Hilda Bastian at PLOS Blogs wrote about the recent retraction of a PREDIMED sub-study published in the New England Journal of Medicine in 2013. The suspect conclusion of that study was: “Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.”
From Ms Bastian:
A very influential nutrition trial just tanked. It was retracted from the New England Journal of Medicine (NEJM) on 13 June, and re-published with new analyses and toned-down conclusions. Both Gina Kolata, writing in the New York Times, and Alison McCook, writing at NPR, imply, at least to some extent, that it might make no difference to the evidence. But I disagree.
Here’s what’s happened to the trial, and where I think it leaves the overall evidence. Called PREDIMED, it was a multi-center trial from Spain, with the NEJM final report published in 2013. Altogether, 7,447 people at risk of cardiovascular disease (CVD) – heart attack and stroke – were reported as randomized to one of 3 groups:
- Mediterranean diet with free olive oil provided, along with individual and group training sessions at the start, and then quarterly;
- Mediterranean diet with free nuts provided, along with individual and group training sessions at the start, and then quarterly;
- Advice to reduce fat intake, with a leaflet – but after the first 3 years, people in this control group were also offered individual and group training sessions.
The primary endpoint for the trial was a composite one of major cardiovascular events: myocardial infarction, stroke, or CVD-related death. And the trial was stopped early. More people dropped out of the control group than the Mediterranean diet groups.There are several alarm bells here already, and we’ll come back to those.
I encourage you to read Ms Bastian’s article if you enjoy such debates. I consider the 2013 PREDIMED sub-study to be one of numerous pieces of the nutritional puzzle.
I published the 2nd edition of my Advanced Mediterranean Diet in 2012, so the 2013 PREDIMED sub-study was not available to me. At the end of my book you’ll find not one, but 43 scientific references supporting the healthfulness of the Mediterranean diet.
My Conquer Diabetes and Prediabetes book was also based predominantly on those 43 studies.
Steve Parker, M.D.