Sifting through the risks and benefits of coffee.

Health and medicine explained.
July 27 2011 7:24 AM

Café or Nay?

Some studies say coffee is good for you; others say it's bad. The scientists are just as confused as we are.

Cappucino. Click image to expand.

Coffee is one of those things that make curmudgeons like Andy Rooney throw up their hands. They used to tell us coffee is bad for us, he complains. Now they say it's good. Why should we believe any of it?

Rooney's complaint about the back and forth nature of coffee studies is no exaggeration. An analysis published last year concluded that coffee consumption may increase the risk of lung cancer. Yet a study published in June found that heavy coffee drinking was associated with a 60 percent decrease in the risk of advanced prostate cancer, and another out this month shows that coffee drinkers are less likely than abstainers to harbor antibiotic-resistant bacteria in their nasal passages.

In the last decade alone, scientists have published hundreds of papers attributing both harms and health benefits to coffee. What gives?

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The Starbucks generation isn't the first to find itself bombarded with conflicting stories about coffee's wholesomeness. While epidemiological studies of coffee are a modern invention, the angel/devil messages they've turned up are as old as the brew itself. Coffee, with its dark color, strong flavor, and mind-altering properties, has always aroused awe and suspicion in cultures that encountered it, says Mark Pendergrast, author of Uncommon Grounds: The History of Coffee and How It Changed the World.

According to Pendergrast's book, coffee has stimulated intellectual and often irreverent pursuits among users throughout the ages, often sparking backlash. One governor of Mecca banned the drink after discovering satirical musings about him coming from local coffeehouses. In 1674, a group of London women grew angry with their husbands for spending so much time at coffeehouses (often in an attempt to sober up after the pub), and published a pamphlet warning that the beverage would make them impotent. The men fought back with a competing pamphlet claiming that coffee actually added a "spiritualescency to the Sperme." In 1679, French doctors blasted coffee, because it "disaccustom[ed] people from the enjoyment of wine."

Pendergrast traces modern health concerns about coffee to 19th-century inventor C. W. Post, maker of the cereal drink and coffee substitute Postum. Ads for Postum warned of coffee's health dangers, which purportedly included "coffee heart," "coffee neuralgia," and "brain fag." Post's claims never had any science behind them, but in the 1960s and early '70s epidemiological studies linked coffee to breast lumps, heart disease, and bladder cancer. Those early studies didn't hold up either, but they did spur a resurgence of anxiety about America's favorite morning drug, now phrased in the contemporary language of public health.

Some of the current research does imply that coffee is bad for you. An analysis of more than two dozen studies concluded that coffee drinkers had about a 20 percent increased risk of developing urinary tract cancer, and a 2010 meta-analysis found that heavy coffee drinking may raise lung cancer risk. Women who drink coffee tend to have lower bone density and an increased risk of fractures compared with nondrinkers, and numerous studies show that coffee increases blood pressure.

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