UNLESS - they are coffee drinking smokers.
This study caught my attention because I often hear people say they are going to stop drinking coffee and my response is always the same, "Why?"
I thought that I could read the research (summary) abstract from the study by Freedman, Park, Abnet, Hollenbeck and Sinha (N Eng Jour Medicine, May 2012) and be satisfied to give you the highlights. However, the summary doesn't answer a fundamental question - is it only regular coffee that provides a benefit?
I will get to that, but before I do - here is the bottom line.
The study involved a large sample of men and women who were enrolled by AARP. Over 80% of the sample was white, and only 6 states and 2 municipalities were represented. The people were between ages 50 and 71 at the start. The study lasted from 1995 to 2008. In 1995, people were asked questions about their lifestyle habits (including a food frequency questionnaire), disease conditions and other things, like age, gender, race, etc. All of this was self reported so there could be some mistakes. To be in this particular substudy, the people could not have had heart disease, history of stroke or cancer in 1995. At this one time only, the researchers asked them how much coffee, in cups, they drank per day.
By 2008, 14% of the 229,119 men had died and 11% of the 173,141 women had died.
When the researchers did not control for smoking, it seemed like coffee increased all causes of death - because a majority of smokers drink coffee. But in statistical analysis, a scientists can make it as though smoking didn't happen or that everyone was "the same age" so that the only difference between people is coffee consumption (they controlled for eating habits and exercise level, as well). They analyzed the results separately for men and women. When controlling for these other factors that are known to be related to heart disease and cancer and all death, coffee drinkers had a lesser number of deaths in the study period than non coffee drinkers.
When reviewing the methods in the full study, I found that over 90% of the people did answer the question "Is the majority of your coffee consumption caffeinated or decaffeinated."
The results for all death as reported by the authors, is that men who drank 6 or more cups per day had 10% less death and women had 15% less death than those of each gender who drank less than one cup a day. They also broke it down to show less incidence of specific diseases in coffee drinkers. They include a really cool graph showing coffee drinking and risk vs protection for many different diseases. For all the diseases they mention, coffee is protective EXCEPT cancer. It either increased the risk of cancer death in men and women, or was neutral, but it did not protect against it. This makes sense in my real world experience as my dearest, most beloved aunt, drank coffee from sun up to moonset, smoked just as much and died of lung cancer. I miss her a lot.
So -It is an interesting study. Not perfect - and it doesn't make causal determinations, it can't. But in this group of older white folks, coffee drinking seemed to lower risk of death from all causes and specific causes. The findings held regardless of whether the coffee drinker usually drank regular or decaf!
What you also need to hear is that it is something in the COFFEE not in the caffeine. [maybe phytochemicals] You cannot take the caffeine out of context and expect the same results (i.e. don't start drinking energy drinks, or assume that tea or soda does the same thing - it might, but this study doesn't tell us that).
Here is the link for the free summary.
Now, time for my evening decaf cappuccino.