A 2008 American Academy of Pediatrics (AAP) clinical report recommends that all breastfed and partially breastfed infants should be supplemented with 400 IU a day of vitamin D, beginning in the first few days of life to prevent rickets, a condition that continues to be reported in US infants. All non-breastfed infants, as well as older children, who are consuming less than one quart per day of vitamin D-fortified formula or milk, should also receive a vitamin D supplement of 400 IU a day. This new recommendation is not because breast milk itself is deficient in vitamin D but instead because, as doctors, we recommend that children be relatively sunlight deficient to prevent skin damage and skin cancers later in life. And since children are sunlight-deficient, we need to supplement them with vitamin D.