Though many refer to their java habit as an unhealthy indulgence, experts say that in moderation, a cup or two of joe a day actually has numerous health perks.
"People always talk about it as if it's a little bad for you. That's not necessarily true," says Donald Hensrud, associate professor of Preventive Medicine and Nutrition at the Mayo Clinic. "Coffee contains over 2,000 different chemical components, including cancer-fighting anti-oxidants."
Some studies suggest coffee can boost vision and heart health, says registered dietitian Elisa Zied, author of Nutrition at Your Fingertips. Research also has suggested coffee helps people with liver disease, but it has had mixed results when it comes to diabetes.
But be aware of how much caffeine you're consuming, because it varies among coffee drinks, says Mary Rosser, assistant professor of obstetrics and gynecology at Montefiore Medical Center in the Bronx, N.Y.
Loading up on cream and sugar is a bad idea, Hensrud says. A Starbucks venti 24-ounce double chocolate chip frappucino has 520 calories, 14 grams of saturated fat and 75 grams of carbohydrates. Pregnant women and people with anxiety and sleep problems should especially watch their intake, he says.
Also, people metabolize caffeine differently — the result of genetic differences, Hensrud says.
Caffeine's influence can last for 10 hours or more, says researcher Jim Lane, a professor of medical psychology at Duke. He recommends pacing yourself throughout the day: "It's nice to have places to meet friends that aren't alcohol-related, but it does sort of encourage people to ignore the drug effects of caffeine."
More on coffee's perks and pitfalls:
Aging Recent research suggests caffeine could help protect against cognitive decline, including Alzheimer's disease and other dementia, says Mayo's Hensrud. Large clinical trials are still needed, though, says Duke aging expert Murali Doraiswamy. "We still don't know the right dose for seniors," Doraiswamy says. "Bottom line: I would not recommend caffeine solely as a preventive strategy for dementia."
Wakefulness/performance Convinced you need a morning cup to wake up? Research online this month in Neuropsychopharmacologysuggests frequent coffee drinkers develop a tolerance to the anxiety-producing and stimulatory effects of caffeine. A study last month suggests those who consume caffeine perform better on the job.
Dental Coffee exacerbates bad breath, Zied says. It also can give teeth a yellow tinge.
Diabetes Although research suggests drinking five or six cups a day might reduce the risk of developing type 2 diabetes, other studies show caffeine can exaggerate blood sugar problems in people who already have it, says Duke's Lane.
Gastrointestinal High levels of caffeine can exert a laxative effect in some people but constipate others, Zied says. Heartburn and peptic ulcer patients should steer clear, too.
Heart Too much coffee at once can increase blood pressure, but a cup or two a day generally does no harm to heart health, says Carl Lavie, medical director of Cardiac Rehabilitation and Prevention at John Ochsner Heart and Vascular Institute in New Orleans. Rarely, overindulgence can increase heart rate and cause heart rhythm disturbances, he says.
Liver "Coffee intake is associated with a reduced risk of cirrhosis and liver cancer," Hensrud says.
Migraine Hensrud says coffee can ease migraines in some people. Coffee lovers who drink at work each day should keep up the habit on weekends, because skipping coffee can lead to withdrawal headaches, he says.
Mood Too much coffee can increase anxiety, Zied says, especially in people who are prone to panic attacks. Lane has done studies showing that caffeine ups adrenaline and stress, especially if the body is already under stress.
Pregnancy The March of Dimes and the Food and Drug Administration recommend no more than 200 milligrams of caffeine a day for pregnant women and nursing mothers, says Montefiore obstetrician Rosser. More can affect babies in utero — increasing the heart rate and possibly slowing fetal growth. Trying to get pregnant? Same recommendation. But if infertility is a concern, avoid coffee.
Sleep The caffeine in coffee is a stimulant. It can make you jittery and contribute to insomnia, says sleep expert Craig Schwimmer, medical director of The Snoring Center in Dallas. "It's all in how you use it," he says, explaining that caffeine has a half-life of about six hours. A couple of cups in the morning is fine, but for those with sleep troubles, cut coffee at least six hours before bedtime.