Prevention and Treatment of Total CVD
In terms of heart health, the Mediterranean diet has been found to have an athero- protective role and to be associated with CVD risk reduction and the improvement of the attributing risk factors (Sofi et al. 2010, 2014). A recent meta-analysis of 14
prospective studies showed that a 2-point increase in the MDS (Trichopoulou et al. 2003) was associated with significantly higher protection against CVD and, in particular, with a 10% lower risk of CVD incidence and/or mortality (Sofi et al. 2014). This meta-analysis updated a previous one by the same group that had showed a similar result (RR 0.90; 95% CI 0.87-0.93) (Sofi et al. 2010). An even more recent meta-analysis of 20 prospective studies also revealed the inverse association of high Mediterranean diet adherence with a decreased risk of CVD incidence (fatal or nonfatal) (RR 0.71; 95% CI 0.65, 0.78) compared with the lowest adherence (Grosso et al. 2015).
Although dietary patterns receive increased attention compared with single nutrients or food groups, the lack of consistency in the methods used (e.g., variations in definitions, metrics, and statistical approaches) led the 2007 World Cancer Research Fund Report (World Cancer Research Fund and Research 2007) and the 2010 Dietary Guidelines Advisory Committee (USDA 2010) to decide, at the time, that firm conclusions regarding the association of dietary patterns and health outcomes could not be drawn due to insufficient evidence. Following these recommendations, the Dietary Patterns Methods Project (DPMP) was initiated in 2012 by the National Cancer Institute in an attempt to strengthen the already existing evidence (Reedy et al. 2014). The DPMP relates dietary patterns to mortality by conducting simultaneous analyses in three U.S. cohorts that all use identical methods and models (Liese et al. 2015). The assessment of the dietary patterns was performed through the systematic examination of four indices (the Healthy Eating Index 2010 [HEI- 2010] [Guenther et al. 2013], the Alternative Healthy Eating Index 2010 [AHEI-2010] [Chiuve et al. 2012a], the Alternate Mediterranean Diet [aMED] score [Fung et al. 2005], and the Dietary Approaches to Stop Hypertension [DASH] score [Fung et al. 2008]) and their associations with all-cause, CVD, and cancer mortality among older adults in the United States (Reedy et al. 2014). The sample consisted of adults between the ages of 50 and 71 that were followed from 1995 through to the end of 2011 (Reedy et al. 2014). During the 15 years of follow-up, 86,419 deaths were documented overall, of which 23,502 were CVD deaths (15,497 for men and 8,005 for women) (Reedy et al. 2014). The DPMP reported that aMED showed significant associations with CVD mortality.
Only a few RCTs have been carried out to assess the effect of the Mediterranean diet on total CVD. It is worth mentioning that the most important is the Prevention con Dieta Mediterranea (PREDIMED) study, a large RCT that assesses the impact of the Mediterranean diet on the primary prevention of CVD, within the frame of the Mediterranean diet (Estruch et al. 2013). The sample of the trial consisted of men and women who did not have CVD at baseline, but had either type 2 diabetes or at least three cardiovascular risk factors (current smoking, hypertension, high LDL or lipid-lowering therapy, low HDL, overweight/obesity, family history of premature CHD). Their results showed that adherence to the Mediterranean diet, with extra supplementation of either extra virgin olive oil (mean consumption at the end of the trial 50 g/day) or nuts (mean consumption at the end of the trial 30 g/day) and no energy restriction compared with a low-fat control diet, resulted in a significant risk reduction of total CVD—a composite of cardiovascular death, myocardial infarction, and stroke (HR 0.70, 95% CI 0.54-0.92 for the olive oil group and HR 0.72,
95% CI 0.54-0.96 for the nuts group) (Estruch et al. 2013). A meta-analysis of four RCTs, including the results of the PREDIMED study, showed that for a total of 12,293 individuals at high CVD risk and 590 composite cases of CVD, the pooled estimated risk of fatal and nonfatal CVD incidence was 0.55 (95% CI 0.39, 0.76) for the Mediterranean diet group compared with the control (Grosso et al. 2015). The interventions among the four studies differed regarding the focus on Mediterranean diet components, while participants in the control groups were given similar dietary advice (Grosso et al. 2015).
Very few studies have been realized for the assessment of the Mediterranean diet on CVD treatment (secondary prevention). Results from the Lyon Diet Heart Study, an RCT that investigated the effect of the Mediterranean diet on the recurrence rate after a first incident of myocardial infarction (de Lorgeril et al. 1999), confirmed its beneficial effects. The hazard ratios between the group of participants that followed the Mediterranean diet and the group of participants that did not receive any dietary recommendation ranged from 0.28 to 0.53 for the various end points (cardiac death and nonfatal myocardial infarction: HR 0.28, 95% CI 0.15-0.53; the preceding plus major secondary end points [unstable angina, stroke, heart failure, etc.]: HR 0.33, 95% CI 0.21-0.52; the preceding plus minor events requiring hospital admission: HR
0.53 95% CI 0.38-0.74) (de Lorgeril et al. 1999). It seems that even variations of the Mediterranean diet can have a beneficial secondary prevention effect as shown by an RCT that assessed the impact of an Indo-Mediterranean diet on total CVD mortality compared with the dietary pattern recommended by Step 1 of the National Cholesterol Education Program (NCEP1) and found that the risk of CVD incidence (fatal or nonfatal) was reduced for the Indo-Mediterranean diet group by 52% (Singh et al. 2002).