Aims: To systematically synthesize evidence on the reported results of peer-based nutrition education interventions for dietary behaviors and selected psychosocial outcomes among adolescents aged 10-19 years, and to describe common characteristics and peer roles in interventions reporting favorable findings.

Methods: This systematic review was reported according to PRISMA 2020, with synthesis without meta-analysis reported using SWiM. PubMed/MEDLINE, ScienceDirect, Cochrane Library, Web of Science, PsycINFO, and Google Scholar were searched; the last search was conducted on 20 August 2026. The protocol was registered on OSF Registries on 23 September 2026 after completion of the final search; therefore, this was a retrospective, post-search registration rather than prospective registration. Two reviewers independently screened and extracted data. Risk of bias was assessed using RoB 2/the cluster-randomized RoB 2 variant and EPHPP. Certainty of evidence was evaluated using GRADE.

Results: Of 3,177 records, 842 duplicates were removed and 2,335 were screened. Full-text retrieval was sought for 155 reports; 10 were not retrieved, 145 were assessed, and 132 were excluded using one primary reason per report. Thirteen reports representing 11 original intervention studies were included. Two studies reported favorable findings for fruit intake and two for study-specific beverage outcomes: sugar-sweetened beverages in Nguyen et al. (2021) and carbonated-beverage intake in Singhal. Nguyen et al. (2021) reported an approximately +36 g/day between-group difference in fruit intake and −0.79 times/day for sugar-sweetened beverages; Singhal et al. reported a 15.1-percentage-point lower prevalence of carbonated-beverage intake (p<0.001); this study-specific outcome was not assumed to represent all sugar-sweetened beverages. Nutrition knowledge improved in three studies. GRADE certainty was low for nutrition knowledge, and very low for fruit intake, study-specific beverage outcomes, self-efficacy, and the remaining outcome domains.

Conclusions: Evidence for peer-based nutrition education showed heterogeneous findings across dietary and psychosocial outcomes. Favorable findings were reported for fruit intake, study-specific beverage outcomes, and nutrition knowledge, but certainty ranged from low to very low; self-efficacy findings were mixed. Future studies should use stronger designs, standardized outcome measurement, and longer follow-up; comparative designs are also needed to determine whether adding peer components to school or food-environment strategies provides additional benefit.