coffee: there’s still a latte we don’t know

Coffee is one of the most frequently consumed — and well studied — beverages in the world. But researchers continue to debate its potential dangers and benefits, particularly for those at risk for age-related problems, such as heart disease and osteoporosis.

Around the globe, millions of bleary-eyed people depend on a steaming cup of hot coffee to get them going in the morning. What they might not realize is that their daily dose of java could be doing a lot more than boosting their alertness. Researchers are finding that coffee has a multitude of effects on the body — some good, some bad.

In a study published in the October issue of the American Journal of Clinical Nutrition, researchers at Harokopio University and the University of Athens in Greece reported that people who drank more than one cup of coffee a day had higher concentrations of inflammatory molecules, such as C-reactive protein and interleukin-6, than did those who did not imbibe the beverage. Inflammation, the body’s response to injury, is thought to promote aging-related illnesses, including heart disease, as well as other health problems. Study co-author Demosthenes Panagiotakos speculates that the culprits might be cafestol and kahweol — substances found in unfiltered coffee (which few Americans drink) that have been linked to high cholesterol quantities.

But other studies on coffee consumption and cardiovascular health have produced contradictory results. Meir Stampfer, an epidemiologist at the Harvard School of Public Health in Boston, who has been studying coffee and health for decades, does not regard coffee as a hazard to the heart; people who drink a lot of coffee tend to engage in other behaviors — cigarette smoking, for example — that could damage their hearts. Stampfer controls for these confounding factors when analyzing his own study results. “Unless you carefully adjust for smoking and other behaviors, coffee can look worse for you than it really is,” he says.

Although Panagiotakos and his colleagues accounted for smoking as well as other factors that could have influenced their conclusions, the study might have limitations, says Jack Guralnik, an epidemiologist at the National Institute on Aging (NIA) in Bethesda, Maryland. For example, the investigators had to rely on self-reports of coffee consumption, which could lead to possible errors. Also, because the researchers measured the inflammatory markers and the volume of coffee consumption at the same time, they are unable to draw any conclusions about cause and effect: “You can never really tell what came first,” Guralnik says. “Is it that people with inflammation have something going on that makes them drink more coffee?”

Furthermore, the Greek study does not examine heart disease directly, notes Stampfer. The researchers found increased amounts of certain inflammatory markers, he says, but “it’s quite a couple of big leaps to infer from this that coffee would cause heart disease. If it were the only information we had about coffee and health, I’d say this is a concern, and we should see if people who drink coffee have more heart disease.” But because Stampfer’s studies have failed to find a link between coffee drinking and cardiovascular disease, “I’ve sort of crossed that off the list of things to worry about.”

Guralnik, on the other hand, says the Greek study raises an interesting finding and warrants further investigation. Based on the potential link between coffee and inflammation, Guralnik says he feels comfortable advising that large amounts of the beverage be avoided. Because inflammation might play a role in heart disease as well as some other aging-related problems, such as declining muscle strength, he says, “anything that increases inflammation is probably not good for older people.”

Whether or not coffee induces inflammation, its caffeine can trigger arrhythmia in people with an irregular heartbeat or heart problems, so certain categories of patients should avoid consuming the stimulant, says Tomas de Paulis, a research scientist at the Institute for Coffee Studies at Vanderbilt University in Nashville, Tennessee, which is funded by various coffee associations.

And Linda Van Horn, a member of the Nutrition Committee of the American Heart Association, advises that older adults should be “prudent about their intake of probably everything” due to age-related changes in their bodies. Because seniors don’t sense thirst as well as younger people do, she cautions older adults to be aware of coffee’s diuretic effects to avoid becoming dehydrated.

Although Stampfer is dubious about links between coffee consumption and heart disease, he and his colleagues have found that coffee drinking slightly increases the risk of developing osteoporosis because the beverage can increase calcium excretion. In addition, other researchers reported in the November 2001 American Journal of Clinical Nutrition that caffeine can increase bone loss in elderly women, but only if the women had a specific form of a gene that made them susceptible to its effects.

But not all the news on coffee is bad. On the plus side, de Paulis mentions that coffee is unusually high in antioxidants, which some experts believe could exert antiaging effects. He adds that the beverage has protected people against cirrhosis of the liver, particularly in those who drink and smoke. And Stampfer and his colleagues, using data from large prospective studies, such as the Nurses’ Health Study, have found that coffee drinking might lead to lower risks of diabetes, Parkinson’s disease, gallstones, and kidney stones.

Although Stampfer says that overdoing coffee is possible, the typical couple of cups that many people drink per day do not pose serious hazards as long as they’re getting enough calcium to counteract the small risk of osteoporosis he’s seen in coffee drinkers. “I wouldn’t drink it for health, I don’t regard it as a medicine,” he says. “But for people who like coffee, there’s no clear reason to avoid it for health concerns.” The American Heart Association and the American Dietetic Association agree that drinking coffee in moderation appears to be safe. De Paulis adds no strong evidence indicates that coffee might be any worse for older adults than for their younger peers.

The debate over coffee’s drawbacks and benefits probably won’t be settled anytime soon, a situation that should come as little surprise given that the brew’s reputation has been fluctuating for hundreds of years. Voltaire, when told by his doctor that coffee was a slow poison, reportedly replied, “It must be. I’ve been drinking it for more than 60 years, and I’m not dead yet.

This article appeared in the the “Latest News and Views” section of Sage Crossroads’ online forum on November 29, 2004.
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