The Mediterranean diet's ascent to the top of nutritional science's evidence hierarchy had been building for decades by 2011, resting on a foundation of epidemiological data from southern European populations and increasingly supported by controlled intervention trials that were rare in nutrition research.

The core elements of the dietary pattern associated with longevity and reduced chronic disease in Greek and broader Mediterranean populations were fairly consistent across studies: high intake of olive oil as the primary fat source; abundant vegetables, fruits, legumes, and whole grains; regular fish consumption; moderate amounts of poultry and dairy; limited red meat; and moderate red wine consumption for those who drank alcohol.

What distinguished the Mediterranean diet from most nutrition fads was the quality and durability of its evidence base. The Seven Countries Study, begun by Ancel Keys in the 1950s, had tracked populations across multiple countries and found striking differences in cardiovascular outcomes that correlated with dietary patterns. Subsequent research refined and complicated the original findings but consistently supported the broad Mediterranean pattern.

The PREDIMED trial, whose major results would be published in 2013, would provide some of the strongest controlled evidence to that point: high-risk patients randomized to a Mediterranean diet supplemented with extra-virgin olive oil or nuts showed significantly reduced rates of major cardiovascular events compared to a low-fat control diet.

The appeal of the Mediterranean diet beyond its evidence base was also real: it involved eating real food, in reasonable quantities, prepared in ways that were genuinely pleasurable. As dietary interventions go, this was a remarkable advantage over most alternatives.