Dear Doctor: Apparently one size does not fit all when it comes to the Mediterranean diet, because a recent study found that rich people benefit from it and poor people don't. It can't be as simple as that. What gives?
Dear Reader: We confess that after reading several of the news reports generated by the release of this study, we were tempted to write our own headlines. The gist would be: "Let's Ignore Significant Details So We Can Come to Flawed But Provocative Conclusions!"
It's true that the researchers did find a link between income and the health outcomes of the subjects of their study who followed the Mediterranean diet. Specifically, individuals with more money reaped measurable health benefits, and those who had less money did not. But as you suggest, the how and why of these results is more nuanced than simply rich versus poor.
Whether it set out to or not, this study adds to a body of research that examines how economics and education affect our health. People with lower income levels not only have less money to spend on food, but they also have fewer options when it comes to shopping. It's an important topic that the National Institutes of Health classifies as environmental justice. But let's pull back a bit and get to the details of the study at hand.
First, the Mediterranean diet. It cuts out refined and processed foods, unhealthy fats and limits sugar. Instead, the emphasis is on a variety of fresh fruits and vegetables, leafy greens, nuts, legumes, unrefined grains and cereals, olive oil, and modest consumption of fish, lean meat and dairy products. Past studies have tied the diet to improved cardiovascular health, lower cancer risk and increased longevity. So when researchers in Italy analyzed four years of self-reported dietary data from 19,000 women and men, they weren't surprised that those who followed the Mediterranean diet had a lower incidence of heart problems.
But there was a catch. After the participants were further sorted according to levels of income and education, the benefits of the diet were not universal. People with lower income levels didn't show a reduction in cardiovascular risk. Digging deeper, the researchers learned that while everyone in the study adhered to the basic principles of the Mediterranean diet, when it came to the specific foods being eaten, marked differences emerged. That's where education -- yet another interesting twist -- comes in.
According to the study, participants with more education ate the widest range of fruits and vegetables. Individuals with higher income levels ate the most nuts, whole grains, fresh fruits and fish. The diets of those on the lower end of the education and income scale included more meat, less fish, less variety in fruit and vegetable choices, and cooking methods that were less healthful.
The authors acknowledge the pitfalls of drawing conclusions from studies with self-reported data. At the very least, when it comes to the health outcomes of the Mediterranean diet, we've learned that details matter. And in the bigger picture, the differences in income and education meant everyone in the study wasn't on the same diet after all.
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