NEW YORK, Jul 22 (Reuters Health) -- Studies in mice suggest that green tea antioxidants may have a powerful effect in reducing the incidence and severity of rheumatoid arthritis.

Polyphenols -- antioxidants found in green tea -- "possess much more potent antioxidant activity than well-known antioxidants such as vitamin C and vitamin E," explained study lead author Dr. Tariq Haqqi of Case Western Reserve University, Cleveland, Ohio.

Recent studies have indicated that green tea polyphenols reduce levels of oxidative stress within cells, lowering risks for heart disease and certain cancers.

Haqqi's team focused on the effect of these polyphenols in rheumatoid arthritis, an autoimmune disorder in which joints are gradually infiltrated by inflammatory cells. The disease is most common in middle-aged women and is characterized by painful swelling and destruction of cartilage and bone.

Mice used in the Cleveland study were fed either plain water or water enriched with green tea polyphenols, with dosages roughly equivalent to a human drinking four cups of green tea per day.

Each of the mice were then injected with collagen, rendering them vulnerable to collagen-induced arthritis -- a condition very similar to human rheumatoid arthritis.

Haqqi's team reports in the Proceedings of the National Academy of Sciences that mice fed green tea polyphenols "were significantly less susceptible to the development of collagen-induced arthritis, and if they developed arthritis, the disease was late in onset and mild in comparison to mice not given green tea polyphenols." Overall, just 8 out of 18 mice receiving polyphenols developed arthritis, compared with 17 of the 18 mice who did not receive the compounds.

Microscopic examination of joint tissues revealed "only marginal... infiltration" of autoimmune cells in the joints of mice receiving polyphenols, versus "massive" infiltration in mice on normal diets, according to the investigators.

In a related Case Western Reserve University statement, Haqqi noted that "for many generations, in some parts of the world -- including India, China and Japan -- green tea has been considered to possess health-promoting potential by preventing many illnesses." Anecdotal evidence suggests that rates of rheumatoid arthritis in these countries may be much lower than those seen elsewhere.

Haqqi says green tea has already proven effective in reducing rates of other chronic illnesses. "Perhaps now arthritis can be added to the list," he said in a statement.

SOURCE: Proceedings of the National Academy of Sciences 1999;96:4524-4529.

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