A Major Study on the Mediterranean Diet Was Retracted — but the Findings Still Hold Up, Experts Say

In April 2013, a major study was published in the well-respectedNew England Journal of Medicine(NEJM), concluding that eating a Mediterranean diet supplemented with olive oil caused a 30 percent lower risk in heart attacks, stroke, and death from cardiovascular disease compared with a low-fat diet.

The findings from the paperwere held up as one strong example of how the style of eating — rich in fruits, vegetables, fish, whole grains, legumes, and moderate wine consumption — can improve health and longevity.

为了震惊许多读者和健康专业人士，这项研究（称为预测的审判）最近缩回了NEJMfor fraudulent data used in the results, raising the question: Isthe Mediterranean dietall it’s cracked up to be for health andwellness? Long story short: Yes. But the retraction still matters, say researchers who weren’t involved in the study.

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A Closer Look at Why the Mediterranean Diet Study Was Retracted

One of the research associates on the retracted study, Yoshitaka Fujii, has been called out regarding the validity of the data he provided. It’s not the first — or 50th— time his work has been panned. In 2012, he was found to have fabricated data on 100 research papers, according toRetraction Watch, earning him the moniker “most prolific fraudster” in medical science. By 2015, thenumber of his retracted papershad reached 183.

The current retraction sprang from astatistical analysis published in June 2017by John Carlisle, of Torbay Hospital in the United Kingdom, who took various papers Fujii was involved in and analyzed the likelihood his data had actually been randomized. Randomization in research trials is necessary to determine if there is a cause-and-effect relationship between two factors, to eliminate the possibility that something else could be responsible for a study's results. In considering the data set Fujii supplied to PREDIMED, Carlisle found that it was highly unlikely to have been randomized.

While Carlisle’s analysis has resulted in many of the researcher’s papers being retracted, theNEJMarticle is noteworthy, especially in health research. In the study, the randomization groups allowed researchers to attribute the outcomes directly to the diet, which strengthens the results. Many studies looking at food intake and health outcomes rely on dietary recall, which isn’t as credible.

What the Updated Study Suggests About the Benefits of the Mediterranean Diet

Inthe new article — published on June 13, 2018— the authors note that after learning of the inconsistencies from Carlisle’s report, they withdrew their previous study, reran the data, and revised the findings. Of the 7,447 initial participants, they excluded data from 1,558 of them because of fabrication. The new results: Those who ate a Mediterranean diet supplemented with olive oil or nuts enjoyed about a 30 percent reduction in cardiovascular events compared with the low-fat group.

Put differently, the results are just about the same. “The general findings and conclusions of the PREDIMED study remain intact,” saysAlice H. Lichtenstein, a senior scientist and the director of the Cardiovascular Nutrition Laboratory at the Tufts University Jean Mayer USDA Human Nutrition Research Center on Aging in Boston, who was not involved in the research. “The study authors took the appropriate steps of reanalyzing the data and informing the scientific community of the situation. As a result of the reanalysis, the findings and interpretation of the data were virtually unchanged,” she says.

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There's been another small shift: in the language describing the results. Rather than assert a cause-and-effect relationship, the authors write that there’s an “association” between these types of supplemented Mediterranean diets and lower cardiovascular risk. “Because randomization procedures were inadvertently violated in this trial, the authors have softened their language, presumably to satisfy editorial requirements,” says大卫卡茨博士英里, the founding director of Yale University’s Yale-Griffin Prevention Research Center, who also wasn’t involved in the study. “But when they reanalyze the data using only the properly randomized participants, the same association was observed, suggesting [it's] as much ‘cause-and-effect’ as it ever was,” he adds.

The bottom line, says Dr. Katz: This story really isn’t about the diet at all, but rather “the policing of the scientific literature by scientists,” he says.

And clearly, that’s not a bad thing. “I think the scale of the problem in the PREDIMED study was sufficient to warrant retraction — I was surprised by the extent to which the intended random allocation process had been compromised (without the authors knowing),” Carlisle says. Doing these checks is important, he says, as scientists understand the idea that they’re never completely correct; searching for those errors is necessary. “This retraction illustrates how scientists and journals can work together to correct errors in science,” Carlisle adds.

Where the Mediterranean Diet Stands Overall After the Study Retraction

正如凯茨指出的那样，因为结果几乎相同，饮食本身真的不有问题。更重要的是，医学界围绕这种饮食风格健康益处的知识并不基于这项研究。“里昂饮食心脏研究早些时候显示了同性，”凯茨说，参考a study published inCirculation. “Two of the world’s five blue zone populations have Mediterranean diets. Conclusions in science are virtually never based on one study. We have many studies and many populations showing the health benefits of a Mediterranean diet.”

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Another example:a study published in July 2016 in theEuropean Heart Journalthat looked at 15,000 people with heart disease from 39 countries found that those who followed the Mediterranean diet more closely were less likely to experience a subsequent stroke, heart attack, or death related to heart disease compared with those who followed it less closely. For comparison, the Standard American Diet — which is rich in animal fat, soft drinks, chips, cookies, and cake — may be responsible for nearly half of all deaths from stroke, heart disease, and type 2 diabetes, suggestsa March 2017 study inJAMA.

Now that you know the Mediterranean diet’s reputation as one of the healthiest plans to follow, you can feel confident sitting down to a hearty plate of garlicky greens and beans drizzled in olive oil. Though, as Katz points out in hisown research review, there is no “最好的饮食” that everyone should follow. What matters most: “minimally加工食品靠近自然，主要是植物。“