The study, presented at the annual meeting of the American Heart Association, showed that people who drank decaf had higher levels of a protein linked to heart disease risk compared with those who drank caffeinated coffee or no coffee.
But the differences were fairly small and there's probably no health threat from drinking a cup or two of any type of coffee a day, says researcher H. Robert Superko, MD, chairman of preventive cardiology at the Fuqua Heart Center in Atlanta.
The Coffee Debate
The research is the latest entry into a long line of scientific studies looking at whether coffee drinking can lead to heart disease, some of which suggested links and others of which concluded the brew causes no harm.
The problem with many of the previous studies, Superko tells WebMD, is that researchers asked people about their coffee habits and lifestyles and drew associations to disease risk.
His National Institutes of Health-funded study, performed while he was at Stanford University, sought to mimic a well-controlled drug trial, randomly assigning people to a specific type and amount of coffee, brewed in a standardized manner, he says.
The participants were given premeasured bags of coffee to make in their coffee machines provided by researchers. They agreed to drink it black -- no cream or sugar allowed. And they agreed to periodic blood tests so the researchers could keep track of exactly how much caffeine they drank.
The 187 volunteers were assigned to one of three groups: no coffee, three to six cups a day of caffeinated coffee, or three to six cups of decaf. Participants also kept diet journals so researchers could determine whether eating habits influenced the results.
Fatty Acids Rise in Decaf Drinkers
After three months, there were no significant changes among the three groups in levels of blood insulin, glucose, and blood pressure, which are major risk factors for heart disease.
Levels of apolipoprotein B (ApoB) were up significantly in the decaffeinated group while staying relatively unchanged in the other two groups. The amount of ApoB has been suggested in other studies to be a better predictor of cardiovascular disease risk than one's LDL "bad" cholesterol level. This follows the notion that ApoB levels reflect the amount of smaller LDL particles, which are thought to be more sinister.
There was one group for whom decaf appeared to be heart healthy: the overweight. For those who had body mass indexes (BMIs) of more than 25, drinking decaffeinated coffee boosted levels of HDL "good" cholesterol by about 50%. Among those with lower BMIs (who were not overweight), HDL dropped 30%. Elevated HDL is known to protect the heart.
"This illustrates to the public that this is not a simple story of one coffee is good, one coffee is bad," Superko says.
Robert Eckel, MD, president of the American Heart Association and a cardiologist at the University of Colorado College of Medicine in Denver, tells WebMD that he admires the researchers for putting coffee drinking to such a rigorous scientific test. But based on this one finding, "we should not change our coffee drinking habits in America," he says.
SOURCES: American Heart Association Scientific Sessions 2005, Dallas, Nov. 13-16, 2005. Robert Eckel, MD, president, American Heart Association; cardiologist, University of Colorado College of Medicine, Denver. H. Robert Superko, MD, chairman of preventive cardiology, Fuqua Heart Center, Atlanta.
By Charlene Laino, WebMD Medical News
Reviewed by Louise Chang, MD
© 2005, WebMD Inc. All rights reserved