It’s not the first thing you’d expect to see in a health food store, but coffee might actually be good for you.

In the American heartland, high school students huddle over free coffee refills in a chain diner, the only place away from home where they can hang out in the middle of the night. At a truck stop in the Southwest, a woman takes a big gulp of stale black coffee before starting up her rig. In the Northeast, an elderly man wakes his wife with the aroma wafting from their weathered percolator. From the nerve-jangled caffeine addict to those who have a mug once a week, month, or even year, a lot of people drink coffee. But is it healthful?

John Mackey, the founder and CEO of Whole Foods natural products superstores, recently told the press that he reluctantly agreed to sell coffee — along with meat, seafood, beer, and wine — because he considers such foodstuffs unhealthful. Consumer Reports has warned that “heavy coffee drinkers, pregnant women, and possibly people with heartburn, breast lumps, or anxiety disorders may benefit from cutting back on the brew.” A 2000 Finnish study linked coffee consumption to an increased risk of developing rheumatoid arthritis, though a 2003 Harvard Medical School study did not find a connection.

Joseph F. DeRupo, director of communications for the National Coffee Association, says, “The scientific evidence coming out of labs around the world is almost entirely positive [on coffee’s healthfulness]. It’s absolutely clear that coffee has a protective effect against type 2 diabetes. We think it has to do with a chemical unique to coffee that affects sugar uptake in the liver. Coffee also protects against colon and rectal cancers.” Researcher Tomas dePaulis of Vanderbilt University’s Institute for Coffee Studies, which receives funding from the coffee industry, adds, “Japanese studies have found that coffee also helps protect the liver, particularly for those who drink alcohol and smoke tobacco.”

DeRupo argues, “Coffee does not have a negative effect on a healthy pregnancy.” He says a study that suggested a link to miscarriages ignored other factors including tobacco and alcohol intake. However, the FDA advises pregnant women to drink coffee in moderation. Although coffee does stimulate the cardiovascular system and could increase blood pressure (though not nearly as much as salt), a 2002 Swiss study suggested regular drinkers could become immune to the effects.

Researchers think some of coffee’s purported health benefits could come from its generous dose of antioxidants, which fight damage to cells. “Americans get more of their antioxidants from coffee than any other dietary source,” Joe Vinson of Pennsylvania’s University of Scranton recently reported after studying the issue. Vinson says coffee isn’t the best source of antioxidants, though it’s convenient. “One particular antioxidant that’s unique to coffee may protect against gallstones, Alzheimer’s, and Parkinson’s,” says DeRupo.

Coffee is a complex mix of hundreds of compounds, many of which are poorly understood by science. Even the ingredient that takes its name from coffee — caffeine — puzzles researchers, despite years of investigations. Recent studies have linked caffeine to increased athletic performance, stamina, and mental acuity. “Caffeine is classified as a stimulant, but its effects come from a different mechanism than cocaine or amphetamines, and it is not addictive the way those stimulants are,” says dePaulis. “Caffeine is addictive on a cellular level, in that your blood vessels get addicted, which explains the headaches and other withdrawal symptoms when you quit.”

“Coffee is a health food, and my personal view is that anyone can drink as much as they can stand,” says dePaulis.

But even though coffee might be good for your liver, according to DeRupo, the notion that the drink can sober up drunks seems to be a myth.