DALLAS, Nov. 16 \ufffd Decaffeinated \ufffd not caffeinated \ufffd coffee may cause an increase in harmful LDL cholesterol by increasing a specific type of blood fat linked to the metabolic syndrome, hints a new study presented at the American Heart Association\ufffds Scientific Sessions 2005.

The Coffee and Lipoprotein Metabolism (CALM) study included 187 people, randomized to 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.

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Researchers measured the level of caffeine in the blood of the participants, as well as levels of the key heart-health indicators before and after the three-month study.

They sought to clearly demonstrate the effects of caffeinated and decaffeinated coffee consumption on key indicators of the metabolic syndrome, which is the umbrella term for a cluster of several harmful heart disease risk factors. Researchers looked at blood pressure, heart rate, BMI, total cholesterol, triglycerides, HDL (good cholesterol) levels of insulin, glucose, non-esterified fatty acids (NEFA \ufffd fat in the blood), apolipoprotein B (ApoB \ufffd a protein associated with LDL or \ufffdbad\ufffd cholesterol) and high-density lipoprotein 2 (HDL2 \ufffd a type of \ufffdreally good\ufffd cholesterol).

Researchers found no significant changes among the three groups\ufffd 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, which is the fuel in the blood that can drive the production of low-density lipoprotein LDL.

ApoB went up 8 percent in the decaffeinated group but did not significantly change in the other two groups. ApoB is the only protein attached to LDL, and studies show that ApoB might be a better predictor of cardiovascular disease risk than one\ufffds LDL level.

NEFA rose an average 18 percent in the decaffeinated group, while it did not change in the other two groups.

\ufffdNEFA is the fuel that can drive the increase in ApoB and LDL,\ufffd Superko said. \ufffdThese results are very surprising and have never been reported before for coffee consumption. This is the first non-industry-sponsored study of its kind. Until now, researchers had not reported on a randomized prospective study looking at the mechanism of how a particular kind of coffee consumption increases ApoB and LDL-cholesterol.

\ufffdThere is a real difference between caffeinated and decaffeinated coffee and, contrary to what people have thought for many years, I believe it\ufffds not caffeinated but decaffeinated coffee that might promote heart disease risk factors that are associated with the metabolic syndrome, an expanding heart-health hazard in the United States.\ufffd

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The National Institutes of Health (NIH) funded the study.