Go ahead, have that extra cup of coffee.
One of the largest studies ever conducted shows that coffee drinkers die at almost the same rates as their non-drinking peers. But, after controlling for the fact that coffee drinkers tend to exercise less and smoke more, coffee is linked to a slightly lower death rate in both men and women.
The findings, reported in the June 17 Annals of Internal Medicine, are based on data from the Nurses Health Study and the Health Professionals Follow-up Study. The two studies tracked 86,214 female nurses for 24 years and 41,736 male veterinarians, pharmacists and other health workers for 18 years. Every two years, the volunteers answered detailed questionnaires about coffee consumption, exercise habits, weight, smoking history and other health information.
Overall, participants who downed a few cups of coffee a day had about the same death rate as those who didn’t drink coffee, despite the fact that coffee drinkers tended to smoke more, drink more alcohol, not take vitamins and exercise less. All of those factors are linked to higher death rates.
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After accounting for the caffeinated coffee drinkers’ less healthy lifestyles, the researchers found that women drinking two to three cups a day had a 25 percent lower death rate from heart disease and an 18 percent lower risk of death from all causes compared with their equally unhealthy peers. The study did not find such differences for men, perhaps because the study tracked fewer men for a shorter period of time, says Esther Lopez-Garcia of the University Autónoma of Madrid in Spain, who led the study. Volunteers who drank caffeinated and decaffeinated coffee had similar death rates, suggesting that caffeine was not responsible for the beneficial effect.
The death rates of those who drank even higher amounts of coffee did not differ significantly from the death rates of volunteers who drank 2 to 3 cups of coffee a day.
The findings suggest that coffee may reduce the risks of death in general, and may be especially good at combating heart disease.
David Jacobs, an epidemiologist at the University of Minnesota in Minneapolis who was not involved in the study, says the results are convincing. “People like to sit down with a cup of coffee and a cigarette. That really confounds the data, but they have really nice analyses of smoking status and coffee.”
Ken Mukamal, an internist at BethIsraelDeaconessMedicalCenter in Boston, agrees. “They have very careful and detailed information on lifestyle features,” he says. “It’s important . . . to take these results at face value.”
The idea that coffee can promote health isn’t far-fetched, Mukamal says. Coffee beans are chock-full of antioxidants, chemicals that can protect DNA from damage and promote cell survival. What’s more, coffee may also reduce inflammation inside the blood vessels, thereby lowering the risk of heart disease, Lopez-Garcia says.
Still, it’s premature to start guzzling coffee as a health tonic, she says.
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Studies on coffee consumption and health have had mixed results over the years. Early studies linked coffee consumption to pancreatic cancer, and others have found elevated risks of heart disease. However, those studies did not account for the fact that coffee drinkers, in general, tend to have less healthy lifestyles, Lopez-Garcia says.
“There’s very little evidence that coffee itself is a bad thing. It’s gotten a bit of a bum rap,” says Mukamal, who has been involved in other epidemiological studies on coffee and mortality. “There’s a little bit of a legacy of thinking there’s something sort of hedonistic about drinking coffee, and I don’t think it’s all that warranted.”
Just any old coffee drink may not do. The volunteers in the study, who were tracked mostly in the late 1980s and early ’90s, likely drank primarily filtered drip coffee. But past studies have shown that the health effects of coffee may depend on how it’s made, Mukamal says.
Boiled drinks like Turkish coffee and French press have high levels of a cholesterol-boosting compound called cafestol. And “coffee drinks” like mocha triple venti lattes are full of calories, which may offset any benefit of the coffee itself, he says. By contrast, filtered drip coffee, which most of the survey respondents consumed, has few calories and almost no cafestol.
The study is probably “saying something about filtered, good old-fashioned 1980s and 1990s coffee and not saying very much about the fancy kinds of coffee that you might be drinking in 2008,” Mukamal says.