Eligibility criteria

We included RCTs with follow-up periods of three months or more, examining the effects of a Mediterranean-style diet in adults (18 years or more) without established CVD and in those with established CVD to determine the effects of the intervention on primary and secondary prevention respectively. To reach our definition of a Mediterranean-style diet the intervention needed to include at least the following two components: a high monounsaturated/saturated fat ratio (use of olive oil as main cooking ingredient and/or consumption of other traditional foods high in monounsaturated fats such as tree nuts); and high intake of plant-based foods, including fruits, vegetables and legumes. This definition was based on recent work showing that the protective effects of the diet appear to be most attributable to olive oil, fruits, vegetables and legumes [5,30]. We considered trials where the comparison group was no intervention or minimal intervention (e.g. leaflet to follow a dietary pattern with no person-to-person intervention or reinforcement) and also other dietary interventions. Outcomes included CVD clinical endpoints and CVD risk factors (lipid levels, blood pressure).