A closer look at cat's claw. (Herb Watch).

Within your body there is an amazing protection mechanism--a system that protects you from all kinds bacteria, viruses, and toxins. It's your immune system. Your immune system works around the clock in so many different ways. It is a very intricate and complex system for eliminating and incapacitating any foreign invader. Sometimes the immune system overreacts to a certain stimuli, and you get an allergic response.

Immune Enhancers

There are a number of herbs that contain substances that enhance the activity of the immune system. These botanical products include echinacea, garlic, astragalus, ginseng, licorice, and cat's claw.

The immune enhancement usually results from the body's increasing its production of interferon to fight a viral infection, making antibodies to immobilize a hostile antigen, or producing a greater number of lymphocytes and other white blood cells that police the highways of the body and fight invading microorganisms.

Cat's Claw

Cat's claw has become very popular in North America over the past decade. It's known for its ability to stimulate the immune system and for its anti-inflammatory properties. Cat's claw consists of the dried bark from the root or stem of Uncaria tomentosa or Uncaria guianensis (two Amazonian vines). These large twining woody vines can grow to a length of 100 feet. The bark of the vines has long fissures and is yellowish to yellow-green in color.

Cat's claw, which is also known as Una de gato, or the life-giving vine of Peru, is indigenous to the rainforest areas of South America. Commercial supplies originate from the Amazonian rain forests of Peru and Brazil. The name cat's claw refers to the small pair of woody, curved, thornlike spines that occur on the leaf stem at the leaf junction. Uncaria has a long history of use in South America as an anti-inflammatory agent, for contraceptive activity, and to treat rheumatism, tumors, and intestinal ailments.

Identity Crisis

Cat's claw should not be confused with cat's foot, the red and white flowers of Antennaria dioica, or devil's claw, Harpagophytum procumbens, a shrubby vine that grows in southwest Africa and is also used as an anti-inflammatory agent. Furthermore, there are several other plants that may be confused with cat's claw. They may be given the name cat's claw, but they are actually quite different.

Traditional and Modern Use

Cat's claw has been used in folk medicine as a tonic and for the treatment of rheumatoid arthritis, peptic ulcers, gastritis, colitis and other intestinal ailments, tumors, dysentery, and as a contraceptive. Today some have promoted it for the treatment of Crohn's disease and chronic fatigue syndrome.

Cat's claw has been used, in combination with the drug AZT, for individuals who are HIV positive. Research continues to explore the usefulness of cat's claw for viral infections such as HIV and herpes.

Active Components

The active constituents are quite variable and depend upon the time of the year when the plant is harvested. While the stem bark has some activity, the root is three to four times more active than the stem bark. Some of the known active compounds in cat's claw include alkaloids, triterpenes, phytosterols, and proanthocyanidins.

Cat's claw's immune stimulating effect is a result of its alkaloid components. The alkaloids also possess some ability to inhibit blood clots and relax the blood vessel walls. The phytosterols are reported to have anti-inflammatory activity through their effect in stimulating interleukin production. An aqueous extract of cat's claw has shown some ability to inhibit the growth of tumor cells. The proanthocyanidins and several alkaloids appear to possess the tumor-inhibiting properties.

Safety Considerations

More research is needed to validate the safety of cat's claw. However, we do know that large quantities of cat's claw can cause low blood pressure in some people. Hence, it should be used with caution if a person is already using medications for high blood pressure, as cat's claw may potentiate the effect of the medication. Cat's claw is contraindicated in pregnancy and in nursing mothers. It may also be unsafe for young children.

Dosage

A tea can be made by boiling the root bark of cat's claw in water for five to 10 minutes and then straining the water. Tablets and capsules containing cat's claw are available in many strengths, ranging from 250 milligrams up to one gram. A typical dose would be 300-milligram capsules taken three times a day. Extracts of cat's claw are often standardized to 4 percent alkaloid content for effective results.

Conclusion

Cat's claw appears to possess immune-enhancing properties without any unwanted side effects. Further research is needed to verify other potentially therapeutic properties of this herb from South America.

Remember:

Herbal products and dietary supplements can have pharmacological effects, may produce adverse reactions in some people, and could interact with over-the-counter and prescription medications you may take. Discuss with your physician your decision to use any herbal product. Anything mentioned in this article is not intended to diagnose, prescribe, or treat any ailment.

Winston J. Craig, Ph.D., R.D., is a professor of nutrition at Andrews University, Berrien Springs, Michigan.