WEDNESDAY, Nov. 16, 2005 (HealthDay News) -- Decaffeinated coffee may boost certain risk factors for cardiovascular disease.
In a study reported Wednesday at the American Heart Association's annual meeting in Dallas, decaffeinated coffee raised LDL -- or "bad" -- cholesterol, possibly by increasing levels of a blood fat called apolipoprotein B.
Experts warned that it is not yet time to substitute leaded for unleaded morning fuel, however.
"The findings are of modest changes in certain cardiovascular disease risk factors. This should not do anything to coffee-consumption patterns," said Dr. Robert Eckel, president of the American Heart Association. "An explanation is lacking. There is a need for validation and better understanding of the mechanisms at play, in that order."
The bulk of the medical literature shows that coffee, both regular and decaffeinated, generally causes no harm, Eckel added.
In this National Institutes of Health-funded study, 187 participants were randomly chosen to drink three to six cups of regular coffee each day, the equivalent amount of decaf per day, or no coffee at all. In the United States, coffee drinkers consume an average of 3.1 cups of coffee a day.
Participants prepared the coffee on their own, and were told to drink only black coffee.
Levels of caffeine in the blood were measured along with blood pressure, heart rate, body mass index (BMI, a ratio of weight to height), total cholesterol, triglycerides, HDL or "good" cholesterol, insulin, glucose, non-esterified fatty acids (NEFA or fat present in the blood stream), apolipoprotein B (associated with bad cholesterol) and LDL cholesterol.
Most of these factors are indicators of metabolic syndrome, a cluster of symptoms that puts a person at higher risk for heart disease.
The authors found no significant changes in blood insulin or glucose levels or in most other factors in the three groups.
However, after three months of drinking coffee, participants in the decaf group showed an 8 percent rise in fatty acids, and an 8 percent to 10 percent increase in LDL levels. Apolipoprotein B (ApoB) is the only protein attached to LDL, and can push up the production of LDL cholesterol, the researchers said.
NEFA also increased in the decaf group (an average of 18 percent), but not in the other two groups.
HDL2, a specific type of HDL cholesterol that is associated with a lower risk of heart disease, went up about 50 percent in overweight people drinking decaf coffee. Normal-weight people in the same group saw their HDL2 levels actually drop by about 30 percent.
"It's a complex story, and coffee is very complicated," said study author Dr. H. Robert Superko, chairman of molecular, genetic and preventive cardiology at the Fuqua Heart Center and the Piedmont-Mercer Center for Health and Learning in Atlanta. "But it doesn't mean that if you are obese you should start drinking decaffeinated coffee. Don't overinterpret this."
"The message is that there's a real difference between caffeinated and decaffeinated coffee, and it's not the caffeine," he added. "The effect on lipids is something else in the species of bean."
It's also probably not the process, he said.
Because the decaffeination process can strip the coffee of ingredients that give it flavor, a more robust bean (Robusta) is normally used, Superko explained. Regular coffee is normally made from Arabica beans, which are more mellow, he said.
It may be this initial difference in beans that cause the differences upstream, when coffee reaches the bloodstream, he explained.
More information
The American Heart Association has more on metabolic syndrome.
