High adherence to the Mediterranean diet is associated with cardiovascular protection in higher but not in lower socioeconomic groups: prospective findings from the Moli-sani study

It is uncertain whether the cardiovascular benefits associated with Mediterranean diet (MD) may differ across socioeconomic groups. Prospective analysis on 18991 men and women aged ≥35 years from the general population of the Moli-sani cohort (Italy). Adherence to MD was appraised by the Mediterranean diet score (MDS). Household income (euros/year) and educational level were used as indicators of socioeconomic status. Hazard ratios (HR) were calculated by multivariable Cox proportional hazard models. Over 4.3 years of follow-up, 252 cardiovascular disease (CVD) events occurred. Overall, a two-point increase in MDS was associated with 15% reduced CVD risk (95% confidence interval: 1% to 27%). Such association was evident in highly (HR = 0.43; 0.25-0.72) but not in less (HR = 0.94; 0.78-1.14) educated subjects (P for interaction = 0.042). Similarly, CVD advantages associated with the MD were confined to the high household income group (HR = 0.39; 0.23-0.66, and HR = 1.01; 0.79-1.29 for high- and low-income groups, respectively; P for interaction = 0.0098). In a subgroup of individuals of different socioeconomic status but sharing similar MDS, diet-related disparities were found as different intakes of antioxidants and polyphenols, fatty acids, micronutrients, dietary antioxidant capacity, dietary diversity, organic vegetables and whole grain bread consumption. MD is associated with lower CVD risk but this relationship is confined to higher socioeconomic groups. In groups sharing similar scores of adherence to MD, diet-related disparities across socioeconomic groups persisted. These nutritional gaps may reasonably explain at least in part the socioeconomic pattern of CVD protection from the MD.