AbstractBackgroundThe purpose of this study was to evaluate the association between vitamin B12 levels and Helicobacter Pylori infection and to examine the clinical usefulness of holotranscobalamin (holoTC) measurement in children.Materials and MethodsThirty patients between 6 and 15 years of age, who were diagnosed as H. pylori infected by C14 urea breath test, and 26 controls were enrolled in the study. Tests for complete blood count, serum vitamin B12 and folate, plasma total homocysteine, and holoTC levels were performed in each patient in the study and control groups.ResultsMean plasma holoTC concentrations were significantly lower in children with H. pylori infection before treatment (median 23.7 pmol/L (12.9–37.1 pmol/L)) versus after treatment (median 38.2 pmol/L (21.2–61.4 pmol/L)) and controls (median 36.1 pmol/L (12.6–58.7 pmol/L)).ConclusionsThe findings of our study suggest that H. pylori infection has a reversible negative effect on vitamin B12 status reflected in a decreased level of plasma holoTC that normalizes upon treatment of the infection, while no change is observed in total plasma vitamin B12.