In 2011, the IOM updated vitaminD supplementation guidelines.A dequate intake for infants younger than1year was set at 400 IU/d, in linewith the AAP recommendations and the goals of supplementation.The recommended dietary allowance for adults, including lactating mothers,was listed at 600IU/d.The doses of vitaminD used in this study were selected to a dequately fortify th emother’s milk to meet the requirement of the breast fed infant and were not intended for longterm supplementation beyond the period of lactation.