Effectiveness comparison of different school-based nutrition education interventions to improve fruit and vegetable (F&V) consumption in schoolchildren not yet well researched. We evaluated the effectiveness of two school-based interventions promoting fruit and vegetable intake among Italian schoolchildren. In this randomized intervention trials, the first intervention was conducted by schoolteachers who attended a nutritionist-led training course (group-1), the second intervention conducted by schoolteachers who performed a self-training course (group-2). Thirty-two second to fifth-grade elementary classes enrolling 96 schoolteachers and 813 schoolchildren were randomized, and assigned to the two different nutrition education interventions. 804 students completed the study. By the end of the study, the group-1 (n = 409) followed by the teachers who attended a nutritionist-led course successfully increased the consumption of fruit and vegetables: in 183 (44.7%) and 157 (38.3%) schoolchildren respectively; the group-2 (n = 395) with teachers who performed a self-training course reported an increased consumption of fruit and vegetables in 81 (20.5%) and 76 (19.2%), respectively. This study indicates that a school-based nutrition education conducted by teachers who attended a nutritionist-led training course has a significant impact on primary school-age children's F&V intake.