COMMENTARY

Mediterranean Diet's Benefits May Extend to Multiple Diseases

William F. Balistreri, MD

Disclosures

November 07, 2018

In This Article

Protection Against CVD 

Heart disease and stroke are largely preventable; however, despite significant improvement in outcomes, they remain leading causes of morbidity, mortality, and healthcare costs in the United States.[8]

Million Hearts 2022, a collaboration among federal, state, and nongovernmental partners, fosters the implementation of evidence-based public health and clinical strategies aimed at keeping adults healthy to prevent cardiovascular events.[8] Diet and exercise are key components. In addition, in 2017, an American Heart Association advisory group stated that replacing saturated fat with polyunsaturated vegetable oil reduces the incidence of CVD by approximately 30%.[9] Replacing a processed food-heavy Westernized diet with the Mediterranean diet allows a shift from saturated to unsaturated fats.[9]

Adherence to a Mediterranean diet has been shown in both observational and randomized controlled trial data to improve surrogate markers of CVD, such as waist-to-hip ratio, lipids, and markers of inflammation, as well as primary CVD outcomes, such as death.[10,11]

The Mediterranean diet's purported long-term beneficial effects for the primary prevention of CVD have been extensively explored in a series of publications emerging from PREDIMED (PREvención con DIeta MEDiterránea), a multicenter, randomized, primary prevention trial.[12,13,14,15,16] In this trial, 7447 participants at high risk for CVD, but with no history of heart disease at enrollment, were assigned to one of three diets: a Mediterranean diet supplemented with extra-virgin olive oil (EVOO), a Mediterranean diet supplemented with mixed nuts, or a control (reduced fat) diet.[12,13] There were no energy restrictions and no specific recommendations for physical activity.

After a median follow-up of 4.8 years, the trial was stopped on the basis of a prespecified interim analysis. A primary clinical endpoint event (myocardial infarction, stroke, or CVD death) occurred in 288 participants. In the intention-to-treat analysis including all the participants, high-risk persons assigned to an energy-unrestricted Mediterranean diet supplemented with EVOO or nuts had a lower rate of major CVD events than those assigned to a reduced-fat diet. The investigators also noted significant improvements in classical and emerging risk factors for CVD, with a favorable effect of both Mediterranean diets on blood pressure, insulin sensitivity, lipid profiles, inflammation, oxidative stress, and carotid atherosclerosis.[13]

In addition, after 1-year follow-up, participants in the Mediterranean diet plus nuts intervention showed a significant (14%) reduction in the prevalence of metabolic syndrome compared with reductions of 7% and 2% in the Mediterranean diet plus EVOO and control groups, respectively.[14]

Guasch-Ferré and colleagues[15] assessed the association between total olive oil intake, its varieties (extra virgin and common olive oil), and the risk for CVD and mortality in the Mediterranean population participating in PREDIMED. Higher baseline total olive oil consumption was associated with a 48% reduced risk for CVD mortality. For each 10- g/day increase in EVOO consumption, CVD and mortality risk decreased by 10% and 7%, respectively.

Furthermore, a post hoc analysis of the PREDIMED trial suggested that EVOO in the context of a Mediterranean dietary pattern may reduce the risk for atrial fibrillation.[16]

Shikany and colleagues[17] also investigated the association of dietary patterns with recurrent acute CVD events and all-cause mortality in 3562 participants with existing heart disease. Over approximately 7 years of follow-up, there were 581 recurrent events and 1098 deaths. In multivariable-adjusted models, greater adherence to the Mediterranean diet was associated with both a lower hazard of recurrent CVD events and all-cause mortality.

The most recent confirmatory evidence of the association between adherence to a Mediterranean diet and CVD, a study by Alvarez-Alvarez and colleagues,[18] reported that the combined effects of baseline adherence to the diet and the practice of an active lifestyle and physical activity resulted in a 75% lower incidence of CVD.[18]

Thus, the PREDIMED trial and other studies provided strong evidence that a vegetable-based Mediterranean diet rich in unsaturated fat and polyphenols can be a practical and sustainable model for the prevention of CVD.

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