Effect of a collaborative learning–based nutrition education intervention on diet quality and nutrition knowledge among in-school adolescents in Ogun State, Nigeria: a quasi-experimental study

Background Poor diet quality and inadequate nutrition knowledge during adolescence contribute to micronutrient deficiencies and increasing non-communicable disease (NCD) risk in low- and middle-income countries. Evidence remains limited on whether collaborative learning–based nutrition education improves objectively measured diet quality among adolescents in sub-Saharan Africa. This study evaluated the effect of a collaborative learning–based nutrition education intervention on diet quality and nutrition knowledge among in-school adolescents in Ogun State, Nigeria. Methods A quasi-experimental pretest–posttest control group design was employed among 274 adolescents aged 13–19 years enrolled in private secondary schools. Participants were assigned to either a collaborative learning–based nutrition education intervention or usual didactic instruction over eight weeks. Diet quality was assessed using the Diet Quality Questionnaire (DQQ), generating Dietary Diversity Score (DDS), NCD-Protect, NCD-Risk, and Global Dietary Recommendations (GDR) scores. Nutrition knowledge was assessed using a validated questionnaire. Within- and between-group changes were analyzed using paired and independent tests, and analysis of covariance (ANCOVA) adjusted for baseline values and sociodemographic factors. Results Compared with controls, the intervention group showed significantly greater improvements in NCD-Protect score (Δ = 3.03; p  < 0.001), NCD-Risk score (Δ=−1.11; p  < 0.001), and GDR score (Δ = 4.14; p  < 0.001). Improvements in DDS were observed in both groups, with no significant between-group difference. Nutrition knowledge increased significantly in the intervention group (Δ = 9.39; p  < 0.001). ANCOVA confirmed a strong independent intervention effect on GDR (ηp²=0.26) and nutrition knowledge (ηp²=0.13). Conclusion Collaborative learning–based nutrition education significantly improves diet quality and nutrition knowledge among adolescents and represents a promising school-based strategy for NCD prevention in settings undergoing dietary transition.