I am indebted to a diligent reader for the following headlines that tortured one recent study and an unknown number of
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Australians and Indians. The first is from Perthnow.com, one of the leading sources of news in Western Australia: “Wrong amount of coffee could kill you.” How much? Not very much, it seems.
“Drinking five coffees a day - even when decaffeinated - has been linked to obesity and chronic disease by WA researchers,” said Perthnow. “It is the first study in the world to look at higher doses of coffee, rather than the equivalent of one or two cups, and it found that five coffees doubled the fat around organs in the abdomen – a type of fat that causes deadly conditions.”
Thousands of miles away, Firstpost.com – a popular Indian news portal – reported on the same research with this headline: “Drinking 5 cups of coffee everyday may lead to obesity: study.”
“The researchers found that mice given an equivalent dose of five cups of coffee for a human developed twice the amount of visceral fat — the most dangerous form of fat that collects around the organs in the abdomen,” said Firstpost.
The copy in both articles was largely identical, with overlapping expert quotes, revealing a likely dependence on a press release rather than the actual study, which was published in the Journal of Agriculture and Food Chemistry under the rather less gripping title, “Supplementation of a High-Fat Diet with Chlorogenic Acid Is Associated with Insulin Resistance and Hepatic Lipid Accumulation in Mice.”
But did you just notice something? The study is not about coffee or people, but about giving chlorogenic acid ( a polyphenolic compound found in coffee and other fruits) to mice that were on a high fat diet. And if we read the study – why not? – we learn that the increase in fat deposits around certain organs in these mice was not significant compared to the mice on a plain old high fat diet. Indeed, none of the mice in the study appear to have been killed from consuming the “equivalent” of five cups of coffee a day. They just didn’t lose weight or see a positive impact on other biomarkers for metabolic syndrome as had been previously hypothesized.
This is all very interesting in biochemical terms especially if you are a mouse; but it also means that there is absolutely nothing in the study to support any causal link whatsoever between drinking five cups of coffee a day and obesity or death in humans. Indeed, as to whether chlorogenic acid’s effects in obese mice can be extrapolated to humans – and many an effect in a mouse does not scale across species – the paper ends by saying only that “Further work especially on human intervention studies is required to determine if coffee polyphenols are able to protect against metabolic syndrome and type 2 diabetes in humans.” Note how the researchers have phrased this for a scientific journal – an absence of protection rather than a possibility of café con muerte.
So, another case of journalists mucking up scientific research by not paying attention to what the experiment can and cannot say on its own terms – something the philosopher Gary Gutting recently addressed in an excellent opinion piece for the New York Times? To a degree, yes; but the problem seems to have been exacerbated by the researchers themselves talking about their results in a way which makes them seem applicable to humans – a way that just so happens to elevate an interesting but limited study into a life-threatening news story.
