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AJM online Letter| Volume 129, ISSUE 1, e11, January 2016

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Cardiovascular Benefits of the Mediterranean Diet Are Driven by Stroke Reduction and Possibly by Decreased Atrial Fibrillation Incidence

      To the Editor:
      Widmer et al assemble a wealth of information on “The Mediterranean Diet, its Components, and Cardiovascular Disease,”
      • Widmer R.J.
      • Flammer A.J.
      • Lerman L.O.
      • Lerman A.
      The Mediterranean diet, its components, and cardiovascular disease.
      a topic that is of ever-growing importance. They are right to call the Prevención con Dieta Mediterránea (PREDIMED) trial
      • Estruch R.
      • Ros E.
      • Salas-Salvado J.
      • et al.
      Primary prevention of cardiovascular disease with a Mediterranean diet.
      a “flagship study,” or, as I might paraphrase, a landmark study that changes clinical practice in terms of what diet we might recommend to our patients. PREDIMED was a well-designed randomized controlled trial with a significant sample size.
      However, I believe that the benefits of this study are somewhat mischaracterized. The primary endpoint was a composite of myocardial infarction, stroke, or cardiovascular death. The statistically significant difference of this composite endpoint (adjusted hazard ratios: 0.70; 95% confidence interval [CI], 0.54-0.92 and 0.72; 95% CI, 0.54-0.96 for diets rich in extra virgin olive oil and nuts, respectively, compared with a low-fat diet) was driven by a reduction in strokes. Except for stroke, all other endpoints were not significantly different between the Mediterranean diets and the control diet. Interestingly, the PREDIMED investigators published a post hoc analysis
      • Martínez-González MÁ
      • Toledo E.
      • Arós F.
      • et al.
      Extravirgin olive oil consumption reduces risk of atrial fibrillation: the PREDIMED (Prevención con Dieta Mediterránea) trial.
      in which they found that both Mediterranean diets reduced the risk of new-onset atrial fibrillation by 38% in an age- and sex-adjusted model for the extra virgin olive oil-containing diet compared with the low-fat diet (95% CI, 0.46-0.88) after a median follow-up of 4.7 years. Unfortunately, we do not know the distribution of the stroke etiologies in PREDIMED. If decreased atrial fibrillation contributes to the lower stroke rate seen in this trial and whether the mechanism is better-controlled blood pressure, decreased platelet activation, increased plasma antioxidant capacity, improved endothelial function and regeneration, reduced systemic inflammation, preservation of telomere length,
      • Crous-Bou M.
      • Fung T.T.
      • Prescott J.
      • et al.
      Mediterranean diet and telomere length in Nurses' Health Study: population based cohort study.
      or a combination thereof, remains to be seen.

      References

        • Widmer R.J.
        • Flammer A.J.
        • Lerman L.O.
        • Lerman A.
        The Mediterranean diet, its components, and cardiovascular disease.
        Am J Med. 2015; 128: 229-238
        • Estruch R.
        • Ros E.
        • Salas-Salvado J.
        • et al.
        Primary prevention of cardiovascular disease with a Mediterranean diet.
        N Engl J Med. 2013; 368: 1279-1290
        • Martínez-González MÁ
        • Toledo E.
        • Arós F.
        • et al.
        Extravirgin olive oil consumption reduces risk of atrial fibrillation: the PREDIMED (Prevención con Dieta Mediterránea) trial.
        Circulation. 2014; 130: 18-26
        • Crous-Bou M.
        • Fung T.T.
        • Prescott J.
        • et al.
        Mediterranean diet and telomere length in Nurses' Health Study: population based cohort study.
        BMJ. 2014; 349: g6674

      Linked Article

      • The Mediterranean Diet, its Components, and Cardiovascular Disease
        The American Journal of MedicineVol. 128Issue 3
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          One of the best-studied diets for cardiovascular health is the Mediterranean diet. This consists of fish, monounsaturated fats from olive oil, fruits, vegetables, whole grains, legumes/nuts, and moderate alcohol consumption. The Mediterranean diet has been shown to reduce the burden, or even prevent the development, of cardiovascular disease, breast cancer, depression, colorectal cancer, diabetes, obesity, asthma, erectile dysfunction, and cognitive decline. This diet is also known to improve surrogates of cardiovascular disease, such as waist-to-hip ratio, lipids, and markers of inflammation, as well as primary cardiovascular disease outcomes such as death and events in both observational and randomized controlled trial data.
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