Age-specific association between dietary nutrient adequacy and self-rated health in Korean adolescents: a cross-sectional study based on the Korea National Health and Nutrition Examination Survey 2022–2024

Background Self-rated health (SRH) reliably predicts mortality and chronic disease risk, yet the association between the mean adequacy ratio (MAR), a nutrient adequacy index, and SRH in Korean adolescents remains underexplored. Methods This cross-sectional study analyzed 1,053 adolescents aged 12–18 years from Korea National Health and Nutrition Examination Survey (KNHANES) 2022–2024, excluding those with extreme energy intakes for their sex and age group. MAR was calculated as the mean of nine nutrient adequacy ratios, each capped at 1.0 using the 2020 Korean Dietary Reference Intakes (KDRI). The dietary diversity score (DDS) was calculated from five food groups. SRH was dichotomized as good (1–2) or fair-to-poor (3–5), and associations were estimated using complex-sample logistic regression with a quasibinomial family. Results In the fully adjusted model, higher MAR was associated with lower odds of fair-to-poor SRH (OR: 0.88, 95% CI: 0.78–0.99; p = 0.040). In exploratory analyses, this association was observed in adolescents aged 15–18 years (OR: 0.79, 95% CI: 0.68–0.93; p = 0.005) but not 12–14 years (OR: 1.02, 95% CI: 0.85–1.22; p = 0.851; age group interaction p = 0.017). DDS showed no association with fair-to-poor SRH (OR: 1.00, 95% CI: 0.83–1.21; p = 0.960). MAR was not associated with overweight (OR: 1.06, 95% CI: 0.91–1.23; p = 0.477) or abdominal obesity (OR: 1.03, 95% CI: 0.88–1.20; p = 0.737). A sensitivity analysis using the 2025 KDRI yielded consistent results: the primary association remained significant (OR: 0.87, 95% CI: 0.78–0.98; p = 0.027), and the age group interaction remained statistically significant ( p = 0.013). Conclusion Higher MAR was associated with lower odds of fair-to-poor SRH in Korean adolescents, particularly among those aged 15–18 years. Longitudinal studies are needed to confirm these findings and support nutrition programs targeting older Korean adolescents.