Vitamin D deficiency may be a common but unrecognized problem among U.S. adolescents, new study findings suggest.

Researchers found that among 11- to 18-year-olds living in Boston, nearly one-quarter were deficient in vitamin D, a nutrient that aids in calcium absorption and is vital for healthy bone development.

That so many adolescents were low on the vitamin is both surprising and “very concerning,” according to lead study author Dr. Catherine M. Gordon of Children’s Hospital Boston.

“The problem occurred at a much higher rate than we expected,” she told Reuters Health, noting that “we shouldn’t have vitamin D deficiency in this country.”

That’s because the problem is preventable with an adequate diet and time outdoors. The body naturally synthesizes vitamin D when the skin is exposed to the sun, and milk and certain other foods, including many breakfast cereals, are fortified with the vitamin.

But U.S. children increasingly fill up on soft drinks at the expense of milk, and spend more time in front of the TV or computer than outdoors.

Gordon pointed out that her study found that soft drink, juice and iced tea intake were related to a greater risk of vitamin D deficiency. On the other hand, adolescents who said they drank milk and ate cereal were less likely to be low on the vitamin.

The findings are published in the Archives of Pediatrics & Adolescent Medicine.

For the study, the researchers analyzed blood samples from 307 healthy adolescents who had routine physical exams between 2001 and 2003. They found that 24 percent of the children were vitamin D deficient, and nearly 5 percent were severely deficient.

African-American adolescents had the highest prevalence of vitamin D deficiency, with 36 percent affected. Sunlight, the researchers note, is less efficient at triggering vitamin D synthesis in darker skin.

Gordon and her colleagues did find lower rates of vitamin D deficiency in the summer and fall - but even during these sun-filled months, 12 to 17 percent of adolescents were low on the vitamin.

To guard against the problem, children and teens should get regular outdoor activity and consume vitamin D-fortified foods, according to Gordon. She noted that for children who turn their noses up at milk, there are some juices available that contain added vitamin D.

Multivitamins are also a good option, she said, particularly for kids whose diets may be lacking in a number of nutrients.

The findings also pose the question of whether children and teens should be routinely screened for vitamin D deficiency, Gordon pointed out. As it stands, deficiency may be suspected in children with a history of bone fractures, but most kids will never be screened for vitamin D status.

The high rate of deficiency among healthy adolescents in this study suggests screening “is something we need to look at,” Gordon said.

SOURCE: Archives of Pediatrics & Adolescent Medicine, June 2004.