Seven RCTs were included in the review (3,650 patients). All trials had an open design. Allocation concealment was adequate in five trials. Blinding assessment for all outcomes was adequate in two trials. Follow-up ranged from two to four years (where reported). Most trials had rates of loss to follow up less than 10%. No trial was stopped early for benefit.
Compared with low-fat diets, Mediterranean diets were associated with a significant reduction in body weight (WMD -2.24kg, 95% CI -3.85 to -0.63; six RCTs), body mass index (WMD -0.56 kg/m2, 95% CI -1.01 to -0.11; six RCTs), systolic blood pressure (WMD -1.70mmHg, 95% CI -3.35 to -0.05; six RCTs), diastolic blood pressure (WMD -1.47mmHg, 95% CI -2.14 to -0.81; six RCTs), and total cholesterol (WMD -7.35mg/dL, 95% CI-10.32 to -4.39; six RCTs) at two years follow-up. Substantial heterogeneity was observed for these outcomes (Ι² ranged from 60% to 97%).
Sensitivity analyses did not materially alter the results. There was no evidence of publication bias.