Two studies publishing in the Annals of Internal Medicine assess the association between higher coffee consumption and reduced risk of death | Science Media Centre
“These two studies followed many thousands of people for 16 years and compared death rates in coffee drinkers with non-coffee drinkers. In keeping with previous studies, death rates were slightly lower in coffee drinkers than in non-coffee drinkers.
“The studies were well conducted and have the advantage of having observed thousands of people from many different countries and ethnic backgrounds, and the association between coffee drinking and mortality seems to be the same across all these populations.
“The authors of both studies are commendably cautious about whether or not coffee drinking is the cause of the reduced mortality in coffee drinkers, or whether there are other unknown differences between coffee drinkers and non-coffee drinkers that are the real cause for the differences observed. Neither study seems to take into account the income of the people involved (although they do adjust for educational level) and since coffee isn’t cheap it is possible that non-coffee drinkers are less well off, which would be a potential explanation for some of the differences seen.
“What can we conclude from these studies? The authors of both papers sensibly go no further than concluding that their results show that coffee drinking is not harmful. I’m occasionally asked by patients whether they should drink coffee and these studies will help in advising them that coffee drinking is safe.
“The only way to be certain whether or not coffee might make people live longer is to force many thousands of people to drink it regularly, while preventing many thousands of otherwise similar people to never drink coffee. A study like this is never going to take place, so we may never know the answer to this question.
“I don’t think this study should lead anyone to drink more coffee in search of a health benefit that might not actually exist. It is useful to compare this to the proven benefits of physical activity. A 20-min walk to a local coffee shop will definitely provide many health benefits, even if you don’t actually go in and buy anything.”