America's most popular beverage—coffee—is the No. 1 source of antioxidants in the American diet.

"That's because we drink so much of it," says Joe Vinson, a professor of chemistry at the University of Scranton and author of a new study on antioxidants in commonly consumed foods, released last week at the American Chemical Society's national conference. With a gourmet coffee shop on every corner, over half of Americans now drink coffee every day. They consume three times as much coffee per person as they do the second-most popular drink, tea, even though cup for cup, tea has more antioxidants.

Antioxidants are natural chemicals found in a variety of fruits, vegetables, spices, oils, and beverages that may reduce the risk of heart disease, cancer, and other illnesses. Both caffeinated and decaffeinated coffee contain specific antioxidants called chlorogenic acids that may improve insulin sensitivity, reducing the risk of Type II diabetes. Coffee seems to reduce rates of Parkinson's disease, too.

"But caffeine also raises your blood pressure," cautions Vinson, "and the oils in coffee raise both LDL [bad] and HDL [good] cholesterol. Coffee may be the biggest source of antioxidants, but it isn't the best. The best is fruits and vegetables, which have vitamins and minerals."

But people aren't eating enough of them. In fact, Americans get more antioxidants in that morning cup of java than in all the fruits and vegetables in their diets combined.