Green tea contains a potent anti-inflammatory compound, called "epigallocatechin-3-gallate," or EGCG, that curbs production of several molecules known to contribute to inflammation and joint damage in people with rheumatoid arthritis, the study found.

EGCG also suppresses inflammatory products in the connective tissue of people with rheumatoid arthritis, reported the researchers.

Scientists isolated certain cells, called "fibroblasts," in joint tissue and then incubated them in a growth medium with the green tea compound.

They stimulated the fibroblasts with an immune system protein that plays an important role in causing the joint destruction characteristic of rheumatoid arthritis.

The researchers investigated whether the green tea compound could block the activity of two molecules that are also actively involved in eroding bones in the joints of people suffering from rheumatoid arthritis.

Prior incubation with EGCG inhibited the production of those molecules, the researchers found. In addition, it curbed production of prostaglandin E2, a hormone-like substance the contributes to joint inflammation.

EGCG -- or molecules that could be derived synthetically from the EGCG found in green tea -- may inhibit the joint destruction in rheumatoid arthritis, according to Salah-uddin Ahmed, PhD, lead researcher on the study. Ahmed is a research investigator with the Division of Rheumatology at the U-M Health System.

The research team plans to test EGCG in animal models of rheumatoid arthritis to see if it provides similar therapeutic or preventive effects. The results will form a strong foundation for future testing of green tea compound in humans with rheumatoid arthritis, Ahmed believes.