It's believed to improve mood, alertness, and energy. But is coffee bad for you? Despite past concerns about coffee, tea, and other sources of caffeine being detrimental to health, recent research suggests that regular coffee consumption may reduce the risk of health conditions such as type 2 diabetes, Parkinson's disease, and liver cancer—and regular coffee drinkers might even live longer. "For most people [who] choose to drink coffee, the benefits probably outweigh the risks," says Donald Hensrud, chair of the division of preventive medicine at the Mayo Clinic in Rochester, Minn.
"In the past, a lot of people have tried to improve their health by cutting down on coffee," says Rob M. van Dam, assistant professor of nutrition and epidemiology at the Harvard School of Public Health. But that's probably an unnecessary sacrifice. Although experts once thought caffeine was harmful, recent "studies have been largely reassuring," he says. In the past, it has been hard to differentiate the health effects of coffee versus those tied to smoking cigarettes, since heavy coffee drinkers are more likely to smoke than other people.
Coffee is "not only a vehicle for caffeine," says van Dam. "It has a lot of other components." It's likely that those other components—such as antioxidants and fiber—account for some of coffee's health benefits, experts say. "We always hear about tea, and especially green tea, being a good source of antioxidants, but it's been reported that coffee may be the largest source of antioxidants among people who drink it," says Hensrud. More research is needed to understand how these other ingredients might benefit health among coffee drinkers.
Pregnancy problems. Experts say that caffeine should be avoided or limited during pregnancy. Drinking coffee during pregnancy has been linked to lower birth weight and an increased risk of miscarriage and stillbirth, though there is no proof at this point that caffeine causes miscarriages, according to the American College of Obstetricians and Gynecologists. "We don't really know what the health effects of caffeine are for the fetus," van Dam says.
For those loyal to coffee, even quitting for the sake of their babies can be difficult. Zena Elizalde, 28, of Owings Mills, Md., said she struggled with giving up caffeine when she was pregnant, but she did cut back to one cup per day, half caffeinated, half decaffeinated. Since delivering a healthy baby in January, Elizalde is back up to her usual three-cups-per-day routine. She has her first cup at 8 or 9 a.m., another at 2 p.m., and a third at 5 p.m., when she heads to her second job. Without coffee, "I would feel like my day hasn't started," she says. "It gives me my jump-start for the day."
Aside from pregnancy, experts say that reasonable caffeine consumption doesn't seem to pose a threat to good health. But the caffeine in coffee is addictive, and the signs of withdrawal that coffee drinkers experience if they skip a few days are evidence of that, experts say. "We know that caffeine is the most widely used mood-altering drug in the world," says Roland Griffiths, a professor in the departments of psychiatry and neuroscience at the Johns Hopkins School of Medicine, who has studied caffeine extensively. "It is estimated that as much as 80 percent of the world's population consumes caffeine in one form or another." (Learn 6 signs of caffeine withdrawal.)
Another caution: Some studies suggest that drinking coffee may act as a trigger for heart attack among certain infrequent coffee drinkers, though more research is needed to confirm this. In any case, that potential risk is one that seems to dissipate in chronic coffee drinkers. Another: caffeine-induced spikes in blood pressure. In people who haven't been coffee-drinkers, if "they start using caffeine, you see a pronounced increase in blood pressure," van Dam says. But after a week or so, this effect is "much less pronounced than it was initially. ... There's still a bit of an elevation in blood pressure, but it's pretty modest," he says. The Nurses' Health Study, a long-running research project involving 238,000 nurse participants that looks at what influences women's health, examined consumption of coffee in relation to the development of high blood pressure and did not find a connection, according to results published in 2005 in the Journal of the American Medical Association.