Piecemeal evidence over the last three decades has shown that a diet rich in grains, fruit, vegetables and olive oil but stingy on meat and dairy -- washed down with a modest daily dose of wine -- promotes health.
But a meta-study published in the British Medical Journal is the first to sift through all this data in an attempt to quantify the overall benefits.
'Our findings support a simple recommendation: eat in a more Mediterranean way because it reduces the incidence of chronic disease,' the lead researcher, Francesco Sofi of the University of Florence, told AFP by phone.
Pouring over a dozen scientific surveys conducted since 1966 and involving more than 1.5 million people, Sofi and a team of researchers in Italy created a scale of one to nine corresponding to different food groups.
Someone who consumed all the healthiest foodstuffs and largely avoided the harmful ones -- a theoretically-perfect Mediterranean diet -- would score a perfect nine, he explained.
The study found that a bump of two points anywhere in the scale -- moving, say, from zero to two, or from six to eight -- corresponded to a 'significant reduction in overall mortality,' Sofi said.
When broken down by disease, such a shift in dietary habits lowered the risk of death from cardiovascular disease by nine percent and from cancer by six percent.
The study also evaluated a recent set of findings on the impact of diet on neurodegenerative disease, and concluded that going Mediterranean decreased the incidence of Alzheimer's and Parkinson's by 13 percent.
These results are 'clinically relevant for public health,' and suggest that getting one's daily calorie intake from these food groups could play an important role in preventing major chronic diseases, Sofi said.
Despite growing evidence of its benefits, some specialists up to now have been reluctant to fully endorse the Mediterranean way.
'We need more studies to find out whether the diet itself or other lifestyle factors account for the lower deaths from heart disease,' the American Heart Association says on its website.
Ironically, most of the more than dozen countries ringing the Mediterranean Sea are slowly abandoning their traditional foods in favor of more meat, saturated fats and processed foods, according to the UN's Food and Agriculture Organization (FAO).
'The European diet has become too fat, too salty and too sweet,' Josef Schmidhuber, an economist at the FAO, said earlier this month in a statement. The traditional balance of foods found in southern Europe and Northern Africa 'is declining into a moribund state,' he said.
Historically, more than half the fat calories in a Mediterranean diet come from monounsaturated fats -- mainly olive oil -- that do not raise blood cholesterol levels the way saturated fats do.
Sofi hopes that his scoring system might help people improve their eating habits.
'Adherence to the score could be a good way to measure the quality of a diet,' she said.
He is currently doing more research on what the optimum quantity of each food group would be for a balanced diet.
'Then we would be in a position to recommend eating a specific amount of, say, fish or fruits,' he said.