. They were compared to a control group of 15 people who received only placebo treatment. Other conditions which may ultimately benefit by cat’s claw are allergies and asthma, Crohn’s disease, rheumatoid arthritis, bursitis and tendonitis.
· Liquid extract
Standardization: all forms should be certified to contain the pentacylic form only. The standardized extract (Saventaro) is standardized to contain a minimum of 1.3% penatcylic oxindole alkaloids (POA’s) and to be free of tetracylic oxindole alkaloids (TOA’s)
• For osteoarthritis: Take one capsule twice a day or 15-30 drops of liquid extract twice a day
• For cancer and immune system support: Take one capsule three times a day for the first ten days and one capsule daily thereafter.
Guidelines for Use
• Take cat’s claw between meals to maximize absorption
· Because of it’s historical use as a contraceptive, its use in pregnancy is not advised.
· Some, but not all, herbalists recommend against using the herb in any condition which may be adversely affected by overstimulating the immune system. These may include auto immune disorders, multiple sclerosis and organ transplantation.
Possible Side Effects
• Mild nausea may occur if you take a crude extract or use cat’s claw tea.
• No reports of toxicity when cat’s claw is taken at recommended dosages. However, high doses may cause diarrhea, bleeding gums, excessive bruising, and a drop in blood pressure.
• A common plant found in the American Southwest, acacia greggi, is also called cat’s claw, but it is highly toxic. Some unscrupulous marketers try to pass it off as the real thing, so if you choose to use cat’s claw, purchase only products that label the plant’s species as Uncaria tomentosa.
David Edelberg, MD