Vitamin B12: As Important to Pediatricians as to Geriatricians

Vitamin B12 deficiency during infancy is not unusual in newly industrialized and developing countries however reports of vitamin B12 deficiency during infancy are uncommon in the industrialized areas of Western and Northern Europe, North America, Australia and New Zealand, and the majority of reported cases are in exclusively breastfed infants of mothers consuming vegetarian or vegan diets. Neonatal vitamin B12 status at birth is determined by mother’s vitamin B12 status during pregnancy and vitamin B12 concentrations in breast milk are highly correlated with maternal vitamin B12 levels. Due to rapid brain and somatic growth, infant vitamin B12 stores can be quickly depleted if there is insufficient vitamin B12 in the breast milk. The most commonly described symptoms of deficiency during infancy are irritability, apathy, hypotonia, growth failure, refusal to wean from the breast or to eat complementary foods and developmental regression. Recent literature suggests vitamin B12 deficiency in breast-fed infants is much more common than previously recognized and given vitamin B12 plays an important role in the synthesis and methylation of DNA, the methylation of histones and other regulators of gene expression, and mitochondrial metabolism, even modest deficiency may be associated with subtle neurologic abnormalities and developmental delays.