Green tea may help prevent autoimmune diseases

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.