In a major turnaround, researchers now believe that decaffeinated - not caffeinated - coffee may cause an increase in LDL (bad) cholesterol by increasing a specific type of blood fat linked to the metabolic syndrome. "These results are very surprising and have never been reported before for coffee consumption. This is the first non-industry-sponsored study of its kind... looking at the mechanism of how a particular kind of coffee consumption increases LDL cholesterol," said researcher H. Robert Superko. The study was presented at the American Heart Association's Scientific Sessions conference.
Superko said the new study addressed several of the shortcomings of previous studies. "The problem with the results from these previous studies is that many of them were association studies, which looked broadly at free-living populations and drew associations between lifestyle factors, volitional coffee consumption, and disease risk. Our study randomized subjects to a specific type and amount of coffee consumption, brewed in a standardized manner, just like a drug study," he explained.
Participants in the new study were randomized into three groups: one that drank three to six cups of caffeinated coffee a day; another that drank three to six cups of decaffeinated coffee a day; and a third, the control group, that drank no coffee. All the study's participants drank only black coffee.
The researchers then looked at key indicators of the metabolic syndrome in the participants. Metabolic syndrome is the umbrella term for a cluster of several harmful heart disease risk factors, including blood pressure, heart rate, BMI, total cholesterol, triglycerides, HDL (good) cholesterol, levels of insulin, glucose, and apolipoprotein B (ApoB - a protein associated with LDL (bad) cholesterol).
The study found no significant changes among the three groups' levels of blood insulin and glucose, or other major risk factors. But they reported for the first time that, after three months of coffee drinking, the decaffeinated group experienced a rise in fatty acids, the fuel in the blood that can drive the production of LDL cholesterol. ApoB - which researchers believe might be a better predictor of cardiovascular disease risk than LDL level - went up 8 percent in the decaffeinated group but did not significantly change in the other two groups.
Superko explained that the absence of caffeine was not the only difference between the two types of coffee. "Caffeinated and decaffeinated coffees are often made from different species of beans. Caffeinated coffee, by and large, comes from a bean species called coffee Arabica, while many decaffeinated coffees are made from coffee Robusta. The decaffeination process can extract flavonoids and ingredients that give coffee flavor. So, decaffeinated brands usually use a bean that has a more robust flavor."
"I believe it's not caffeinated but decaffeinated coffee that might promote heart disease risk factors that are associated with the metabolic syndrome," said Superko. He added that people concerned about increasing fatty acids and LDL cholesterol should think twice about drinking a lot of decaffeinated coffee.
Source: American Heart Association