The Mediterranean diet only works if you live in household earning £35,000 and are highly educated, a new study suggests.
Although health experts advocate a diet rich in fresh fruit, vegetables, olive oil, fish and nuts, researchers now believe that the quality of food is crucial for seeing the benefits.
Italian researchers studied the impact of a Mediterranean diet on reducing heart disease risk in 18,000 men and women over a four-year period.
In line with similar research they discovered that sticking to the plan reduced the risk of heart disease by 15 per cent, but only for people with a household income of £35,000 or higher. No actual benefits were observed for the less advantaged groups.
The researchers said the finding was surprising, and have speculated that more affluent families are able to buy better quality food which is higher in antioxidants, polyphenols and lower in pesticides.
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“The cardiovascular benefits associated with the Mediterranean diet in a general population are well known, yet for the first time our study has revealed that the socioeconomic position is able to modulate the health advantages linked to Mediterranean diet,” said Dr Marialaura Bonaccio, a researcher at the Department of Epidemiology and Prevention at the Neurological Mediterranean Institute (Neuromed).
“In other words, a person from low socioeconomic status is unlikely to get the same advantages of a person with higher income, despite the fact that they both similarly adhere to the same healthy diet.
“These substantial differences in consuming products belonging to Mediterranean diet lead us to think that quality of foods may be as important for health as quantity and frequency of intake”.
Dr Giovanni de Gaetano, director of the Department at Neuromed, said the public health message that the Mediterranean diet is beneficial for everyone may need to change.
“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”.
However, British experts said that other factors could behind the difference in outcomes for the richest and poorest people.
Dr Tim Chico, Reader in Cardiovascular Medicine, University of Sheffield, said: “This study confirms a well-known but depressing fact; people of lower education or income have almost double the risk of heart disease compared with those who are better off.
“Although the authors of this study suggest that the Mediterranean diet may be less effective in reducing heart disease in less well-off people, this is likely to be due to other differences between low and high income groups, rather than the diet not being effective.
“These findings should not put anyone off a Mediterranean diet; this is still the best option for reducing risk of heart disease.”
The research was published in the International Journal of Epidemiology.