The Mediterranean diet really is that good for you. Here’s why

In the 1950s, researchers from across the globe embarked on a sweeping and ambitious study. For decades, they scrutinized the diets and lifestyles of thousands of middle-aged men living in the United States, Europe and Japan and then examined how those characteristics affected their risks of developing cardiovascular disease.

The Seven Countries Study, as it later became known, famously found associations between saturated fats, cholesterol levels and coronary heart disease. But the researchers also reported another notable result: Those who lived in and around the Mediterranean — in countries like Italy, Greece and Croatia — had lower rates of cardiovascular disease than participants who lived elsewhere. Their diets, rich in fruits, vegetables, legumes, whole grains, nuts, seeds, lean proteins and healthy fats, seemed to have a protective effect.

Since then, the...