Transcription
So what's the truth about the Mediterranean diet? Is it really a health miracle or just more misguided diet hype?
Hi, I'm Howard Jacobson, contributing author to Whole: Rethinking the Science of Nutrition. The Mediterranean diet is nothing new. There's already a lot of cookbooks out about it, and it's clearly the diet to choose if you have 28 days to look amazing in a yellow bikini.
But recently, a study came out suggesting that the Mediterranean diet is the world's healthiest diet. Diet. It was published in the New England Journal of Medicine, and you've probably seen it because of articles like this in the New York Times: "Mediterranean Diet Shown to Ward Off Heart Attack and Stroke." About 30% of heart attack, strokes, and deaths from heart disease can be prevented, the author says. Fox News weighs in with an article by a doctor: "Protecting Your Heart with the Mediterranean Diet." Dallas News claims that the "Mediterranean Diet Study Rocks the Medical World," and NBC News says, "Tasty Diet Cuts Heart Disease, Study Finds."
So I was really curious. This sounds like great news. So what I thought I would do is take a look at the real study, the published study in the New England Journal of Medicine, and see what it says.
The study was conducted in Spain and assigned 15,000 people randomly to one of three groups: a Mediterranean diet plus extra virgin olive oil, a Mediterranean diet plus tree nuts, or what they called the low-fat diet, or the control diet. I'll frame my discussion of the results with two big problems.
The first problem is, it turns out that all three diets are killers. Here's the actual data as reported in the New England Journal of Medicine. The top row, the total number of events, is simply adding up the next three rows: the number of strokes, heart attacks, and deaths from cardiovascular causes. They added another column, death from any cause, at the bottom. Now, to be more accurate, we're going to use not the actual numbers, but the rates of events per thousand people per year.
So the first thing to notice here is that the only outcome in which the Mediterranean diet outperformed the control diet was the number of strokes. In fact, this data shows that the number of heart attacks is statistically the same, the number of deaths from cardiovascular causes is statistically the same, and the number of deaths from any cause is statistically the same. The only reason that the overall rate is statistically significant is because of the rate of strokes.
So that's one thing. The second thing is that the rate of strokes and the rate of all these events is incredibly high in the Mediterranean diets, both with olive oil and with nuts. Human beings are not built for cardiovascular disease. Cardiovascular disease is not something that naturally happens to us and we try to prevent with diet. Cardiovascular disease is something that only happens with a diet that causes cardiovascular disease. So the fact that these numbers are so high is the real story, not that they're so low.
So the second problem is that the diets weren't really different. So again, let's return to the actual data reported in the New England Journal of Medicine and let's focus on the percentage of calories from fat in each diet. The extra virgin olive oil group averaged 41.2% of their calories from fat. The nuts group averaged slightly more, 41.5. And the control group averaged 37% of their calories from fat. That is called the low-fat diet, which begs the question, why on earth would they choose that diet as a low-fat diet?
And there's really only two possibilities. One is they felt that couldn't get people to have less fat than that. And again, this is a randomized trial, so people were just assigned to that group, so it would be very difficult to assign people to a truly healthy diet. The second, more sinister possibility, is that the researchers wanted a straw man. They wanted to have a what they called a low-fat diet, but actually wasn't, so that they could prove, supposedly, once and for all, that low-fat diets don't protect you from heart disease.
So just to give you a pictorial representation of the three diets, when we do a scale from 0 to 100, you can see the two Mediterranean diets are just over 40, and the low-fat diet, in quotes, is almost the same amount. Let's compare that to the standard American diet, which is actually lower in fat than the supposed low-fat diet. And just for the sake of sanity, the diet that we write about in Whole: Rethinking the Science of Nutrition, the Whole Foods Plant-Based diet, clocks in at 10% calories from fat. That's truly a low-fat, heart-healthy diet.
So perhaps the New York Times should run a correction in its next issue, changing the headline to "Three Almost Identically Bad Diets Produce Three Almost Identically Bad Health Outcomes."
I'm Howard Jacobson, contributing author to Whole: Rethinking the Science of Nutrition. It's available for pre-order now, or you can pick it up in your favorite bookstore in May. Until next time, be well, my friends.