Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts

Abstract

To the Editor: At the time of the publication of the first PREDIMED (Prevención con Dieta Mediterránea) trial results in 2013,¹ the relative reduction of 30% in the risk of cardiovascular events among participants assigned to a Mediterranean diet seemed to be an effect size that was “too good to be true” for a dietary pattern.² The trial results were recently retracted and republished (June 21 issue)³ after exclusion of study sites that violated randomization principles. However, the large effect size remained the same, as well as the existence of other sources of bias. First, imbalances in medical care may . . .