Caffeine prevents recovery headaches.

Eighty percent of the people in the U.S. regularly consume caffeinated drinks. Cutting off that supply of caffeine before surgery can trigger what is known as a caffeine withdrawal headache. Research from the Mayo Clinic, Scottsdale, Ariz., finds that caffeine given to a patient intravenously after surgery can diminish or eliminate withdrawal headaches. These findings confirm an earlier Mayo Clinic Scottsdale study that showed such headaches might be prevented by patients drinking a caffeinated beverage several hours before surgery.

According to anesthesiologist Joseph G. Weber, "Liquids leave the stomach so quickly that for most people it's probably not a problem to have eight ounces of a caffeinated drink no less than two hours before surgery." Prohibiting any intake of solid food remains the norm, though. While many health care professionals continue to advise patients not to consume liquids for several hours before surgery, one-half to two-thirds of American hospitals and surgical centers have revised their policies regarding fluid intake, he says.

The earlier Mayo Clinic Scottsdale study showed that regular coffee drinkers who consumed...