Because it tastes so good, you may assume coffee is bad for you. Maybe you’ve heard rumors that your morning brew causes everything from heart disease to cancer. But researchers are finding that coffee poses little to no health risk for most people. Not only that, coffee drinking might have some health benefits.
Early research hinted that coffee might have some harmful effects. But most of those studies searched for links between people’s habits and their overall health. In such studies, it’s hard to know which effects come from coffee and which just show up by coincidence. Heavy coffee drinking sometimes goes hand in hand with unhealthy habits, like smoking and a less active lifestyle.
Coffee beans are seeds and, like all seeds, they’re loaded with compounds to protect the plant’s next generation. “Coffee is an amazingly potent collection of biologically active compounds,” says Dr. Walter C. Willett of the Harvard School of Public Health.
Caffeine is probably the most well-known compound in coffee. It can make you feel more awake and alert, which is why most people drink coffee in the first place. But too much can be harmful. In fact, according to Willett, caffeine causes the most common problem reported by coffee drinkers: trouble sleeping. Caffeine can also blunt your appetite and cause headaches, dizziness, nervousness and irritability.
If you’re sensitive to caffeine, Willett says, simply drink less of it. If you have trouble falling asleep at night, make sure to avoid it later in the day.
Caffeine is mildly addictive, so you might get headaches, drowsiness, irritability, nausea and other symptoms if you suddenly cut back. You can avoid these effects, though, by gradually reducing your caffeine intake.
“There’s some evidence that high amounts of caffeine during pregnancy may cause problems with the pregnancy,” says Dr. Jared Reis of NIH’s National Heart, Lung and Blood Institute. That’s why doctors recommend that pregnant women cut back on coffee and other caffeinated beverages.
Studies also suggest that caffeine may interfere with calcium absorption. Calcium is an important nutrient for growing and maintaining strong bones. Make sure you get enough calcium in your diet to help reverse this effect.
Overall, says Dr. Rob M. van Dam of Brigham and Women’s Hospital and Harvard Medical School, “Caffeine doesn’t seem to have the wide array of detrimental health effects we first thought it had.”
At one time, many doctors worried that coffee might cause cancer. That’s largely because caffeine damages DNA in the test tube, Willett explains, and DNA damage is linked to cancer. However, that doesn’t mean that coffee causes cancer in people. Coffee also has high levels of compounds, called antioxidants, that protect DNA.
“Coffee’s been looked at in detail in relation to many cancers, and there’s really not been any good evidence that any type of cancer is increased by coffee consumption,” Willett says. “I think we can say quite confidently that there’s no increased risk of cancer with coffee consumption.”
Some evidence even suggests that coffee may help reduce the risk of liver cancer, Willett says. NIH’s National Cancer Institute is now organizing a new effort to put together data from many studies and look into this question, among many others.
Some doctors thought coffee might cause heart attacks or strokes, because caffeine can raise blood pressure. But Reis says that a cup of coffee won’t lead to a dramatic increase in blood pressure for regular coffee drinkers. “In long-term studies, higher levels of caffeine have not led to a higher risk of cardiovascular disease,” he says.
Some types of coffee can cause cardiovascular problems for another reason, however. Coffee can contain compounds that lead to a rise in LDL cholesterol. That’s the “bad” kind of cholesterol that’s been linked to cardiovascular disease.
“A lot depends on the way in which coffee is brewed,” Reis explains. “When coffee is brewed with a paper filter, it removes a lot of the components that lead to higher LDL.” So it’s a good idea to drink filtered coffee to avoid this problem.
Coffee may even have some positive effects. Some studies have linked coffee intake with a lower risk of developing Parkinson’s disease. “When looking at Parkinson’s disease patients, they may be up to 4-8 times less likely to have been heavy coffee drinkers,” says Dr. Wendy R. Galpern of NIH’s National Institute of Neurological Disorders and Stroke. However, she points out, the studies in this area have been limited. “It’s hard to know if this is just an association or if this is cause and effect,” she says.
Some studies suggest coffee may have other positive effects on the mind. Galpern says that researchers are now looking into the potential effects of caffeine on memory and Alzheimer’s disease.
Perhaps the strongest research showing a health benefit from coffee relates to type 2 diabetes. In a 2002 study, van Dam’s team reported that people drinking 7 or more cups per day had a 50% lower risk of type 2 diabetes than those drinking 2 or less cups. About 20 studies have now looked into the effect in various populations. “The great majority of studies confirm that coffee is associated with a lower risk for type 2 diabetes,” van Dam says.
Researchers aren’t sure why coffee has this effect, but some compound other than caffeine is responsible. “We did a study of decaffeinated coffee and essentially found the same association as caffeinated coffee,” van Dam says.
Another potential benefit from coffee is that it can keep you from drinking less healthy things. “We think that coffee is actually quite a good beverage compared to other beverages,” van Dam says. “It can be a reasonable beverage choice if you don’t add a lot of cream and sugar.”
Coffee can also help your social life, if you meet good friends to talk over coffee. Studies have clearly shown that people who have more social relationships have less stress and live longer. Research also suggests they’re less likely to show mental declines as they age.
So go enjoy that cup of coffee. It’s not the guilty pleasure you may have thought.