How and why do so many health myths transform into everyday wisdom? Perhaps because academic press releases are exaggerated or misrepresented when they're written up in news stories.
The goal of a press release around a scientific study is to draw attention from the media, and that attention is supposed to be good for the university, and for the scientists who did the work. Ideally the endpoint of that press release would be the simple spread of seeds of knowledge and wisdom; but it's about attention and prestige and, thereby, money. Major universities employ publicists who work full time to make scientific studies sound engaging and amazing. Those publicists email the press releases to people like me, asking me to cover the story because "my readers" will "love it." And I want to write about health research and help people experience "love" for things. I do!
Across 668 news stories about health science, the Cardiff researchers compared the original academic papers to their news reports. They counted exaggeration and distortion as any instance of implying causation when there was only correlation, implying meaning to humans when the study was only in animals, or giving direct advice about health behavior that was not present in the study. They found evidence of exaggeration in 58 to 86 percent of stories when the press release contained similar exaggeration. When the press release was staid and made no such errors, the rates of exaggeration in the news stories dropped to between 10 and 18 percent.
Even the degree of exaggeration between press releases and news stories was broadly similar.
One golden rule: never believe a press release.
Of course, since most research papers I encounter online are behind a paywall, it's difficult to compare them to the news stories representing them. Why are so many research papers paywalled? I can't imagine the revenue to be more than a trifle so why not just let more eyeballs at it to amplify one's fame instead? Perhaps someone with more knowledge of that world can explain the economics.