A compound found in green tea could be an effective treatment for rheumatoid arthritis, according to the results of a new study.

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EGCG - a compound found in green tea - could help treat rheumatoid arthritis, new research suggests.

In the journal Arthritis and Rheumatology, researchers from Washington State University (WSU) in Spokane reveal how the compound - called epigallocatechin-3-gallate (EGCG) - reduced ankle swelling in a mouse model of the disease.

Rheumatoid arthritis (RA) is a disease that affects the joints of the body, most commonly the joints of the hands, feet, wrists, elbows knees and ankles.

In RA, the immune system mistakingly attacks the synovial tissues surrounding the joints, causing inflammation, swelling and pain. This can cause damage to the cartilage and bone. In more severe cases, RA can lead to joint deformity.

It is estimated that around 1.5 million people in the US have RA, and the disease is almost three times as common in women than men.

Current treatments for RA include non-steroidal anti-inflammatory drugs (NSAIDS), corticosteroids and JAK inhibitors. But study leader Salah-uddin Ahmed, of the WSU College of Pharmacy, notes that some of these treatments are expensive, reduce immune system activity and can be unsuitable for long-term use.

In their study, Ahmed and colleagues suggest that the compound EGCG may be a promising alternative to current treatments for RA.

EGCG targets key signaling protein to reduce RA inflammation

EGCG is a chemical compound that belongs to a class of flavanols known as catechins. It is most abundant in green tea and the dried leaves of white tea, and the compound is known to have anti-inflammatory properties.

After giving EGCG to mouse models of RA for 10 days, the team noticed that treatment with the compound led to a significant reduction in ankle swelling.

The researchers found that EGCG reduces the activity of TAK1 - a key signaling protein through which pro-inflammatory cytokines transmit their signals to trigger the inflammation and tissue damage found in RA.

What is more, the team says that EGCG reduced inflammation in RA without interfering with other cellular functions - unlike some current medications for the disease.

According to Ahmed, their study suggests the green tea compound may be highly effective against RA. The team concludes:

"Our findings provide a rationale for targeting TAK1 for the treatment of RA with EGCG."

Other studies have hailed green tea for its potential health benefits. In 2014, for example, Medical News Today reported on a study suggesting the beverage may benefit working memory, while other research suggests green tea protects against age-related functional disability.

A more recent study, however, claimed drinking too much green tea may do more harm than good. Published in the Journal of Functional Foods, the research found excessive amounts of the beverage impaired the reproductive function of fruit flies and the development of their offspring.

Our Knowledge Center article - "Green tea: health benefits, facts and research" - looks at some of the other ways in which green tea may help or hinder our health.