Coffee is earning a better reputation on the health front as a result of several studies. In summer 2005, Harvard School of Public Health researchers evaluated studies including almost 200,000 people and concluded that coffee drinkers were less likely to develop diabetes than people who didn't drink coffee. A couple months afterward, two reports suggested that coffee blunts spikes in blood pressure due to mental stress and makes people more alert by perking up the brain's short-term memory center.
At about the same time, University of Scranton chemists reported that coffee beat out fruits and vegetables as the number one source of antioxidants for Americans. It turns out that a cup of coffee delivers a decent jolt of potentially protective antioxidants along with caffeine and hundreds of other substances. And since we drink so much — the average American has three cups a day — the antioxidants add up.
And in early 2006, more good news came from a Harvard-based study of more than 150,000 female nurses. Over the 12 years that researchers followed the women's health, habitual coffee drinkers didn't develop high blood pressure any more often than women who didn't drink coffee. In fact, women who drank three or more cups a day were 7%–12% less likely to have developed high blood pressure.
There was a hint of bad news for people who prefer decaffeinated coffee. A study presented at the American Heart Association's fall 2005 meeting randomly assigned coffee drinkers to three to six cups of caffeinated or decaffeinated black coffee a day. The researchers saw complex changes in blood fats and cholesterol among the decaf drinkers that could tip the balance toward heart disease. This result, and what it means for long-term health, need further study before anyone who drinks decaf should feel the need to abandon it.
February 2006 update