The latest findings on coffee suggest that it even staves off disease. Caffeine reduces the risk of Parkinson's disease, for example, by blocking receptors for adenosine, a neurotransmitter that plays a role in motor function. It is now being tested as a Parkinson's treatment. Caffeine also heads off migraines by contracting blood vessels in the brain.
And probably because coffee, like blueberries and broccoli, contains potent antioxidants, it appears to reduce the risk of colon cancer, gallstones, and liver cancer, among other illnesses. In 2005, Harvard researchers found that drinking six cups of coffee or more daily cut the risk of getting type 2 diabetes by half in men and 30 percent in women. One study of 80,000 women showed that those who drank more than two or three cups of coffee daily reduced their risk of suicide over 10 years by a third.
Alas, that glorious rush of energy isn't entirely benign. Numerous studies have found no link between caffeine and cardiovascular disease. But it can cause anxiety, jitters, and heart palpitations, particularly in people who are sensitive to it. It also can cause stomach pain and gastrointestinal reflux, may make it harder for a woman to get pregnant, and may increase the risk of miscarriage or a low-birth-weight baby. Doctors advise pregnant women to give up caffeine, or keep consumption down to a cup or two of coffee daily.