Serum Vitamin A in Relation to Genomic Biomarkers in Children: A Prospective Study

Background/Objectives: Vitamin A (VA), which is fat-soluble, belongs to the group of carotenoids, a class of highly effective antioxidant and genoprotective compounds (including astaxanthine, zeaxanthine, luteine). It plays a critical role in cellular growth, differentiation, and oxidative stress regulation, but prospective evidence linking childhood VA to subsequent genomic stability is scarce. This study investigated whether baseline VA levels were associated with later measurements of relative telomere length (RTL), four ribosomal DNA copy numbers (rDNA-CN: 5S, 18S, 28S, and 45S), and mitochondrial DNA copy number (mtDNA-CN) in children over a 4-year follow-up. Methods: Baseline VA levels were measured in 2021. In 2025, peripheral blood genomic DNA was extracted, and RTL, rDNA-CNs, and mtDNA-CN were quantified using qPCR. Multivariable linear regression and restricted cubic spline regression (RCS) were employed to examine the associations and dose–response shapes. Sex-stratified analyses with interaction tests were performed to evaluate effect modification by sex. Results: Among 215 children, baseline VA was positively associated with RTL, 5S rDNA-CN, 18S rDNA-CN, and 45S rDNA-CN after covariate adjustment. RCS analyses revealed strictly monotonic positive dose–response curves between VA and RTL, 5S rDNA-CN, and 18S rDNA-CN, with no statistically significant sex interaction (all p for interaction > 0.05). Conclusions: Higher childhood VA levels are positively associated with longer telomeres and higher rDNA-CN in later childhood, suggesting that adequate early-life VA may confer long-term benefits for ribosomal genomic stability and cellular aging. These observations expand our understanding of nutrition-related modulators of child genomic homeostasis and support further investigation into nutritional interventions targeting genomic protection in early life.