For years, the Mediterranean diet has ruled as the undisputed top dog for weight loss. (Here’s how eating like a Greek god can help you lose weight.) And honestly, what’s not to love? A diet rich in plant-based foods like vegetables, nuts, fruits, and whole grains—plus less red meat and butter—can do wonders for your waistline and your heart. Plentiful doses of omega-3s, soluble and insoluble fibers, and micronutrients keeps your body burning fat all day long.
But like most diets, there’s more to this heart-healthy trend than meets the eye. Researchers just discovered that the Mediterranean diet only works for some people and not for others.
Their study, published in the International Journal of Epidemiology, analyzed 18,000 randomly selected residents of southern Italy between 2005 and 2010. After controlling for health and socioeconomic variables such as BMI, education, and household income, the research team scored participants’ meals using the Mediterranean Diet Score. Not only did this metric account for the variety of fruits, veggies, meat, and fish consumed, but it also evaluated the participants’ cooking methods. Healthy methods such as boiling and stewing received higher scores, while unhealthy methods such as frying, roasting, or grilling earned less points.
Naturally, the data showed that the Mediterranean diet effectively reduced cardiovascular disease risk. Yet that result only applied to a select group of participants: those with higher income or more education.
“We found heart advantages were limited to high socioeconomic status groups, even if groups showed the same adherence to the Mediterranean diet,” Marialaura Bonaccio, lead author of the new study and a researcher at IRCCS Istituto Neurologico Mediterraneo Neuromed, an Italian Clinical Research Institute, said. Meanwhile, the participants in the low income and low education bracket did not experience any benefits.
The research team noted that participants in the most advantaged category tended to have a higher quality diet, consuming more fish, organic products, and whole grain foods than their lower income counterparts. Bonaccio also speculated that those with higher incomes are more inclined to pay for more expensive food, preferring a $10 bottle of olive oil over a $3 bottle. That, too, could account for the health discrepancy. (Here’s how to make your own diet more Mediterranean.)
While this is great news for those with better education and incomes, more work still needs to be done to ensure a quality diet for all. Making healthy foods affordable and accessible can improve health around the world—no matter the education or income level.
“A good diet is undoubtedly more than just a shopping list,” Dr. Barbara Berkeley, who practices medicine with a specialization in weight management in Beachwood, Ohio, told CNN. “Quality, freshness, variety and purity of production may truly differentiate diets even when they appear to be the same.”