Sticking to the Mediterranean diet will keep your heart healthy but only if you're wealthy or highly educated, according to a new analysis from Italian researchers. Though some experts question the nuance of those findings.
For years, scientists have been evaluating the benefits of the Mediterranean diet, characterized by consuming lots of fruits, vegetables, legumes, whole grains, and some seafood or chicken, with moderate amounts of dairy and little red meat or sweets. (The exact quantities of these foods has been the subject of debate). Studies have suggested that people who adhere to a Mediterranean diet have a lower risk of cancer and neurodegenerative diseases such as Alzheimer's, and are more likely to live longer. So it looks like the Mediterranean diet is pretty healthy all around. But there's a lingering question: Does everyone benefit equally?
In the study, published Monday in the International Journal of Epidemiology, the researchers analyzed data compiled from more than 24,000 Italians over the age of 35. Through a series of questionnaires and self-reports, the researchers analyzed how strictly participants followed the Mediterranean diet and their socioeconomic class, correlating it with incidences of cardiovascular disease (heart attack, bypass surgeries, high blood pressure) collected from hospital records and death certificates. After weeding out participants with incomplete data or concurrent health conditions that might throw off the analysis, the researchers reviewed data from more than 13,000 people.
They found that the people who adhered most strictly to the Mediterranean diet had fewer incidences of heart disease—that part wasn't new. But for rich and poor people who were equally good at sticking to the diet, only the rich people reaped the benefits of it: people in the highest socioeconomic bracket and education level had a 57 percent lower risk of developing heart disease, while people with lower incomes and with lower education levels had the same risk as if they weren't following the diet at all.
This study, like many others, suggests that eating like you live along the Mediterranean can benefit your health. "Yet again we have confirmation that the Mediterranean diet is associated with better cardiovascular outcomes...that's important. It's the kind of concept that merits reinforcement," says Clyde Yancy, chief of medicine and cardiology at the Northwestern University Feinberg School of Medicine and a spokesperson for the American Heart Association.
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But beyond that top-level message, we have to look pretty carefully at what else the paper says. The data was collected in Italy, where the average person eats a bit differently than your average American, so the results might not be applicable to an American population, says Alice Lichtenstein, a Gershoff Professor of nutrition science and policy at Tufts University. People are also notoriously awful at remembering what they eat (seriously, what did you have for dinner on Friday?), which could have thrown off the results, though that's not the researchers' fault.
And there was something funny about the data, Lichtenstein notes. Education level is usually a stand-in for socioeconomic class—the two correlate pretty closely, she says, at least in the US. But in this study, people with more education ate a greater diversity of fruits and vegetables, while those with high income had less diversity than their lower-income counterparts. "You'd probably think people with a higher education level would be more likely to be aware of what healthier dietary patterns are and to adhere to them. But if you look at the data, when [the researchers] separate out education versus income, it's not clear that's actually happening," Lichtenstein says.
That's not a reason to disqualify the findings completely, but it's enough that you should probably be a bit skeptical. "We're starting with a small denominator of available subjects to study. When we divide them into different groups, we start to see signals that don't line up with logic," Yancy says.
The researchers explain the disparity in health outcomes by the fact that wealthier people have more options for what to eat. Lichtenstein thinks that probably plays a part, though having time to prepare food, less stress about putting food on the table, and living near places to buy good and nutritious food are likely factors as well.
To Yancy, it comes down to access. "Is it true that the Mediterranean diet doesn't work in those who are less advantaged? Or that it works across the board, but those with fewer resources can't access all the components in the diet?" he says.
The researchers' findings, in short, underline the health disparities between socioeconomic groups that researchers and public health officials already know about. There are some federal programs in place to educate low-income people in the US about nutrition and healthy food behavior, most notably with SNAP (Supplemental Nutrition Assistance Program, formerly known as food stamps), and they can be effective.
But in order to close the health disparity gap, low-income groups need access to better nutrition, which could help alleviate a number of the health problems that plague these communities, such as obesity, diabetes, and heart disease. And that means policy changes.
"One of the challenges we face is how to make healthier foods available to more people, irrespective of income," Yancy says, especially given the relationship between nutrition and disease. "These data allow us to double down on the importance of improving access to fresh fruits and vegetables across the board."
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