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Green tea may help protect against
autoimmune disease, Medical College of Georgia researchers
say.
Researchers studied an animal model for type I
diabetes and primary Sjogren's Syndrome, which damages the
glands that produce tears and saliva.
They found significantly less salivary gland damage in a
group treated with green tea extract, suggesting a reduction
of the Sjogren's symptom commonly referred to as dry mouth.
Dry mouth can also be caused by certain drugs, radiation and
other diseases.
Approximately 30 percent of elderly Americans suffer from
degrees of dry mouth, says Dr. Stephen Hsu, a researcher in
the MCG School of Dentistry and lead investigator on the
study. Only 5 percent of the elderly in China, where green
tea is widely consumed, suffer from the problem.
"Since it is an autoimmune disease, Sjogren's Syndrome
causes the body to attack itself and produce extra
antibodies that mistakenly target the salivary and lacrimal
glands," he says.
There is no cure or prevention for Sjogren's Syndrome.
Researchers studied the salivary glands of the
water-consuming group and a green tea extract-consuming
group to look for inflammation and the number of
lymphocytes, a type of white blood cells that gather at
sites of inflammation to fend off foreign cells.
The group treated with green tea had significantly fewer
lymphocytes, Dr. Hsu says. Their blood also showed lower
levels of autoantibodies, protein weapons produced when the
immune system attacks itself, he says.
Researchers already know that one component of green tea
– EGCG – helps suppress inflammation, according to Dr. Hsu.
"So, we suspected that green tea would suppress the
inflammatory response of this disease. Those treated with
the green tea extract beginning at three weeks, showed
significantly less damage to those glands over time."
These results, published in a recent issue of
Autoimmunity, reinforced findings of a 2005 study showing a
similar phenomenon in a Petrie dish, Dr. Hsu says.
Researchers also suspect that the EGCG in green tea can
turn on the body's defense system against TNF-alpha – a
group of proteins and molecules involved in systemic
inflammation.
TNF-alpha, which is produced by white blood cells, can
reach out to target and kill cells. "The salivary gland
cells treated with EGCG had much fewer signs of cell death
caused by TNF-alpha," Dr. Hsu says. "We don't yet know
exactly how EGCG makes that happen. That will require
further study. In some ways, this study gives us more
questions than answers."
Further study could help determine green tea's protective
role in other autoimmune diseases, including lupus,
psoriasis, scleroderma and rheumatoid arthritis, he says.
