Guess the hype around the Mediterranean diet was really just unnecessary, huh?

Here’s the thing: back in 2013, the diet was lauded by the boffins from the New England Journal of Medicine.

They published a study that found that people put on a Mediterranean diet had a 30% lower chance of heart attack, stroke, or death from cardiovascular disease than people on a low-fat diet.

Sounds like the perfect diet, which got a lot of attention from mass media and other boffins.

Except the journal has now retracted the study, a report by Quartz explains.

They did so on Thursday, providing a new yet complicated reason for scepticism about how effective the now-popular Mediterranean diet really is.

As Alison McCook of the Retraction Watch blog writes for NPR, this retraction is the result of the work of John Carlisle, a British anesthesiologist and self-taught statistician. Carlisle has spent recent years analyzing over 5 000 published randomized [sic] controlled trials (the gold standard of medical science research) to see how likely they were to have actually been properly randomized.

In 2017, he reported his results: at least 2% of the studies were problematic.

One of these was the 2013 NEJM article on the Mediterranean diet.

That’s a bugger-up of epic proportions right there.

The lead author of the paper, Miguel Ángel Martínez González, saw Carlisle’s analysis and decided to follow up with a thorough review of the study design:

The study was supposed to randomly assign participants to either the Mediterranean diet with a minimum of four extra tablespoons of olive oil a day, the same diet but with at least an ounce of mixed nuts, or a low-fat diet. But Martínez González found that of the approximately 7 500 participants in the study, 14% had not actually been randomly assigned.

Instead, many married couples were assigned to the same group. In one particularly troubling case, a field researcher decided to assign an entire village to a single group, because some residents were complaining that their neighbors were getting free olive oil. The field researcher working never reported the decision.

I can sort of understand why, since it would have been hella awkward to explain that a couple of residents were irate about not getting in on the olive oil action from the start:

Martínez González and his team spent a year reanalyzing [sic] the data, working with outside experts. The end result is that the study’s overall findings are still accurate in one sense: There is a correlation between the Mediterranean diet and better health outcomes.

But in another sense, the paper was entirely wrong: the Mediterranean diet does not cause better health outcomes.

*Insert dramatic music* Shock and horror.

It just goes to show how flawed the Mediterranean diet is, which is a huge blow to its public perception. Not to mention the NEJM boffins must be feeling awkies AF.

Moral of the story: even scientists can get stuff wrong.

[source:quartz]