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.”
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.”
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. Further study could help determine green
tea’s protective role in other autoimmune diseases,
including lupus, psoriasis, scleroderma and
rheumatoid arthritis, he says.
