Researchers put volunteers with both higher and lower incomes on a Mediterranean diet, but only the participants with higher incomes showed health benefits.

The Mediterranean diet, with its emphasis on olive oil, fish, and unrefined foods, has long been seen as a healthy way of lowering the risk of heart disease and leading a healthier life.

Researchers have shown that these health benefits are indeed real, but only for those who can pay.

A research team from the Italian Istituto Neurologico Mediterraneo Neuromed (Institute for Research, Hospitalization, and Health Care) studied more than 18,000 adherents to the Mediterranean diet. Their findings were recently published in the International Journal of Epidemiology.

They found that when people followed this eating pattern, cardiovascular risk factors were only lowered in those with higher educational levels and/or higher incomes.

In those who had received less education or made less money, researchers observed no benefits.

Researchers say their findings should spark a discussion on how people learn about and obtain their food.

Participants were asked to adhere to an optimal Mediterranean diet.

They were measured by a score indicating their intake of fruits and nuts, vegetables, legumes, cereals, fish, fats, meat, dairy products, and alcohol intake.

Participants following an optimal Mediterranean diet came from various walks of life. So why did their outcomes differ so much?

“Although we cannot definitely answer this question, we observed that, given a similar adherence to the Mediterranean diet, people with higher socioeconomic position (higher income, or greater educational level) showed more favorable eating behaviors overall,” Marialaura Bonaccio, PhD, researcher at the Department of Epidemiology and Prevention and first author of the study, explained in an email to Healthline.

Bonaccio said that those with more favorable health outcomes were more likely to report a diet rich in antioxidants or polyphenols, as well as whole-grain or organic foods and a variety of fruits and vegetables.

“Such disparities persist within a comparable Mediterranean diet adherence, and possibly account for the different health outcomes observed in the socioeconomic groups,” she said.

In other words, not all Mediterranean diets are created equal. The diet dictates what foods are eaten, but not the quality of these foods.

When asked what specific higher-quality foods might be inaccessible to those in a lower socioeconomic bracket, Bonaccio used olive oil as an example.

“Here in Italy, we have a wide range of products with different costs and different nutritional properties,” she said. “It is unlikely that a bottle of extra virgin olive oil that costs two or three euros has the same nutritional properties of a bottle that costs around 10 euros. Our hypothesis is that differences in the price may yield differences in healthy components and future health outcomes. Of course, those with higher incomes are more likely to buy the 10-euro bottle than subjects with low incomes, and this is a reasonable explanation of the fact that such disparities in access to food would provide different heart benefits over time.”

The research team plans to expand on their findings by getting more precise information on exactly where people are getting their food, as well as the ways that one’s socioeconomic standing impacts their access to high-quality food.

Beyond this, Bonaccio said, there are two areas in which to take action.

“The first should aim to improve nutrition knowledge of less educated people by, for instance, giving more correct information on diet and its relationship with health, starting early in life (primary school),” she wrote. “For example, everyone is likely aware that eating fruits and vegetables is good for health, but few may know that variety in such foods may be as important as quantity.”

The second step could be getting governments to invest in good health.

“People should be put in the condition of adopting a healthy diet,” said Bonaccio. “In light of this, one could imagine that the expenses for high quality certified Mediterranean diet-related foods be at least partially deductible from state or regional taxes, or the related value-added tax (VAT) be selectively reduced.”

As an example, Bonaccio suggested that taxes on olive oil of unknown origin should be higher than the taxes on extra virgin olive oil of certified origin.

Giovanni de Gaetano, director of the Department of Epidemiology and Prevention, said that the findings should frame the Mediterranean diet in a new light — one that takes into account socioeconomic status.

“We cannot be keeping on saying that the Mediterranean diet is good for health if we are not able to guarantee equal access to it,” he said in a release.