Open Access Highly Accessed Research article

Effect of the Mediterranean diet on blood pressure in the PREDIMED trial: results from a randomized controlled trial

Estefania Toledo123, Frank B Hu24, Ramon Estruch35, Pilar Buil-Cosiales13, Dolores Corella36, Jordi Salas-Salvadó37, M Isabel Covas38, Fernando Arós39, Enrique Gómez-Gracia103, Miquel Fiol113, Jose Lapetra123, Luis Serra-Majem133, Xavier Pinto143, Rosa M Lamuela-Raventós153, Guillermo Saez16173, Mònica Bulló37, Valentina Ruiz-Gutiérrez183, Emilio Ros193, José V Sorli2036 and Miguel Angel Martinez-Gonzalez13*

Author Affiliations

1 Department of Preventive Medicine and Public Health, University of Navarra, Pamplona, Navarra, Spain

2 Department of Nutrition, Harvard School of Public Health, Boston, MA, USA

3 CIBER Fisiopatología de la Obesidad y Nutrición (CIBER OBN), Instituto de Salud Carlos III (ISCIII), Spanish Government, Madrid, Spain

4 Harvard Medical School and Channing Lab, Brigham Women’s Hospital, Boston, MA, USA

5 Department of Internal Medicine, Institut d’Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), Hospital Clinic, University of Barcelona, Barcelona, Spain

6 Department of Preventive Medicine and Public Health, University of Valencia, Valencia, Spain

7 Human Nutrition Department, IISPV, Universitat Rovira i Virgili, Reus, Spain

8 Cardiovascular and Nutrition Research Group, Institut de Recerca Hospital del Mar, Barcelona, Spain

9 Department of Cardiology, University Hospital of Alava, Vitoria, Spain

10 Department of Preventive Medicine, University of Malaga, Malaga, Spain

11 Institute of Health Sciences IUNICS, University of the Balearic Islands, and Hospital Son Espases, Palma de Mallorca, Spain

12 Department of Family Medicine, Primary Care Division of Sevilla, San Pablo Health Center, Sevilla, Spain

13 Department of Clinical Sciences, University of Las Palmas de Gran Canaria, Las Palmas, Spain

14 Lipids and Vascular Risk Unit, Internal Medicine, Hospital Universitario de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain

15 Department of Nutrition and Food Science, School of Pharmacy, XaRTA, INSA, University of Barcelona, Barcelona, Spain

16 Department of Biochemistry and Molecular Biology, School of Medicine, University of Valencia, Valencia, Spain

17 Department of Clinical Analyses, University Hospital of Valencia, Valencia, Spain

18 Instituto de la Grasa, Consejo Superior de Investigaciones Cientificas, Sevilla, Spain

19 Lipid Clinic, Department of Endocrinology and Nutrition, Institut d’Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), Hospital Clinic, University of Barcelona, Barcelona, Spain

20 Primary Care Division, Valencia Institute of Health, Valencia, Spain

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BMC Medicine 2013, 11:207  doi:10.1186/1741-7015-11-207

Published: 19 September 2013



Hypertension can be prevented by adopting healthy dietary patterns. Our aim was to assess the 4-year effect on blood pressure (BP) control of a randomized feeding trial promoting the traditional Mediterranean dietary pattern.


The PREDIMED primary prevention trial is a randomized, single-blinded, controlled trial conducted in Spanish primary healthcare centers. We recruited 7,447 men (aged 55 to 80 years) and women (aged 60 to 80 years) who had high risk for cardiovascular disease. Participants were assigned to a control group or to one of two Mediterranean diets. The control group received education on following a low-fat diet, while the groups on Mediterranean diets received nutritional education and also free foods; either extra virgin olive oil, or nuts. Trained personnel measured participants’ BP at baseline and once yearly during a 4-year follow-up. We used generalized estimating equations to assess the differences between groups during the follow-up.


The percentage of participants with controlled BP increased in all three intervention groups (P-value for within-group changes: P<0.001). Participants allocated to either of the two Mediterranean diet groups had significantly lower diastolic BP than the participants in the control group (−1.53 mmHg (95% confidence interval (CI) −2.01 to −1.04) for the Mediterranean diet supplemented with extra virgin olive oil, and −0.65 mmHg (95% CI -1.15 to −0.15) mmHg for the Mediterranean diet supplemented with nuts). No between-group differences in changes of systolic BP were seen.


Both the traditional Mediterranean diet and a low-fat diet exerted beneficial effects on BP and could be part of advice to patients for controlling BP. However, we found lower values of diastolic BP in the two groups promoting the Mediterranean diet with extra virgin olive oil or with nuts than in the control group.

Trial registration

Current Controlled Trials ISRCTN35739639

Mediterranean diet; Low-fat diet; Systolic blood pressure; Diastolic blood pressure; Controlled trial; PREDIMED trial; Monounsaturated fat; Dietary patterns; Olive oil; Nuts