The study, published in the U.S. Journal of Agricultural and Food Chemistry, also linked the ingredient to an unhealthy build-up of fat in the liver, Xinhua
news agency reported.
Previous studies showed that coffee drinkers have a lower risk of obesity, high blood pressure, type 2 diabetes and other disorders collectively termed the metabolic syndrome.
Some scientists suggested the weight loss benefit of coffee is derived from a polyphenol called chlorogenic acid (CGA) in the un-roasted green coffee bean, but they did not check its effects alone on obesity and other symptoms of the metabolic syndrome.
In their study, researchers from the University of Western Australia conducted a controlled dietary intervention over 12 weeks in special laboratory mice that are stand-ins for humans in such tests.
The researchers reported that mice on a high-fat diet and mice on a high-fat diet and CGA gained the same amount of weight.
The CGA mice, however, were more likely to develop disorders that often lead to type 2 diabetes. They also accumulated fat inside the cells in their livers.
“Our study does not support the hypothesis that supplementation of CGA to a high-fat diet will protect against features of the metabolic syndrome in obese mice,” the researchers wrote.
“Further work especially on human intervention studies is required to determine if coffee polyphenols are able to protect against metabolic syndrome and type 2 diabetes in humans,” they said.