Vitamin D: How much is enough?

Vitamin D is necessary for calcium absorption and utilization, and vitamin D deficiency can result in rickets in young children and increased fracture risk in older children and adolescents. It may also be important for cardiac and metabolic function, protection against certain types of infection, and prevention of some cancers, said Neville H. Golden, MD, chief, Division of Adolescent Medicine, and the Marron and Elizabeth Kendrick Professor in Pediatrics at Stanford University School of Medicine, California.

At a session on Saturday, October 11, titled “Vitamin D: bones and beyond-when to screen, whom to treat, and how to treat,” he noted that the recommended daily allowance for children aged older than 1 year is now 600 IU/d of vitamin D, which is higher than previous recommendations.

Vitamin D is produced in the skin after exposure to sunlight. Optimal exposure is between 10 am and 3 pm in the spring, summer, and fall. Children who spend most of their time indoors or who have their bodies covered by clothing when they are outdoors are at risk for vitamin D deficiency. Obese children and those with dark skin are at particular risk. Wearing sunscreen with an SPF greater than 8 prevents adequate production of vitamin D in the skin.

Good dietary sources of vitamin D include fatty fish as well as infant formula, milk, and other fortified foods and drinks. Breast milk does not have sufficient vitamin D. Breast-fed and partially breast-fed infants should be supplemented with 400 IU/d of vitamin D, starting in the first few days of life and continued until the infant has been weaned and is drinking at least 1 L/d of vitamin D-fortified infant formula or cow’s milk, Golden advised.

The AAP does not recommend universal screening for vitamin D deficiency but does support vitamin D screening in children and adolescents with conditions associated with reduced bone mass, such as diabetes, eating disorders, and inflammatory bowel disease, as well as those with recurrent low-impact fractures. The best test to screen for vitamin D is the serum 25-hydroxy-vitamin D (OH-D) level. Children with a deficiency (ie, 25-OH-D level <20 ng/mL) should be treated and retested in 6 to 8 weeks, Golden said. -Karen Rosenberg