Curcuma longa, Cur­cuma domestica

Origin: A yellow-colored powder ground from the root of the turmeric plant. The turmeric plant grows in India and Indonesia and is related to the ginger family (it is a common ingredient in curries). Curcumin is a key chemical in turmeric.

Claims: Reduces pain, inflammation and stiffness related to rheumatoid arthritis (RA) and osteoarthritis (OA); treats bursitis. Known as a cleansing agent, turmeric often is used as a digestive aid in India.

What we know: Traditionally used in Chinese and Indian Ayurvedic medicine to treat arthritis turmeric/curcumin blocks inflammatory cytokines and enzymes, including cyclooxygenase-2 (COX-2), the target of celecoxib (Celebrex).

Studies: Several recent studies show that turmeric/curcumin has anti-inflammatory properties and modifies immune system responses. A 2006 study showed turmeric was more effective at preventing joint inflammation than reducing joint inflammation.

A 2010 clinical trial found that a turmeric supplement called Meriva (standardized to 75 percent curcumin combined with phosphatidylcholine) provided long-term improvement in pain and function in 100 patients with knee OA.

In a small 2012 pilot study, a curcumin product called BCM-95 reduced joint pain and swelling in patients with active RA better than diclofenac, an nonsteroidal anti-inflammatory drug (NSAID).

Dosage: Capsules, extract (more likely to be free of contaminants) or spice. For OA: Capsule, typically 400 mg to 600 mg, three times per day; or 0.5 g to 1 g of powdered root up to 3 g per day. For RA: 500 mg twice daily.

"Curcumin makes up only about 2 to 6 percent of turmeric, so be sure to check the standardized amount of curcumin," advises Randy Horowitz, MD, medical director of the University of Arizona Center for Integrative Medicine in Tucson.

High doses of turmeric can act as a blood thinner and cause stomach upset. Avoid turmeric/curcumin if you take blood thinners such as warfarin (Coumadin), are about to have surgery, are pregnant or have gallbladder disease.