Determinants of stunting among Indonesian children: a cross-sectional study on the role of child, maternal, and vaccination factors.

Vitamin B12 (cobalamin) is a water-soluble vitamin which acts as a cofactor for methionine synthase and methylmalonyl-CoA mutase, enzymes involved in homocysteine remethylation and mitochondrial fatty acid metabolism (, ). Deficiency results in impaired DNA synthesis, ineffective erythropoiesis, accumulation of methylmalonic acid (MMA) and homocysteine, and progressive neurological dysfunction. The spectrum of Vitamin B12 deficiency ranges from asymptomatic biochemical deficiency to severe pancytopenia, developmental regression, seizures, movement disorders, and irreversible neurocognitive impairment (, ). Although megaloblastic anemia remains a classic presentation, many children may present with a normocytic anemia or isolated neurological symptoms. Delayed recognition continues to be a major challenge. Vitamin B12 deficiency is widely prevalent yet underrecognized nutritional disorder among Indian children. The Comprehensive National Nutrition Survey (CNNS) reported deficiency in 13.8% of preschool children, 17.3% of school-age children, and 31.0% of adolescents, indicating a substantial public health burden (). In hospital-based studies on patients attending a tertiary care center in New Delhi, vitamin B12 deficiency was seen in 37.6% of apparently healthy infants and toddlers, while Azad et al. reported deficiency in 22% of infants with an association with neurodevelopmental delay (, ).