Wu-Long tea may delay onset of type 1 diabetes
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diabetes, Medical College of Georgia researchers say.
Researchers were testing EGCG, wu-long tea's predominant antioxidant, in a laboratory mouse
with type 1 diabetes and primary Sjogren's syndrome, which damages moisture-producing glands,
causing dry mouth and eyes.
"Our study focused on Sjogren's syndrome, so learning that EGCG also can prevent and delay
insulin-dependent type 1 diabetes was a big surprise," says Dr. Stephen Hsu, molecular/cell
biologist in the School of Dentistry.
They found it also worked well in their original disease focus.
In the mouse, EGCG reduced the severity and delayed onset of salivary gland damage associated
with Sjogren's syndrome, which has no known cure.
"EGCG modulates several important genes, so it suppresses the abnormality at the molecular
level in the salivary gland. It also significantly lowered the serum autoantibodies, reducing the
severity of Sjogren's syndrome-like symptoms," Dr. Hsu says. Autoantibodies are antibodies the
body makes against itself.
Both type 1 diabetes and Sjogren's syndrome are autoimmune diseases, which cause the body to
attack itself. Autoimmune disorders are the third most common group of diseases in the United
States and affect about 8 percent of the population, says Dr. Hsu. Sjogren's syndrome can occur
alone or secondary to another autoimmune disease, such as lupus, rheumatoid arthritis or type 1
The study, published in the Oct. 24 issue of Life Sciences, supports earlier research showing
EGCG's impact on helping prevent autoimmune disease.
Researchers treated a control group of mice with water and a test group with a purified form of
EGCG dissolved in the drinking water. At 16 weeks, the EGCG-fed mice were 6.1 times more likely
to be diabetes-free than the water-fed group, and 4.2 times more likely at 22 weeks.
"Previous studies used another animal model that developed type 1 diabetes only after an injected
chemical killed the insulin-producing cells. That may not accurately resemble disease
development in humans, because type 1 diabetes is a genetic disease," says Dr. Hsu, the study's
"Our study is significant because we used a mouse model with the genetic defects that cause
symptoms similar to human type 1 diabetes and Sjogren's syndrome, so the immune cells attack
the pancreas and salivary glands until they are no longer functional."
Another related finding was that even when salivary cells were under attack, they seemed to be
rapidly reproducing in the control group. The proliferation was suppressed in the EGCG-fed group.
"It's kind of counterintuitive – why would there be proliferation of the glandular cells occurring when
the present cells are not secreting saliva?" says Dr. Kevin Gillespie, first author of the study he
conducted for his master's research project at MCG.
The proliferation phenomenon also can be observed in psoriasis, an autoimmune disease
affecting the skin and joints, says Dr. Hsu. "Normal skin cells turn over every 30 days or so, but skin
cells with psoriasis turn over every two or three days." Dr. Hsu's group previously found that green
tea polyphenols, including EGCG, inhibited rapid proliferation in an animal model for human
"We never thought proliferation was going on to this extent in the salivary gland, but we now believe
it is tightly associated with Sjogren's syndrome," he says.
The next step is to observe Sjogren's syndrome in human salivary gland samples to determine
whether the study findings hold up in humans.
"If the abnormal expression of these genes is the same in humans as in the animal model, then
the second stage will be intervention and treatment with a pure form of EGCG," says Dr. Hsu.
"The benefit of using wu-long tea in preventing or slowing these autoimmune diseases is that it's
natural and not known to harm the body," says Dr. Gillespie, periodontics chief resident at Fort
Gordon's Tingay Dental Clinic. "EGCG doesn't have the negative side-effects that can be
associated with steroids or other medications that could otherwise be prescribed."