This week’s New England Journal of Medicine reports on the relationship between coffee drinking and mortality in a cohort study of Americans. The study followed

229,119 men and 173,141 women in the National Institutes of Health–AARP Diet and Health Study who were 50 to 71 years of age at baseline

and this paper reports on their coffee drinking habits. Its main finding (my emphasis):

During 5,148,760 person-years of follow-up between 1995 and 2008, a total of 33,731 men and 18,784 women died. In age-adjusted models, the risk of death was increased among coffee drinkers. However, coffee drinkers were also more likely to smoke, and, after adjustment for tobacco-smoking status and other potential confounders, there was a significant inverse association between coffee consumption and mortality.

This is why we do confounder adjustment … so I can slurp down another black coffee in complete peace of mind. And check the details:

Adjusted hazard ratios for death among men who drank coffee as compared with those who did not were as follows: 0.99 (95% confidence interval [CI], 0.95 to 1.04) for drinking less than 1 cup per day, 0.94 (95% CI, 0.90 to 0.99) for 1 cup, 0.90 (95% CI, 0.86 to 0.93) for 2 or 3 cups, 0.88 (95% CI, 0.84 to 0.93) for 4 or 5 cups, and 0.90 (95% CI, 0.85 to 0.96) for 6 or more cups of coffee per day (P<0.001 for trend); the respective hazard ratios among women were 1.01 (95% CI, 0.96 to 1.07), 0.95 (95% CI, 0.90 to 1.01), 0.87 (95% CI, 0.83 to 0.92), 0.84 (95% CI, 0.79 to 0.90), and 0.85 (95% CI, 0.78 to 0.93) (P<0.001 for trend).

If we’re going on an American coffee standard, I’d say I’m drinking 6 or more cups of coffee per day, so I have a 10% reduced risk of mortality over 15 years (the rough period of the study). Sadly, though, I’m not protected against cancer:

Inverse associations were observed for deaths due to heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections, but not for deaths due to cancer.

The effect was also observed in non-smokers (that’s me!)

So, the word is in from the world’s top medical journal: the more coffee you drink, the longer you live!