We examined the association of coffee drinking with subsequent total and cause-specific mortality among 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. Participants with cancer, heart disease, and stroke were excluded. Coffee consumption was assessed once at baseline.
Large multi-year observational study on coffee and mortality. As always, one study is not enough to make big changes, and observational studies tend to show correlation, not causation. That said, this is yet another in a long line of studies showing coffee's positive health effects -- in some cases, very strong effects. This particular study showed that it does not matter whether it's caf or decaf, drinkers of either saw lower risk of mortality.
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.
Interpretation: At first, it looked like coffee drinkers were more likely to die, but when adjusted for other risk factors like smoking, it was found coffee drinkers were less likely to die. Of course, without knowing exactly which confounders were adjusted for, we can't be totally sure they didn't hand-pick the data to show desired results.
In this large prospective study, coffee consumption was inversely associated with total and cause-specific mortality. Whether this was a causal or associational finding cannot be determined from our data. (Funded by the Intramural Research Program of the National Institutes of Health, National Cancer Institute, Division of Cancer Epidemiology and Genetics.)
I assume this means that the study wasn't funded by the coffee industry...