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Update on the Mediterranean Diet
How does the retraction and republication of the PREDIMED trial affect recommendations for a Mediterranean diet? The related PEN content was reviewed and updated accordingly:
The Mediterranean dietary pattern is recommended to lower the risk of cardiovascular disease (CVD).
Grade of Evidence B
A clinical trial from Spain (PREDIMED study) was retracted due to irregularities in the randomization procedures that included enrolling participants who were not randomized. In the PREDIMED trial, participants were randomized by advice to follow a Mediterranean (Med) diet supplemented with extra-virgin olive oil (50 g/4 Tbsp/day), a Med diet supplemented with nuts (30 g/day walnuts, hazelnuts and almonds) or a control, low fat diet. The study was reanalyzed by excluding participants (n=1588) who deviated from the randomization protocol; republished results did not change the overall results (1). After a follow up of five years, a 29-32% reduction in major CVD events (composite of myocardial infarction, stroke, or CVD mortality) was reported in both of the Mediterranean diet groups compared to the control. When the 1,588 participants were excluded from the analysis, the risk of major CVD events was: Med diet + olive oil group (hazard ratio (HR) 0.71; 95%CI, 0.52 to 0.97); Med diet + nuts (HR 0.68; 95% CI, 0.49 to 0.95). For individual components, only stroke risk was significantly reduced (Med diets combined HR, 0.58; 95%CI, 0.42 to 0.82). Effects on blood lipids were not reported.
For additional information, see the PEN Practice Question: In adults with elevated LDL-cholesterol (LDL-C), what are the effects of dietary patterns (i.e. Portfolio, Mediterranean, DASH) on LDL-C levels?
- Estruch R, Ros E, Salas-Salvadó J, Covas MI, Corella D, Arós F, et al.; PREDIMED Study Investigators. Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra-virgin olive oil or nuts. N Engl J Med. 2018 Jun 21;378(25):e34. doi: 10.1056/NEJMoa1800389. Epub 2018 Jun 13. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/29897866