Can coffee make you live longer?

We hear a lot about drinking coffee and our health in the news.  The latest headlines are that “coffee drinkers live longer” and even “drinking coffee is now officially awesome for your health“! Some of the reporting has also commented on the amount of coffee involved: “five cups of coffee a day help you live longer“.  With previous reports claiming that similar amounts of coffee are bad for your health and even reduce life expectancy, what are the general public supposed to think?

What did the study involve?

The NHS Behind the Headlines team have described the nature of this study in detail in a very informative piece on the news coverage. If you want to read more about the study, I would recommend you read their article. In light of this, I will just very briefly summarise what the study involved here.

The study involved three sets of data comprising 208,501 health professionals who were followed up for more than 20 years. The researchers reported that people who drank between one to five cups of coffee a day were slightly less likely to have died by the end of the 20 year period, compared to people who did not drink coffee at all. The authors were quoted as stating that “Bioactive compounds in coffee reduce insulin resistance and systematic inflammation. That could explain some of our findings”.

As the NHS article on this study points out, however, the differences in the chance of death between those who drank coffee and those who didn’t, while statistically significant, were modest, ranging from a 5% to a 9% reduction in risk. The study also cannot show cause and effect and there could be other confounding factors (factors not examined other than coffee drinking) that could account for the results.

How did the media handle coverage of the study?

Most of the coverage was cautious using phrases such as “can make you live longer” or used question format “could five cups of coffee help you live longer?“.  Other coverage, however, made direct causal links and made the reduction in risk sound better than the reality. These included headlines such as “it’s official, coffee will make you live longer” and as described above “drinking coffee is now officially awesome for your health“. As the NHS analysis points out, casual links should not be made and the absolute reduction in risk should be considered in light of the value of engaging in other health promoting activities, such as giving up smoking, following a healthy diet, and taking regular exercise.

Headlines

Both of the methods used by the more cautious headlines – using toning down language such as ‘may’, ‘can’, ‘could’, ‘might’ or framing the headline as a question – have been key strategies school children have been using to Rewrite the Headlines in our school competition.  The competition, which is open to all primary schools in Scotland (P5-7 classes) ends on 30th November. During workshops we carried out with children, we discussed a very similar example to the current coffee study coverage. This concerned a food type very familiar to children – chocolate! In the workshops, we discussed headlines such as ‘chocolate makes you live longer’. Children changed the headline to tone it down with examples such as ‘eating a bit of chocolate can help your health’ and ‘chocolate can be good, but eating too much makes you put on weight’.

The continual media focus and contradictory changes in reports on the health benefits of food/drinks such as coffee, chocolate and red wine are very confusing to the general public. The bottom line is that moderation is always the best health advice.

Ding, M. et al. (2015). Association of Coffee Consumption with Total and Cause-Specific Mortality
in Three Large Prospective Cohorts. Circulation. DOI: 10.1161/CIRCULATIONAHA.115.017341