MONDAY, April 24, 2006 (HealthDay News) -- If you're reading this over your morning cup of coffee, you can sip away with the comforting thought that a new study found no relationship between drinking lots of the brew and coronary heart disease.
Data on more than 120,000 participants in two U.S. studies that followed people for as long as two decades found no link between heart disease and a daily intake of six or more cups of coffee. In fact, the risk was the same as for people who had less than one cup of coffee or tea a month.
A couple of caveats go with the overall findings, the researchers said.
"We can't exclude the association between coffee consumption and the risk of coronary heart disease in small groups of people," said Rob van Dam, a research scientist at the Harvard School of Public Health, and a co-author of the report.
For instance, a recent study suggested that one form of a gene responsible for metabolism of caffeine could make coffee harmful to people who carry the gene, van Dam said, "although that finding requires confirmation."
And the new findings don't apply to heavy consumption of unfiltered coffee, such as the French press kind, he said. "Studies have consistently shown that drinking a lot of French press coffee increases low-density lipoprotein, the bad cholesterol," van Dam said.
The new findings appear in the April 25 issue of the journal Circulation.
What you put into your coffee cup other than coffee also matters, said Alice Lichtenstein, professor of nutritional science and policy at Tufts University, and chairwoman of the American Heart Association's nutrition committee.
"Just because there is no association between coffee and cardiovascular disease, that doesn't give free rein to order whatever you want at a coffee shop," she said. "The saturated fat in cream or whole milk and the sugar that is put in warrant consideration. Having black coffee or no-fat milk is one thing. It's another thing to drink coffee with lots of calories in it."
The researchers behind the new study had to adjust their risk estimates for other habits that often go with coffee consumption. For example, heavy coffee drinkers were more likely to drink alcohol and use aspirin, and less likely to exercise and use vitamin supplements. And there was a strong association between coffee consumption and smoking; more than half the women and 30 percent of the men drinking six or more cups a day also smoked cigarettes.
Some other findings in the study:
- There was no difference in heart risk between women who frequently drank decaffeinated coffee and those who did not.
- There was no significant difference in blood levels of total cholesterol, HDL ("good") cholesterol and LDL ("bad") cholesterol in coffee drinkers, whether they favored caffeinated or decaffeinated coffee.
- Type 2 diabetes, the kind that generally develops later in life, had no effect on heart-disease risk -- or the lack of risk -- associated with drinking coffee.
Van Dam had some advice for coffee drinkers. "If you perceive unpleasant symptoms, such as difficulty falling to sleep when consuming caffeinated coffee, that means you drink too much," he said.
And women who are pregnant or nursing should limit themselves to three or fewer 8-ounce cups a day because "the child is very sensitive to caffeine," he said.
Also, "persons with specific diseases such as heart conditions can consult their physicians about prudent coffee consumption," van Dam said.
For more on caffeine and the heart, visit the American Heart Association.