MONDAY, Dec. 14, 2009 (HealthDay News) -- Here's good news for people who can't start their morning without a cup or two of java: Coffee and tea consumption may decrease the risk of developing type 2 diabetes.
That's the conclusion of an Australian study that also found the more coffee you drink, the lower your risk of diabetes. Every cup of coffee was associated with a 7 percent reduction in the risk of diabetes, the researchers said.
"There is good evidence that consumption of coffee, including decaffeinated coffee, and tea is independently associated with a reduced risk of developing type 2 diabetes," said the study's lead author, Rachel Huxley, an associate professor and director of the renal and metabolic division at The George Institute for International Health at the University of Sydney in Australia.
Results of the study are published in the Dec. 14/28 issue of the Archives of Internal Medicine.
Other studies have also noted health benefits from coffee. Last week, at the American Association for Cancer Research meeting, researchers reported that coffee consumption reduced the risk of dying from prostate cancer. According to other studies, coffee may help thwart liver disease, Alzheimer's, stroke and Parkinson's disease.
Experts initially thought caffeine was the source of any health advantages from coffee. However, research on decaffeinated coffee suggests that java minus the caffeine can still benefit your health.
In an attempt to better assess the relationship between coffee, decaffeinated coffee and tea on diabetes risk, Huxley and her colleagues reviewed 18 previously completed studies that included 457,922 people. Six of those studies included information on decaffeinated coffee consumption, while seven included information on tea-drinking habits.
The researchers found that people who drink three to four cups of coffee daily had about a 25 percent reduction in their risk of developing type 2 diabetes compared to those who drank no coffee or up to two cups a day. For every cup of coffee consumed each day, the risk of developing diabetes dropped by about 7 percent, the study found.
Results for decaffeinated coffee and tea were also positive. Those drinking three to four cups of decaffeinated coffee per day lowered their risk of diabetes by about one-third compared to those who had no coffee each day. Those drinking three to four cups of tea each day lowered their risk of diabetes by about one-fifth compared to those who didn't drink tea, according to the study.
The researchers weren't able to assess a per cup risk reduction for tea or decaffeinated coffee, as they did for regular coffee, because there wasn't enough data in the published studies to do so, Huxley said.
It was previously believed that caffeine provided most of coffee's beneficial effects, but now experts suspect that "other components of these beverages, such as magnesium, lignans and chlorogenic acids, may also have a role," Huxley said.
She said those components appear to have a beneficial effect on blood sugar regulation and insulin secretion, but that further research is necessary.
"This study adds to the body of evidence that our diet and lifestyle are important determinants of subsequent diabetes risk," said Huxley. "Although it is too early to advocate for increased consumption of tea and coffee as a way of preventing diabetes, if these findings are confirmed by clinical trials, then the identification of the protective components in these beverages would open up new therapeutic pathways for the primary prevention of type 2 diabetes."
Other experts agree more research is needed.
"Coffee or tea may have an effect on diabetes risk, but in order to prove it, you need prospective studies," said Dr. Joel Zonszein, a professor of medicine and director of the clinical diabetes center at Montefiore Medical Center in New York City.
With regard to preventing diabetes, he said, "Coffee doesn't hurt, but you have to watch your diet and get enough physical activity."
Learn more about eating right to help prevent diabetes and other illnesses from the U.S. Centers for Disease Control and Prevention.