The American Academy of Pediatrics (AAP) has doubled the amount of vitamin D recommended for infants, children and adolescents, from 200 IU to 400 IU starting in the first few days of life. The previous recommendation, issued in 2003, was amended following a review of new clinical trials on vitamin D and evidence suggesting the safety of giving 400 IU per day to the pediatric population. Clinical data indicate that 400 IU of vitamin D a day will prevent and treat rickets, a bone-weakening disease. Adequate vitamin D throughout childhood may also reduce the risk of osteoporosis.