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 adequately fortify the mother’s milk to meet the requirement of the breast fed infant and were not intended for longterm supplementation beyond the period of lactation.