Redox–Metabolic Crosstalk in Pediatric MASLD: Biomarkers, Mechanisms, and the Emerging Role of Selenium

Childhood obesity is an important global health issue closely related to metabolic syndrome and metabolic dysfunction-associated fatty liver disease (MASLD), currently the most common chronic liver disease in children. Oxidative stress and insulin resistance are the driving forces in hepatocyte injury and disease progression. There is growing interest in new biomarkers for detecting and monitoring metabolic and hepatic changes. We aimed to synthesize current evidence regarding biomarkers of oxidative stress and MASLD, and the potential modulatory role of selenium in pediatric populations. A literature search of PubMed, Scopus, Web of Science, and the Cochrane Library identified studies in children and adolescents (0–18 years) published between January 2000 and December 2025. Associative diagnostic biomarkers included indicators of oxidative damage, antioxidant-defense markers, and integrated oxidative stress indices, which appear promising but lack pediatric reference ranges, while prognostic biomarkers capture the inflammatory consequences of redox imbalance but with limited liver specificity. Metabolomics profiling and multiomics approaches remain experimental. Selenium, an essential trace element with antioxidant properties, plays a role in maintaining redox balance through selenoproteins, but pediatric evidence is limited and at times contradictory. Few biomarkers are clinically ready. Further longitudinal studies in pediatric populations are needed to better clarify the role of selenium, as well as to support the development of age-appropriate diagnostic strategies utilizing multiomics for MASLD, empowering clinicians to implement timely interventions in childhood obesity.