Kids' Bones at Risk From Low Vitamin D

July 9, 2007 -- Hours of playing video games and drinking sodas instead of milk may be putting children's bones at risk from low vitamin D levels.

A new study shows more than half of otherwise healthy children have low vitamin D levels in their blood, which may put them at risk for bone diseases, like rickets.

Vitamin D-fortified milk is the main source of vitamin D in the diet, but the vitamin is also produced within the body as a result of sunlight exposure.

That's why researchers say those low vitamin D levels may reflect current trends of children spending less time outdoors and drinking less milk than in the past.

Severely low levels of vitamin D can lead to muscle weakness, bone weakness, and rickets. Earlier studies -- cited by the researchers -- show that vitamin D also plays an important role in immune system function.

Vitamin D and Kids

In the study, published in the American Journal of Clinical Nutrition, researchers analyzed blood levels of vitamin D in 382 healthy children from ages 6 to 21.

They found 55% of the children had lower than recommended vitamin D levels.

African-American children, children over age 9, and those who didn't get much vitamin D in their diet were the most likely to have low levels of the vitamin in their blood.

Vitamin D levels also dropped during winter. Overall, 68% of children had inadequate stores of the vitamin in their blood during the colder months when they spent more time indoors.

"Vitamin D deficiency remains an under-recognized problem overall, and is not well studied in children," says researcher Babette Zemel, PhD, a nutritional anthropologist at Children's Hospital of Philadelphia, in a news release.

Zemel says more study is needed to determine appropriate blood levels of vitamin D in children, and a review of current recommendations for vitamin D intake may be needed.