Last week, news broke that one of the leading medical journals, the New England Journal of Medicine (NEJM), had to print a retraction.
Now, you've likely seen retractions in regular media channels. As we learn more or clarify facts, we have to update stories. Or sometimes an error slips past even the best proofreaders.
But rarely do we see scientific paper retractions in medical journals. The rate is roughly one out of every 1,000 papers, with biological and medical papers having the highest numbers.
Each time a major journal prints a retraction, it spurs questions of credibility. Unfortunately, many major news outlets fail to explain just why it happened or what it means for the conclusions involved.
That's why when we saw the headlines about our favorite diet, we had to dive into the reasoning. The paper that was pulled from and then reprinted in the NEJM was about the heart benefits of the Mediterranean diet.
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Today we want to explain what really happened, why it's a good thing, and why the diet is still just as great as we thought.
It started with an anesthesiologist. John Carlisle wrote into a journal about how so many articles about anesthesia contained too many errors. The journal wrote back: Prove it. So Carlisle set out to do just that. He devised what's now called the Carlisle method to detect errors in randomization.
Randomized clinical trials, as we've written before, are the gold standard for evidence-based medicine. They involve taking participants and separating them into groups using a randomization program. But sometimes humans don't make it perfectly random. Often, couples participating might receive the same treatment or an entire group in a hospital might get the same treatment. It's far from the ideal.
That's what happened in the Mediterranean diet study. About 14% of the participants did not receive a random assignment.
Here's the thing... The researchers re-ran the data and excluded the groups who weren't properly randomized. They still saw that some people following a Mediterranean diet had fewer heart attacks, strokes, and deaths from heart disease. It worked best for those with a high risk of heart disease.
The researchers say that the study can't apply to those at low risk anymore due to the error. However, there's plenty of evidence that the components of the diet are great for heart health. That includes olive oil, fish, and plenty of fresh fruits and vegetables.
For instance, we know that olive oil contains significant amounts of antioxidants and monounsaturated fatty acids (or "MUFAs"). MUFAs keep insulin levels in check, making olive oil good for diabetics. They also help with cholesterol levels.
Moreover, due to its chemical structure and function, olive oil also protects your cells from oxidation damage. Thus, olive oil reduces risk of developing diseases of inflammation. That includes heart disease, arthritis, and high blood pressure.
Fish also contain these MUFAs. Fish also have polyunsaturated fats, which include the omega fatty acids. These acids reduce inflammation and promote brain health. They also keep your bones healthy and your metabolism on track.
And since fish oil pills may contain higher levels of toxins, I try to eat fish instead. I prefer to eat fish that are lower in mercury... like salmon, light tuna, herring, mackerel, and anchovies.
Finally, I always recommend fruits and vegetables for a healthy diet. About 10 servings a day is ideal for lowering your risk of cancer and premature death. Even just two and a half servings provide some benefit, but the more the better.
We've also seen how the Mediterranean diet also protects against cognitive decline. What's more, a study in monkeys showed that following the diet improved good gut bacteria. Remember, our guts contain trillions of bacteria that regulate everything from digestion to our immune system.
And finally, a brand-new Greek study out this month also found adherence to the Mediterranean diet reduced the number of cardiac events for 10 years.
Retractions are still relatively rare compared with the growth of published papers each year. And in the high-impact journals like NEJM, more readers mean more chances of finding errors. That's why retractions keep research transparent. So don't let the headlines throw you. The Mediterranean diet is still good for our health and it's easy to add these foods to your diet today.
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Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
June 19, 2018