In 2003 Greek researcher Antonia Trichopoulou attempted to quantify the benefits of the Mediterranean diet.
Working on the hypothesis that older Greeks were more likely to have followed a typical Mediterranean diet for most of their lives, the researchers looked at the diets of 22,000 Greeks over the age of 65.
Trichopoulou developed a point score system, assigning subjects higher points for greater adherence to the diet. Unsurprisingly by this stage, those who followed the diet closely were found to have a lower mortality rate.
However, subsequent researchers found that when they applied the point system to northern Europeans there was no similar correlation with low mortality rates.
This was because the main source of monounsaturated fats in northern European diets was not olive oil, a key component of the Mediterranean diet and packed with polyphenols and antioxidants unique to olives.