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Study: Heavy coffee drinking in people under 55 linked to early death

Georgiann Caruso and Elizabeth Landau | 8/20/2013, 6 a.m.
When you make coffee with breakfast, or grab a to-go cup at a cafe before work, or raid your office's ...

— When you make coffee with breakfast, or grab a to-go cup at a cafe before work, or raid your office's break room for a cup in the afternoon, you're probably not thinking about how scientists are studying it.

So we'll just tell you: Many studies have looked at the health effects of coffee, even though measuring the potential harms and benefits is not as easy as chugging a shot of espresso. Since a whole range of lifestyle and genetic factors influence a person's physical well-being, it's hard to know exactly if, or how, or to what extent, coffee would be good or bad for anyone's longterm health.

The latest study, published in the journal Mayo Clinic Proceedings, found an association between drinking more than 28 cups of coffee a week and an increased risk of death from all causes, in people 55 years old and younger. One cup of coffee is 8 ounces.

That doesn't prove that coffee causes death. It also seems to contradict a study in the New England Journal of Medicine last year, which found that people who drink two or more cups of coffee a day have a reduced risk of dying from particular diseases than those who consume little or no coffee.

And a May 2011 study found that men who drink six or more cups a day had a decreased risk of fatal prostate cancer.

How are we supposed to decide how much coffee to drink, when the information about its health effects is more confusing than a cafe menu written in a foreign language?

Experts say that the optimal dose of coffee varies widely, depending on the person. Different people have different tolerances for coffee.

But in general, the authors of this new study emphasized a message of moderation.

The new study

Researchers followed more than 40,000 people ages 20-87 for about 16 years.

They observed risks for heavy coffee drinkers in both men and women under 55 who drank more than four cups of coffee a day on average. In men who fit this description, the risk of death was 56% higher compared to non-coffee drinkers. In women, the risk was even greater -- it doubled, compared to non-coffee drinkers.

The same association was not observed in individuals 55 and older, or in people who drank coffee in moderation.

"It appears that low doses of coffee are safe," said Carl J. Lavie, study co-author from the John Ochsner Heart and Vascular Institute in New Orleans. "We did not see anything bad happening up to about 28 cups per week."

He added, "no increase in cardiovascular mortality at any dose in men or women at any age" was seen.

Caveats

But wait! Although study authors found a connection between heavy coffee consumption and death, they did not prove that frequent java indulgence causes death. There may be other underlying factors that explain this association.

"What if people are super hyper, driven, stressed out, drinking 10 cups of coffee a day?" Lavie said. "And it's not the coffee that's killing them, it's the fact that they're stressed out that's killing them."