Coffee drinking has been linked with a reduced risk of diabetes, and now Chinese researchers think they may know why.Three compounds found in coffee seem to block the toxic accumulation of a protein linked with an increased risk of type 2 diabetes.
''We found three major coffee compounds can reverse this toxic process and may explain why coffee drinking is associated with a lower risk of type 2 diabetes," says researcher Kun Huang, PhD, a professor of biological pharmacy at the Huazhong University of Science & Technology.
Previous studies have found that people who drink four or more cups of coffee a day have a 50% lower risk of getting type 2 diabetes.
The new study is published in the Journal of Agricultural and Food Chemistry.
Type 2 diabetes is the most common type. In those who have it, the body does not have enough insulin or the cells ignore the insulin. The hormone insulin, made by the pancreas, is crucial to move glucose to the cells for energy.
Other researchers have linked the ''misfolding'' of a protein called hIAPP (human islet amyloid polypeptide) with an increased risk of diabetes. HIAPP is similar to the amyloid protein implicated in Alzheimer's disease, Huang says. When these HIAPP deposits accumulate, they can lead to the death of cells in the pancreas, Huang tells WebMD.
The Chinese researchers looked at three major active compounds in coffee and their effect on stopping the toxic accumulation of the protein:Caffeine Caffeic acid or CAChlorogenic acid or CGA
"We exposed hIAPP to coffee extracts, and found caffeine, caffeic acid, and chlorogenic acid all inhibited the formation of toxic hIAPP amyloid and protected the pancreatic cells," Huang tells WebMD.
All three had an effect. However, caffeic acid was best. Caffeine was the least good of the three.
Those results suggest decaf coffee works, too, to reduce risk, Huang says. "In decaffeinated coffee, the percentage contents of caffeic acid and chlorogenic acid are even higher [than in regular coffee], whereas the level of caffeine is greatly reduced."
"We expect that decaffeinated coffee has at least equal or even higher beneficial effect compared to the regular caffeinated types," Huang says.
In patients who already have diabetes, he says, several studies suggest decaf is better for them than regular coffee.
The National Basic Research Program of China, the Natural Science Foundation of China, and other non-industry sources funded the research.