This Los Angeles Times story was one of many news outlets to report on a pair of large epidemiological studies on coffee-drinking and mortality. And like many of those other stories, this piece seems to assume that coffee really is healthy, although that is not proven by these or any other observational (association) studies. We think the helpful notes of caution included in the story may get drowned out by the optimistic framing of the headline and lead paragraph. Describing coffee as “good for you” suggests to readers that coffee causes health benefits — not something that these studies were designed to evaluate.
We also explored the problems with news coverage about this study in a blog post.
As the article states, “2.25 billion cups of coffee are consumed” each day around the world. Coffee is widely consumed and many people drink multiple cups per day. The potential health benefits and risks of coffee, like its consumption cousins wine and chocolate, seem to always be of interest to health news readers. And yet, like so many previous studies, these describe an association, not a causal effect. This particular article did not claim that coffee helps you live longer, but it also did not make crystal clear that the associations found in the studies do not really tell us much about whether coffee does anything at all with regard to chronic disease or mortality.
There’s little need to discuss costs of a substance as well known as coffee.
The story does a good job of describing groups for comparison: coffee-abstainers, light drinkers (1-6 cups per week), and heavier drinkers (>2 cups per day). However death rates were presented as relative risk. How many of the 18,000-plus subject died during the average 16 years they were followed? What does “18% less likely to have died” look like in absolute numbers?
Coffee does have adverse effects, such as insomnia, increasing anxiety, and triggering reflux in certain people. However, the story made no mention of coffee’s downsides.
The story makes clear how large the study was, what the methodology was, and that other big risk factors for early death such as smoking were taken into account. Also, the story makes clear that no one is recommending coffee-drinking as a mode to prevent chronic diseases that lead to early death. And it includes a clear caution regarding the limitations of observational studies:
“Though the two studies involved hundreds of thousands of people, they weren’t designed to show that drinking more coffee caused people to live longer; that would require a randomized trial.”
And yet, it’s important for journalists to avoid language that undercuts this important message. The headline, suggesting that coffee is “good for you” makes a clear cause-and-effect leap. And the use of a hedge like “might” in the following sentence isn’t enough to offset the clear cause-and-effect implication — i.e. that coffee is responsible for “extending” your life.
“The best thing about your coffee habit might be that it extends your life by reducing your risk of death from heart disease, diabetes or even cancer.”
We’ll rate this a very marginal Satisfactory with room for improvement. Coverage at the BBC, for example, was more successful at capturing the nuances of observational evidence, starting with the headline: “Coffee drinkers live longer – perhaps.”
No fear-mongering here.
The story includes perspective from an editorial that accompanied the studies in the journal, the Annals of Internal Medicine. And that’s enough for a satisfactory grade. Reaching out to more sources, and actually talking to experts in this field, might have turned up additional insights worth sharing with readers.
The story makes clear that the claims of benefit — reduced mortality — are not a reason to drink coffee. Instead the findings suggest there are no long-term effects that should scare coffee-drinkers away from their habit. In any case, the situation does not call for a comparison with alternative methods of living longer. We’ll rate this Not Applicable.
Coffee is so widely available that there’s no need to make the point.
The story makes clear how the National Cancer Institute study extends previous research on coffee’s health effects from studies of mostly white European-descent subjects to a multi-ethnic population.
The story does not appear to rely on a news release.