Cat’s Claw (Uncaria tomentosa)

Origin: The bark and root of a woody vine that grows in parts of South and Central America.

Claims: Believed to have anti-inflammatory properties; may stimulate the immune system.

What we know: Cat's claw is an anti-inflammatory that inhibits tumor necrosis factor (TNF), a target of powerful RA drugs. It also contains compounds that may benefit the immune system.

Studies: In 2002, the Journal of Rheumatology published  published a randomized double-blind study of cat’s claw for the treatment of RA. Researchers found in 40 people with RA the supplement reduced joint swelling and pain by more than 50 percent compared to placebo.

Dosage: Capsules, tablets, liquid and tea bags; 250 mg to 350 mg capsule daily for immune support. Buy only products that contain uncaria tomentosa; at least a dozen unrelated plants are also called “cat’s claw.” Look for a brand that is free of tetracyclic oxindole alkaloids (TOAs).

Cat’s claw can cause headache, dizziness and vomiting, and can lower blood pressure, so don’t use if taking an anti-hypertensive medication or blood thinner. Do not use if you have tuberculosis or are taking drugs that suppress the immune system.