Antioxidants in green tea may prevent and reduce the severity of rheumatoid arthritis, according to a study from CWRU's School of Medicine study published in the April 13 issue of the Proceedings of the National Academy of Sciences.
The study examined the effects of green tea polyphenols on collagen-induced arthritis in mice, which is similar to rheumatoid arthritis in humans. Polyphenols are chemicals that occur naturally in certain foods, including green tea, and many work as antioxidants to protect the body from oxidative stress that causes disease.
In each of three different study groups, the mice given the green tea polyphenols were significantly less likely to develop arthritis. Of the 18 mice that received the green tea, only eight (44 percent) developed arthritis. Among the 18 mice that did not receive the green tea, all but one (94 percent) developed arthritis. In addition, researchers noted that the eight arthritic mice that received the green tea polyphenols developed less severe forms of arthritis.
"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 that cause substantial mortality and morbidity in humans," said lead author Tariq M. Haqqi, associate professor of medicine at CWRU.
"Extensive laboratory research and the epidemiologic findings of the last 15 years have revealed that polyphenolic compounds present in green tea may prevent the onset and subsequent progression of a variety of illnesses. Perhaps now arthritis can be added to the list."
Tea is one of the most commonly consumed beverages in the world, second only to water. However, only 20 percent of the tea consumed worldwide is green tea. The remainder is black tea.
"Many polyphenols in green tea possess much more potent antioxidant activity than well-known antioxidants such as vitamin C and vitamin E," said Haqqi.
Although there is no epidemiologic data, anecdotal evidence indicates that people in countries where green tea is consumed are far less likely to have rheumatoid arthritis, said the study's senior author, Hasan Mukhtar, professor of dermatology.
In the United States, however, this debilitating disease has been diagnosed in more than 2 million people. Extensive research, pioneered at CWRU School of Medicine during the past decade, has shown that antioxidants present in green tea possess cancer-preventing and anti-inflammatory properties.
Rheumatoid arthritis is an inflammatory disease that causes pain, swelling, stiffness and loss of function in the joints. There is no cure for the disease. Instead, physicians control the symptoms of rheumatoid arthritis with pain relievers and anti-inflammatory medications, which in turn slow the damage to the joints.
"The study suggests a preventive approach to rheumatoid arthritis. A slight modification in your lifestyle -- adding green tea to your diet -- could reduce your risk of this disease," said Mukhtar. "The extract given to the mice was the equivalent of a human drinking four cups of green tea a day."
In three independent experiments, six mice received water with green tea polyphenols, while six others received plain drinking water. All of the mice then were injected with collagen to induce arthritis and were studied for 40 days. One group was examined for a total of 85 days to ensure that the green tea compound was not merely delaying the onset of the disease.
In the first experiment, two of the six mice given green tea polyphenols and all six of the mice given plain water developed arthritis. In the second experiment, three of six in the green tea subset and again all six in the water group had arthritis. The incidence of arthritis in the third experiment was three of six in the green tea group and five of six among the other mice.
The study also shows the mice that developed arthritis despite receiving green tea polyphenols had a less severe form of arthritis.
"This study, in the most widely used and accepted animal model system that closely mimics the human disease, clearly shows that mice given green tea polyphenols in water were significantly protected from the development of arthritis, and, if they did develop the disease, its severity was mild," Haqqi concluded.
The article is available on the journal's Web site at http://www.pnas.org/cgi/content/abstract/96/8/4524.
The Arthritis Foundation funded the research. For more information about the foundation or information about managing arthritis, call 1-800-283-7800.
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