FRIDAY, June 17, 2005 (HealthDay News) -- Green tea, already lauded for its cancer-fighting ability, may also protect against certain autoimmune diseases, new research suggests.
Green teas inhibit the expression of antigens made by the body, substances that can trigger an immune response, explained study author Stephen Hsu, an associate professor in the School of Dentistry at the Medical College of Georgia in Augusta. He is to report on the research Sunday at the Arthritis Foundation's Arthritis Research Conference in Atlanta.
He focused on EGCG, a substance found in green tea known to suppress inflammation, and its effect on skin and salivary gland cells. In one autoimmune disorder, Sjogren's syndrome, the salivary glands are affected, causing dry mouth. In another autoimmune disorder, lupus, the skin is affected.
Hsu's team isolated 130 autoantigens from cells and exposed them to EGCG. Autoantigens are molecules in the body with useful functions, according to Hsu, but changes in either their amount or their location can result in an unwanted immune response.
Of the 130 autoantigens "most were inhibited or without changes" when exposed to the EGCG, he said. "Among them, a group of key autoantigens were inhibited."
While the research is very preliminary, he said, eventually green tea might help protect cells from being attacked by the autoantigens. Besides applications for the dry mouth that affects those with Sjogren's, Hsu said green tea might prove useful for the skin found in lupus.
The Georgia researcher speculated that EGCG modulates the presence of the autoantigens, in addition to its ability to suppress inflammation.
According to Hsu, other research with green tea in animal models has shown it can reduce arthritis.
The new study is "a significant beginning," said Nihal Ahmad, an assistant professor of dermatology at the University of Wisconsin at Madison, who was part of a team in 1999 that showed that polyphenols (of which EGCG is one) in green tea could prevent induced arthritis in mice.
The Hsu research, he said, "appears to have great potential," though it "needs more work." However, "based on the cell culture study, we can only say that we can be hopeful."
To learn more about tea and cancer prevention, visit the National Cancer Institute.