Though several studies have shown that coffee may actually be good for you, new research shows that too much java may be bad for some coffee lovers' hearts.
For a nation fueled by Starbucks, studies suggesting that coffee drinkers may be at decreased risk for several major diseases, including Parkinson's and diabetes, is welcome news.
WebMD even recently reported on two studies from The Journal of the National Cancer Institute showing that coffee may significantly lower the risk of colon and liver cancers.
But there is also evidence that coffee may increase the risk of heart disease for some, and a new study from Greece seems to bolster the claim.
Researchers from the University of Athens found that coffee drinkers had more stiffness of the major blood vessel of the body than non-coffee drinkers. Decreased elasticity of major blood vessels is a risk factor for developing heart disease like heart attack and stroke.
The findings are reported in the June 1 issue of the American Journal of Clinical Nutrition.
The researchers had already linked coffee drinking to increased indicators of inflammation, one of the key mechanisms to the development of heart disease. And they have also reported that combining coffee with cigarette smoking seems to be much worse for the heart than smoking alone.
"The evidence regarding coffee is far less conclusive than it is for smoking," study researcher Charalambos Vlachopoulos, MD, tells WebMD. "But it still might be prudent for people who drink more than three cups of coffee a day to cut down, especiallyif they have high blood pressure or other risk factors for heart disease."
Read WebMD's "Caffeine Tied to Blood Sugar Problems"
The Research
Previous studies evaluating coffee's role in promoting high blood pressure and heart disease have been conflicting. Though some suggest a strong link, others have found no link at all or even a health benefit to coffee drinking.
The latest research by Vlachopoulos and colleagues included 228 healthy adults whose average age was 41. The researchers used food-frequency questionnaires to determine how much coffee each study participant drank. They took into account whether participants drank instant coffee, brewed coffee, Greek-type coffee, cappuccino, or filtered coffee. They analyzed the data to account for each cup of coffee containing 80 milligrams of caffeine.
They also measured blood vessel wall abnormalities -- wall stiffness, the inability to expand and contract and a sign of unhealthy blood vessels.
Compared with people who did not drink coffee, people who drank two or more cups of coffee a day showed more abnormalities in blood vessel function. Blood vessel stiffness is an indictor of heart disease risk. The association remained strong even after taking into account other heart disease risk factors like smoking, obesity, and age.
But nutrition researcher Alice Lichtenstein, DSc, says the lifestyle differences between the coffee drinkers and non-coffee drinkers were so great that it would be difficult for the researchers to take these into account.
Lichtenstein is a senior scientist and director of the Cardiovascular Nutrition Laboratory at Boston's Tufts University. She is also a spokeswoman for the American Heart Association.
In the study, people who drank two or more cups of coffee a day were almost nine times more likely than non-coffee drinkers to smoke cigarettes. They were also 2.5 times as likely to be obese. In general, people who drank no coffee also tended to be younger than those who drank coffee.
Age, cigarette smoking and obesity are three risk factors for heart disease. "It is more likely that heart disease risk is determined by a number of dietary and lifestyle components together, rather than individual foods," she tells WebMD.
Read WebMD's "Do You Know the Right Way to Drink Coffee?"
Moderation Is Key
Lichtenstein agrees that as a whole, the research on coffee and health remains inconclusive. She adds that java junkies can probably relax if they drink coffee in moderation and reserve the cream and sugar-laden specialty coffees for special occasions.
While coffee itself has no calories, the "tall" version of, say, a double-mocha latte with whipped cream can contain more calories, fat, and sugar than a typical fast-food meal.
Vlachopoulos says it is increasingly clear that coffee consumption is an important risk factor for heart disease when combined with smoking.
"The message to smokers would be to stop, and if they can't stop they shouldn't drink coffee," he says.
By Salynn Boyles, reviewed by Brunilda Nazario, MD
SOURCES: Charalambos, V. American Journal of Clinical Nutrition, June 2005; vol 81: pp 1307-1312. Charalambos Vlachopoulos, MD, department of cardiology, Hippokration Hospital, School of Medicine, University of Athens, Greece. Alice Lichtenstein, DSc, senior scientist, director, Cardiovascular Nutrition Laboratory, Tufts University, Boston; spokeswoman, American Heart Association.
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