Most breastfed infants are able to synthesize additional vitamin D through routine sunlight exposure. However, published reports of cases of vitamin D deficiency rickets among breastfed infants in the Unitied States caused researchers to take another look at whether all breastfed infants were getting adequate vitamin D.

Vitamin D deficiency rickets among breastfed infants is rare, but it can occur if an infant does not receive additional vitamin D from a vitamin supplement or from adequate exposure to sunlight. A number of factors decrease the amount of vitamin D a person will synthesize from sunlight. These factors include

·         Living at high latitudes (closer to the polar regions), particularly during winter months

·         Air quality conditions: high levels of air pollution

·         Weather conditions: dense cloud covering

·         The degree to which clothing covers the skin

·         Use of sunscreen

·         Skin pigmentation: darker skin types

Furthermore, there exists a major public health effort to decrease the risk of skin cancer by encouraging people to limit their sunlight exposure .

As a result, in April 2003, the American Academy of Pediatrics (AAP) published guidelines for vitamin D intake, recommending that all infants have a minimum intake of 200 IU of vitamin D per day, beginning during the first 2 months of life. In November 2008, the AAP published a new statement to replace their 2003 guidelines. The 2008 report recommends a daily intake of vitamin D of 400 IU/day for all infants and children beginning in the first few days of life.

Human milk typically contains a vitamin D concentration of 25 IU per liter or less. Therefore, a supplement of 400 IU per day of vitamin D is recommended for all breastfed infants. Adequate amounts of vitamin D can be achieved by currently available multivitamin products containing 400 IU of vitamin D per mL or the newly available preparations that contain 400 IU/mL vitamin D alone without other vitamins. These products are available over the counter. Prescription preparations of vitamin D have very high vitamin D concentration and are not for routine home use.

If an infant is weaned to vitamin-D fortified infant formula (consuming at least 1000 mL per day) or a child one year of age or older is weaned to vitamin-D fortified milk, then further supplementation is not necessary.