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A new study highlights how income factors into the diet's effectiveness.

August 01, 2017

The Mediterranean diet is one of the most touted diets out there, allegedly helping protect us from Alzheimer's, breast cancer, and osteoporosis, and even making up for eating junk food. Unlike trendier diets like Atkins or Paleo, the Mediterranean plan feels a bit more down-to-earth, offering a somewhat less strict approach to choosing what you eat, and has consistently been shown to benefit heart health. But a new study suggests that the Mediterranean diet may come with an odd quirk: Its cardiovascular benefits are only experienced by richer or more educated people. Apparently, besides switching from butter to olive oil, you also need to switch to a better paying job.

The study, published this week in the International Journal of Epidemiology, looked at over 18,000 people living in Molise in southern Italy between March 2005 and April 2010. Researchers tracked a number of health and personal factors, as well as participants’ adherence to the diet, a so-called “Mediterranean Diet Score.” Following up an average of four years later, the study found the diet did reduce the risk of cardiovascular disease, but only for some people, specifically those with a household income of over $45,000 or a post-secondary education. “We found heart advantages were limited to high socioeconomic status groups, even if groups showed the same adherence to the Mediterranean diet,” said lead author Marialaura Bonaccio of Italy’s IRCCS Istituto Neurologico Mediterraneo Neuromed where the study was conducted.

The resulting big question, obviously, is why this occurs. Bonaccio suggests it’s a “focus on quantity, rather than quality.” “Let’s give that two persons follow the same diet, that is equal amounts of vegetables, fruits, fish, olive oil etc. every day so that they report the same adherence score to Mediterranean diet,” she said. “It might be that, beyond quantity, differences in quality may exist. For example, in olive oil.” She says those with better means are more likely to spend more money on higher quality olive oil and other ingredients. “Our hypothesis is that differences in the price may yield differences in healthy components and future health outcomes,” she continued.

Giovanni de Gaetano, director of the Department of Epidemiology and Prevention at the IRCCS Neuromed, pointed out that these findings create an ethical issue. “During the very last years, we documented a rapid shifting from the Mediterranean diet in the whole population, but it might also be that the weakest citizens tend to buy 'Mediterranean' food with lower nutritional value,” he said. “We cannot be keeping on say that the Mediterranean diet is good for health … if we are not able to guarantee an equal access to it.”