Oolong tea: a drink to your health?
Thursday, March 24, 2005
TYLER -- Drinking tea daily may be more than a pleasant social ritual - it might provide health benefits for older people with diabetes.
Dr. David Shafer, professor of medicine at The University of Texas at Tyler, is trying to find out if drinking a particular kind of semi-fermented tea helps lower blood sugar levels. Late last year, he received a $5,000 grant from UTHSCT to investigate if oolong tea could help control diabetes in elderly people. His was one of four small grants awarded to UTHSCT scientists to research the causes and treatments of diseases that affect the aging process.
The four grants totaled $39,500, including $11,500 from the Wolf Benevolent Trust, as well as additional funds from friends of UTHSCT Harold E. and Joy Wright, and funds from the Health Center.
In a study of Taiwan residents, those who drank oolong tea daily for 30 days showed a significant drop in their blood sugar levels, said Dr. Shafer, medical director of UTHSCT’s Center for Diabetes Care. He read about the study’s results in a 2003 issue of a major U.S. diabetes journal and was intrigued.
“Twenty participants were enrolled in the study. They drank one-and-a-half quarts of oolong tea a day. The tea lowered their blood sugar as much as any medication did,” he said. However, none were obese, which could affect the study’s outcome. Obesity is one risk factor for diabetes.
Diabetes is a disease that affects how your body uses blood sugar, or glucose, your body’s main source of fuel. Normally, insulin helps glucose enter your cells, where the glucose provides energy. In diabetes, the blood sugar accumulates in your bloodstream, and eventually is secreted in your urine. It does this, because your body is not producing enough insulin or because your body’s cells aren’t responding properly to insulin.
“Chemicals called polyphenols found in oolong tea, but not in black or green tea, apparently act to lower blood sugar levels, though how these chemicals work is not understood,” Dr. Shafer said.
“All teas basically come from the same plant, Camellia sinensis. Americans drink mostly black tea, which is completely fermented. Green tea is not fermented at all. Oolong tea is partially fermented,” he said.
“Oolong tea seems to have more of these chemicals that affect blood sugar. We don’t know if they increase the insulin levels or make the cells more sensitive to insulin,” Dr. Shafer said.
“The purpose of the study is to see if oolong tea has an effect on people in this country. We hope to have 50 participants in this small, pilot study, which is just getting ready to enroll participants,” he said. Each participant will be randomly assigned to drink either one quart of oolong tea or one quart of water a day. Their blood sugar levels will be measured before the study begins and at the end of it, Dr. Shafer said.
“If it does appear to lower blood sugar, then we’ll do further studies to see how it works. It’s important to see if it affects blood sugar, because people drink a lot of tea,” he said.
If something as inexpensive as oolong tea could be shown to consistently lower blood sugar levels, it would be a great benefit to many people with diabetes, Dr. Shafer said. However, the daily use of oolong tea to reduce blood sugar levels cannot yet be recommended, he added.
“Ideally, if you could isolate the substance in tea that does affect blood sugar levels, you could extract that and possibly have a new treatment for diabetes without actually drinking a quart of tea daily. It would be another treatment option,” he said.
For information about the study or enrolling in it, call UTHSCT’s Center for Diabetes Care at (903) 877-7569.