The Med diet, rich in olive oil, fruit and vegetables and fish, has long been linked to lower incidence of heart disease, obesity and certain types of cancers. However, studies into the severity and prognosis of people with heart disease is lacking.

“The results of our study extend previous scientific knowledge that greater adherence to the Mediterranean diet has a beneficial effect on the severity of acute coronary syndrome (ACS), and on its short-term prognosis, in a free-eating population,” wrote Panagiotakos.

The new article, published on-line in the journal Nutrition (doi:10.1016/j.nut.2006.04.005), reports the results of the Greek Study of Acute Coronary Syndrome (GREECS) of 2172 patients (76 per cent men) who had been hospitalised with myocardial infarction (MI) or unstable angina (UA) and their adherence to the Mediterranean diet.

Dietary assessment was performed using validated, semi-quantitative 156-item food frequency questionnaires, and correlated to the Mediterranean diet using a 55-point scale. The higher the score, the closer to the Med diet.

Diet score was also linked to biological markers of heart disease and heart attack, such as cardiac troponin I, creatine phosphokinase, and creatine phosphokinase-MB, and an inverse association was observed.

Lower adherence to the Mediterranean diet, linked to younger patients, smokers, or people with a family history of coronary heart disease (CHD), was associated with a higher degree of severity of CHD.

“A five-unit increase in diet score [increased adherence to the Med diet] was associated with 15 per cent lower odds of having MI, after controlling for confounders,” said Panagiotakos.

The mechanism by which the Mediterranean diet exerts its benefits to heart health is thought to be complex, and scientists have proposed improvements in blood pressure, body weight, blood lipid concentrations, and inflammation.

“These mechanism might have a major impact on plaque instability, rupture, or erosion and the exacerbation of the following acute MI,” said the researchers.

The main limitations with this study are, firstly, that the study was limited to survivors of coronary events, and not people who died as a result of their first events. Secondly, people may have changed dietary habits leading up to or as a result of their CHD.

Despite these limitations, Panagiotakos and colleagues conclude: “At a population level, a Mediterranean dietary pattern with a potential of favourably modifying both the severity and the prognosis of ACS could be invaluable.”

Heart disease causes almost 50 per cent of deaths in Europe, and is reported to cost the EU economy an estimated €169 billion (£116 billion) per year.