Coffee lovers who drank 5 or more cups of caffeinated coffee a day had a 40 percent decreased risk of brain cancer, compared with people who drank the least. A 5-cup-a-day coffee habit reduces risks of oral and throat cancer almost as much. Researchers credit the caffeine: Decaf had no comparable effect. But coffee was a more potent protector against these cancers than tea, which researchers said also offered protection against brain cancer. There also seems to be evidence that coffee can prevent Alzheimer's disease as well. So drink up!