Can Coffee Really Thwart Type 2 Diabetes?
Three potentially beneficial compounds identified in lab study
By Serena Gordon
THURSDAY, Jan. 19 (HealthDay News) -- Your morning "cup of Joe" may do more than deliver the jolt you need to get going -- it may also help you stave off type 2 diabetes, a new study suggests.
But, before you pour yourself a second cup know this: The study authors said their research was done with cell cultures and there's no proof yet that coffee has any ability to keep type 2 diabetes at bay.
Past research has suggested a link between coffee and a reduced risk of type 2 diabetes, and now Chinese researchers behind the new study think they may know why that may be so. They found three major compounds in coffee that may provide potentially beneficial effects: caffeic acid, chlorogenic acid and caffeine.
"These findings suggest that the beneficial effects of coffee consumption on type 2 diabetes mellitus may be partly due to the ability of the major coffee components and metabolites to inhibit the toxic aggregation of hIAPP [human islet amyloid polypeptide]," Ling Zheng, professor of cellular biology at Wuhan University in China, and colleagues wrote.
Human islet amyloid polypeptide (hIAPP) is a substance normally found in the pancreas, according to background information in the study. Sometimes, however, abnormal protein deposits (toxic aggregation) arise from hIAPP. These abnormal deposits (amyloid fibrils) are found in people with type 2 diabetes, the study authors said.
The researchers wondered if blocking formation of these deposits could help prevent or treat type 2 diabetes, the more common form of the blood sugar disorder. The next step would be to find a substance that might prevent these deposits.
In 2009, a study published in the Archives of Internal Medicine reported that people who drank the most coffee seemed to have the lowest risk of developing type 2 diabetes. That study reported that with each cup of coffee consumed daily, the risk of type 2 diabetes dropped by 7 percent.
So, the researchers behind the new study conducted laboratory experiments to see if compounds found in coffee could inhibit the production of the abnormal protein deposits associated with hIAPP.
Caffeic acid, chlorogenic acid and caffeine -- the three most common components in coffee, the study authors said -- helped reduce the abnormal protein deposits, but caffeic acid appeared most effective.
"Our results suggest that caffeic acid had the greatest effects in the major components of coffee. The rankings for beneficial effects of coffee compounds against the toxic hIAPP aggregation are caffeic acid, chlorogenic acid and caffeine," Zheng and study co-author Kun Huang, professor of biological pharmacy at the Huazhong University of Science & Technology in Wuhan, explained in an email interview.
Because decaffeinated coffee contains even higher levels of caffeic acid and chlorogenic acid than caffeinated coffee, the beneficial effect may be even stronger for decaffeinated coffee, they added.
The investigators pointed out that this work has only been done in cells, so it's not clear if this is how coffee might help prevent diabetes in the body.
A U.S. diabetes expert was guardedly optimistic about the study's conclusions.
"Scientifically, this is a very nice paper, but it has its limitations," said Dr. Vivian Fonseca, president of medicine and science at the American Diabetes Association. "This was done in cells, not in animals or people. We also don't know if the [abnormal deposits arising from hIAPP] are the most important thing in the development of type 2 diabetes, or if it's something that develops later."
In addition, Fonseca said, the study that found a link between a reduced risk of type 2 diabetes and coffee was an epidemiological study. That means the study couldn't prove cause and effect, only that there was an association between those two factors. It could be that people who drink coffee have other habits that lower their risk of diabetes.
The bottom line, said Fonseca, is it's way too soon to make any recommendations about drinking coffee to prevent diabetes. But, he added, "if you want to prevent diabetes, there are some very straightforward things to do. You can walk for 30 minutes most days of the week, and reduce calories a little bit and reduce your weight a little."
Zheng and Huang also pointed out that their study looked strictly at coffee. "Our study does not imply that the cream and sugar served with coffee will be beneficial for type 2 diabetes," they said.
The study was funded by grants from various Chinese governmental agencies.
Results of the study were published recently in the Journal of Agricultural and Food Chemistry.
Learn more about preventing type 2 diabetes from the American Diabetes Association.SOURCES: Ling Zheng, Ph.D., professor, cellular biology, Wuhan University, Wuhan, China; Kun Huang, Ph.D., professor, biological pharmacy, Huazhong University of Science & Technology, Wuhan, and Wuhan Institute of Biotechnology, Wuhan, China; Vivian Fonseca, M.D., president, medicine and science, American Diabetes Association; Dec. 28, 2011, Journal of Agricultural and Food Chemistry Related Articles
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