Primary Prevention of Cardiovascular Disease With a Mediterranean Diet

Study Questions:

What is the impact of compliance with a Mediterranean diet and primary prevention of cardiovascular events (CVEs) in persons at high risk?


PREDIMED, a multicenter trial, was conducted in Spain that randomly assigned participants who were at high CV risk (diabetes or at least three other risk factors), but with no CV disease at enrollment, to one of three diets: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to reduce dietary fat). Participants received quarterly individual and group educational sessions and, depending on group assignment, free provision of extra-virgin olive oil, mixed nuts, or small nonfood gifts. The primary endpoint was the rate of major CVEs (myocardial infarction, stroke, or death from CV causes). On the basis of the results of an interim analysis, the trial was stopped after a median follow-up of 4.8 years.


A total of 7,447 persons were enrolled (age range, 55-80 years); 57% were women. About 50% were obese, 80% had hypertension, 50% were diabetics, and 40% were taking statins. The two Mediterranean diet groups had good adherence to the intervention, according to self-reported intake and biomarker analyses. A primary endpoint event occurred in 288 participants. The multivariable-adjusted hazard ratios were 0.70 (95% confidence interval [CI], 0.54-0.92) and 0.72 (95% CI, 0.54-0.96) for the group assigned to a Mediterranean diet with extra-virgin olive oil (96 events) and the group assigned to a Mediterranean diet with nuts (83 events), respectively, versus the control group (109 events). No diet-related adverse effects were reported.


The authors concluded that among persons at high CV risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major CVEs.


The findings are consistent with many observational trials and randomized trials in coronary artery disease. Among the many plausible explanations for the value of the Mediterranean diet include increased sources of antioxidants; anti-inflammatory effects; low glycemic index; increase in alcohol; high consumption of fish, nuts, and olive oil; and less meat and meat products. The benefit of the diet was most robust in reduction of strokes, and persons with hypertension, obesity, and dyslipidemia. The Mediterranean diet impact was comparable to other evidence-based treatments, and possibly enhanced by discouraging low-fat diet participants from vegetable oils, nuts, and fatty fish.

Keywords: Reactive Oxygen Species, Coronary Artery Disease, Myocardial Infarction, Stroke, Follow-Up Studies, Risk Factors, Glycemic Index, Primary Prevention, Incidence, Dyslipidemias, Biomarkers, Spain, Cardiovascular Diseases, Obesity, Diet, Confidence Intervals, Hypertension, Thiazolidinediones, Diabetes Mellitus, Patient Compliance

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