Decaffeinated coffee may have a harmful effect on the heart by increasing the levels of a specific cholesterol in the blood, researchers say. Their explanation is that caffeine-free coffee is often made from a type of bean with a higher fat content.
Robert Superko, at the Piedmont-Mercer Center for Health and Learning in Atlanta, Georgia, US, and colleagues looked at the effects of coffee on 187 people. The group was split into three similar-sized groups for the three-month study: one group drank three to six cups of caffeinated coffee per day; one drank three to six cups of decaffeinated coffee per day; and a control group drank no coffee. US coffee drinkers drink an average 3.1 cups of coffee per day.
The researchers analysed blood samples from the groups before and after the study to determine the levels of cholesterol and non-esterified fatty acids (NEFAs) in the blood – key indicators of heart disease risk.
To their surprise, the researchers found the decaffeinated group had experienced an 18% rise in NEFAs in the blood and an 8% rise in apolipoprotein B – a protein associated with a cholesterol linked to cardiovascular disease. This was not seen in the other two groups.
“I believe it’s not caffeinated but decaffeinated coffee that might promote heart disease risk factors,” Superko says. “The heart risk is not great – the fatty acids can be burned off easily by exercising. But someone with high-cholesterol, who drinks four or five cups of decaffeinated coffee a day, might want to think about cutting down.”
When the researchers analysed the coffees used in the study, they found that the caffeinated and decaffeinated coffees were made from a different bean. The decaffeination process extracts the compounds that give coffee flavour, so it is often made from a stronger flavoured bean, called Robusta. Caffeinated coffees are usually made from a bean called Arabica.
“The chemical composition of the two beans is very different. Robusta contains a much higher content of fats, called diptenes, which stimulate fatty acid production in the body,” Superko told New Scientist.
“The coffee industry is selling more and more decaffeinated coffee because people think it’s healthier, but if you have high cholesterol, it may not be.”
More info from New Scientist website.