Wednesday, February 19, 2025

June 15, 2018

Turns Out The Mediterranean Diet Is A Load Of Crap

The Mediterranean diet seemed like the world's answer to dealing with weight gain and heart disease, but you can toss that in the bin now.

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]