How the Mediterranean diet became so popular worldwide
The lands surrounding the Mediterranean Sea have been the scene of many cultures and civilizations and the Mediterranean diet is one of their most important achievements. Agriculture began with the cultivation of cereals and legumes in a region that nowadays includes the eastern Mediterranean countries (Lebanon, Israel, Palestine, Syria, Jordan and Iraq). Later, the Phoenicians, the Greeks and the Romans began to cultivate the three basic elements of the Mediterranean diet: olive trees for the production of olives and their oil, wheat for the preparation of bread, and grapevines, for the production of grapes and its main fermentation product: the wine.
A wide range of vegetable products was already consumed in Roman times, including onions, leeks, cabbage, lettuce, carrots, turnips, asparagus, celery and artichokes as well as numerous fruit varieties, including figs, apples, pears, cherries, plums, peaches, apricots and citrus fruits. Chestnuts, walnuts and almonds, represent other products commonly consumed in those times.
An important development of the Mediterranean diet occurred when, in the eighth century after Christ, the Moors occupied the Spanish peninsula. These populations introduced rice, lemons, eggplants, saffron and other spices: all products that gradually spread to the entire Mediterranean basin. The occupation of the Moors ended in 1492, the same year that Christopher Columbus arrived in the New World, returning to Spain with tomatoes and peppers, which are now an integral part of the Mediterranean diet.
However, the Mediterranean diet does not really exist. The Mediterranean Sea borders 18 countries that differ markedly in geography, economic status, health, lifestyle and, markedly, in their cuisine and diets.
The research about the Mediterranean diet
Why then has this concept become so popular and mainstream? Ancel Keys and his Italian colleague Flaminio Fidanza together with their colleagues involved in the 7 country study were central to the modern recognition, definition, and promotion of the eating pattern found in Italy and Greece in the 1950s and ’60s, and which is now popularly called “The Mediterranean Diet”. The Seven Countries Study included four cohorts from South Europe: Crete and Corfu in Greece, Dalmatia in Croatia and Montegiorgio in Italy.
In the 1960s the Greek diet had the highest content of olive oil and was high in fruit, the Dalmatian diet was highest in fish and the Italian diet was high in vegetables. Notably, these cohorts were characterized by low mortality rates from coronary heart disease. Therefore, the traditional diet characterizing these geographic areas has been postulated as one of the explanations of this lower incidence of disease. This type of diet had olive oil as its principal component of fat, it was high in unrefined cereal products, legumes, fruit and vegetables, moderate in fish and low in dairy and meat products. Finally, moderate amounts of wine were taken with meals.
After the seven-country study, many other researchers have followed the same stream and investigated the health effect of a dietary pattern in line with the major characteristics of the traditional diets observed in Greece, southern Italy and Dalmatia.
In particular, the Lyon Diet Heart Study was the first clinical trial to attempt to demonstrate the beneficial effects of the Mediterranean diet in reducing heart disease. Other trials include the Medi-RIVAGE study, the DIRECT study, the studies by Esposito and his colleagues in Italy and finally, the Spanish intervention study PREDIMED.
Notably, in 1995 the Greek epidemiologist Dimitrios Trichopoulou, developed the Mediterranean Diet Score, which has been modified several times and applied to a large number of observational studies as a practical tool to measure adherence to a Mediterranean-like pattern. The score, that I also used in some of my publications, gives an increasing number of points for high intakes of vegetables, fruit, nuts and seeds, legumes, fish and unsaturated fats as well as for low intakes of meat and dairy products. What is considered a high or low intake is different in each study where the score is calculated, since it’s based on the population medians or, in some studies, on the highest or lowest intake tertile.
Although the term “Mediterranean diet” is probably not completely appropriate, since it can fit other traditional diets such as the Nordic healthy diet and others, a diet that favours vegetable products and fish over other animal food products, is considered today one of the most effective dietary patterns in terms of cardiovascular prevention. A potentially broader definition of the Mediterranean diet should include fermented dairy products and cheese as well, which are traditional foods in south Europe, although the debate about their health properties is still ongoing.
Finally, inspired by the studies on the Mediterranean diet, several researchers from North Europe have tried to apply the same concepts and identified a Nordic healthy diet, sometimes defined as Baltic diet, for which a scoring system has been developed, similarly to what has been done for the Mediterranean diet.
