Final answer:
The American Academy of Pediatrics advises that infants receive 400 units of vitamin D supplement daily until their diet provides an adequate amount. This is needed to ensure infants have enough vitamin D for proper growth and bone health, as breast milk and limited sun exposure might not suffice.
Step-by-step explanation:
The American Academy of Pediatrics recommends that all infants, including those who are exclusively breastfed, should be given 400 units (IU) of supplemental vitamin D per day until intake from food sources reaches this amount. This is vital since breast milk typically does not provide sufficient vitamin D, and infants may not be exposed to adequate levels of sunlight to produce their own vitamin D effectively. The daily requirement of vitamin D is especially important for infants to ensure they have proper development and healthy bone growth.
While it is true that some foods like fatty fish and fortified milk or cereal contain vitamin D, and that our skin can synthesize vitamin D3 when exposed to sunlight, infants may still require supplementation. This is even more crucial for those living in northern latitudes or for infants with darker complexions, who are at a higher risk of vitamin D deficiency due to lesser efficiency in vitamin D synthesis from sunlight. A healthy baby may require a significant daily intake of milk, but this alone may not meet the recommended dietary allowances (RDA) of vitamin D, hence supplementation is suggested to prevent deficiencies.