Although Western researchers have studies cat's claw since the 1970s and European doctors have used it since the 1980s, popular interest in this herb has surged only recently. Studies suggest it may boost the immune system, which may benefit people with cancer.
What it is?
In the Amazon basin of South America, one of the woody tropical vines that twines up trees in the rainforest features at the base of its leaves two curved thorns that resemble the claws of a cat. The herb derived from the inner bark or roots of this plant is known as cat's claw, or una de gato (its Spanish common name). although there are dozens of related species, two specific ones, Uncaria tomentosa and U. guianensis, are harvested in the wild (primarily in Peru and Brazil) for medicinal purposes. Large pieces of their bark are a common sight in South American farmers' markets; the indigenous peoples have long made tea from the bark and used it to treat wounds, stomach ills, arthritis, cancer and other ailments.
What it does?
Modern scientific studies have identified several active ingredients in cat's claw that enhance the activity of the immune system and inhibit inflammation. Their presence may help to explain why this herb traditionally has been employed to fight cancer, arthritis, dysentery, ulcers, and other infectious and inflammatory conditions.
In Germany and Austria, doctors prescribe cat's claw to stimulate the immune response in cancer patients, many of whom may have been weakened by chemotherapy, radiation or other conventional cancer treatments. Several compounds in the herb – some of which have been studied for decades – may account for its cancer-fighting and immune-boosting effects. In the 1970s, researchers reported that the inner bark and root contain compounds called procyanidolic oligomer (PCOs), which inhibit tumours in animals. In the 1980s, German scientists identified other compounds in cat's claw that enhance the immune system, in part by stimulating immune cells called phagocytes that engulf and devour viruses, bacteria and other disease-causing micro-organisms. Then, in 1993, an Italian study detected another class of compounds, called quinovic acid glycosides, that have multiple benefits. These act as antioxidants, ridding the body of cell-damaging molecules called free radicals. They also kill viruses, reduce inflammation, and inhibit the transformation of normal cells into cancerous ones.
In addition to its anti-tumour potential, cat's claw may be of value in combating stubborn infections such as sinusitis.
Traditionally, the herb has been relied on to treat pain. Because of its anti-inflammatory properties, it may be effective in relieving joint pain caused by arthritis or gout. Additional studies are needed, however, to define the precise role that cat's claw plays in treating arthritis and other inflammatory complaints.
Some preliminary reports found that cat's claw, in conjunction with conventional AIDS drugs, may benefit people infected with HIV because it seems to boost the immune response, but further studies are necessary. Some experts caution against taking the herb for chronic conditions affecting the immune system, including tuberculosis, multiple sclerosis and rheumatoid arthritis, because they believe it may over-stimulate the immune system and make symptoms worse. Other doctors, however, recommend it for auto-immune disorders, including rheumatoid arthritis and lupus. More research must be undertaken.
- May enhance immunity, making it useful for sinusitis and other infections.
- Enhances cancer treatment.
- May help to relieve chronic pain.
- Reduces pain and inflammation from gout or arthritis.
- Soft gel.
- Dried herb/tea.
Never take cat's claw if you are pregnant or considering pregnancy, or are breast-feeding. Its safety is not established in these situations, and it may bring on a spontaneous miscarriage.
Reminder: If you have a medical condition, talk to your doctor before taking supplements.
How to take it?
Take 250 mg of a standardized extract in pill form twice a day. Alternatively, take 1-2 ml (20-40 drops) of the tincture twice a day. Pills containing the crude herb (the ground root or inner bark in a non-concentrated form) may be available in 500 mg or 1000 mg capsules. Have these twice daily (up to 2000 mg a day). Cat's claw tea is sold in health-food shops; use 1 or 2 teaspoons of dried herb per cup of very hot water. (Follow packet directions). You can drink up to three cups a day.
Guidelines for use:
You can combine or rotate cat's claw with other immune-stimulating herbs, such as echinacea, goldenseal, reishi and maitake mushrooms, astragalus or pau d'arco.
Pregnant or breast-feeding women should avoid cat's claw. In Peru, cat's claw has long been valued as a contraceptive. In animals, it stimulates uterine contractions, and this suggests that the herb could induce a miscarriage in humans.
Possible side effects
Although there have been few studies on the safety of this plant, there have been no reports that it is toxic at recommended doses. Taking higher doses, however, may cause diarrhoea.
Facts and Tips
Even though cat's claw root may contain higher percentages of active ingredients than its inner bark, the latter is preferred for ecological reasons. When the inner bark is harvested, it is possible to keep the tree alive, whereas uprooting the plant will kill it. If you buy a standardized extract made from inner bark, you'll get a guaranteed level of active ingredients.
- Whenever possible, select standardized extracts of cat's claw to help ensure that you're getting a proper dose of the herb. Look for preparations standardized to contain 3% alkaloids and 15% polyphenols.
- Buy supplements made from Uncaria tomentosa or U. guianensis. Many products on the market do not include actual cat's claw, but rather herbs that look like the real thing or carry the same name. These include preparations from the south-western United States containing a completely unrelated plant (Acacia greggii) that's also called cat's claw. Check the ingredients on the label carefully, and buy cat's claw from a reputable supplier.
Did you know?
In Germany and Austria, cat's claw extract is considered a potent medicine, and is typically dispensed only with a doctor's prescription.