A Science News piece on the massive study on the Mediterranean diet published in the NEJM.
A total of 7,447 people following major cardiovascular risk factors participated in the study. They were divided into three dietary intervention groups: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with nuts (walnuts, almonds, hazelnuts), and a low-fat diet (animal and vegetable). A dietician visited the patients every three months and they attended dietary training group sessions, in which they received detailed information about the Mediterranean and the low-fat diet, and the food included in each one. Moreover, they were provided with shopping lists, menus and recipes adapted to each type of diet and each season of the year.
During the study, those participants who followed any of the two types of Mediterranean diet received freely extra-virgin olive oil (one litre per week), and nuts (30 grams per day; 15 grams of walnuts, 7.5 grams of almonds and 7.5 grams of hazelnuts).
After five years, it has been proved that participants who followed any of the two types of Mediterranean diet showed a substantial reduction in the risk of suffering a cardiovascular death, a myocardial infarction or a stroke.
According to the researchers, the results of PREDIMED study are relevant as they prove that a high-vegetable fat diet is healthier at a cardiovascular level than a low-fat diet. The authors state that the study has been controversial as it provides new data to reject the idea that it is necessary to reduce fats in order to improve cardiovascular health.
A very large amount of olive oil - very little animal based fats, very little meat other than certain types of fish three times a week, almost no refined sugars or grains, a lot of fruits and vegetables, lots of tree nuts, and a moderate amount of alcohol and dark chocolate. Exactly which part of of the diet works and how it might be optimized are unclear, but are grounds for further studies.
So expect sales of olive oil and nuts to take off - they are the easy parts to add.
The NEJM paper is outside their firewall.
Primary Prevention of Cardiovascular Disease with a Mediterranean Diet
Ramón Estruch, M.D., Ph.D., Emilio Ros, M.D., Ph.D., Jordi Salas-Salvadó, M.D., Ph.D., Maria-Isabel Covas, D.Pharm., Ph.D., Dolores Corella, D.Pharm., Ph.D., Fernando Arós, M.D., Ph.D., Enrique Gómez-Gracia, M.D., Ph.D., Valentina Ruiz-Gutiérrez, Ph.D., Miquel Fiol, M.D., Ph.D., José Lapetra, M.D., Ph.D., Rosa Maria Lamuela-Raventos, D.Pharm., Ph.D., Lluís Serra-Majem, M.D., Ph.D., Xavier Pintó, M.D., Ph.D., Josep Basora, M.D., Ph.D., Miguel Angel Muñoz, M.D., Ph.D., José V. Sorlí, M.D., Ph.D., José Alfredo Martínez, D.Pharm, M.D., Ph.D., and Miguel Angel Martínez-González, M.D., Ph.D. for the PREDIMED Study Investigators
February 25, 2013DOI: 10.1056/NEJMoa1200303
The NY Times on what the diet is... It is probably important to note the subjects did not gain or lose weight, so that risk factor did not come into play.
There has been quite a bit of work noting the relative health of people who follow this diet, but this is the first major study that looked outside that gene pool. There is also weaker evidence (Loma Linda studies) that a vegan Mediterranean diet may be at least this healthy. That one is associated with lower body weights and a very low incidence of late life medical conditions. Many new studies are called for, although this type of work is slow in producing results and it is difficult to recruit subjects (changing your diet for long periods of time is extremely non-trivial and researchers would need thousands of subjects). In the meantime there are some definite guides with this one.