Green tea (Camellia sinensis) may have health benefits which include preventing arthritis. Study results reported in the Proceedings of the National Academy of Sciences (1999) were the first to indicate that antioxidants found in green tea, known as polyphenols, may effectively reduce the incidence and severity of rheumatoid arthritis.
Mice Fed Green Tea in Early Study
The study, led by Dr. Tariq Haqqi of Case Western Reserve University in Cleveland, Ohio, used mice to study the effect of polyphenols in rheumatoid arthritis, a rheumatic disease characterized by inflammation, pain, swelling, and joint destruction.
The mice in the study were given either plain water or water enriched with green tea. The dosages given were comparable to human consumption of four cups of green tea per day. All the mice were then injected with collagen for the purpose of inducing arthritis. Collagen-induced arthritis is considered very similar to human rheumatoid arthritis.
The study results concluded that mice which were fed the green tea polyphenols were significantly less susceptible to developing collagen-induced arthritis than the mice not fed green tea polyphenols. Of the mice fed green tea that did develop arthritis, it occurred as late onset and mild. Only 8 out of 18 mice receiving green tea polyphenols developed arthritis, while 17 out of 18 mice not receiving green tea polyphenols developed arthritis.
Examination of joint tissue microscopically revealed marginal infiltration of joint cells in mice receiving the green tea in contrast with massive infiltration in the mice not fed green tea. The effect of the green tea appeared dramatic.
In many countries such as India, China, and Japan, green tea is regarded as healthful with the potential to prevent certain illnesses.
Seemingly, rheumatoid arthritis in these countries exists at a much lower rate than elsewhere around the world and some people believe strongly in the effect of green tea.
EGCG (epigallocatechin 3-gallate) is the polyphenol in green tea which is considered to be the active ingredient. According to a report in Arthritis Research & Therapy (2010), EGCG constitutes up to 63% of total catechins.
In terms of antioxidant activity, EGCG is 25 to 100% more potent than vitamin C or vitamin E. One cup of green tea provides 60 to 125 mg catechins (including EGCG).
The Effect of EGCG on Synovial Fibroblasts
All those years ago, the potential health benefits of green tea captured the attention of researchers rather quickly. In vitro (i.e., in the laboratory) studies were conducted. In 2007, about 8 years after the first study, green tea was making headlines again. This time, researchers at the University of Michigan found that the compound in green tea might help prevent inflammation and joint damage in rheumatoid arthritis patients.
In this study, synovial fibroblasts (cells of the joint lining) were isolated and cultured. The cells were exposed to EGCG. It was determined that EGCG blocked two molecules that are associated with bone breakdown in joints affected by rheumatoid arthritis. EGCG also blocked prostaglandin E2 which is released by blood vessel walls in response to infection or inflammation. Prostaglandin E2 is associated with joint inflammation.
Clinical Trials of EGCG
The effectiveness of EGCG in human rheumatoid arthritis or osteoarthritis using phase-controlled trials has yet to be performed. While the existing in vitro studies have shown evidence of anti-rheumatic activity of EGCG, more preclinical studies are needed -- and eventually, clinical trials involving patients with joint disease.