LAUSR

Key Points Question Does a dosage of 1000 IU per day compared with 400 IU per day of supplemental vitamin D in infants born with serum 25-hydroxyvitamin D concentrations less than 50 nmol/L (ie, 20 ng/mL) present advantages to bone outcomes throughout infancy? Findings In this prespecified secondary analysis of a double-blinded randomized clinical trial including 139 healthy term infants, whole-body bone mineral content, lumbar spine bone mineral content and density, and bone biomarkers were not different among dosage groups from age 1 to 12 months. Meaning This study supports a standard daily supplemental dose of 400 IU of vitamin D in breastfed infants in Montreal, even if born with serum 25-hydroxyvitamin D concentrations less than 50 nmol/L.