New studies show 70 percent of children and adolescents in the U.S. do not get enough vitamin D.
 
Nine percent, or 7.6 million children across the country, were vitamin D deficient and another 61 percent, or 50.8 million, were vitamin D insufficient. 

That puts them at risk for everything from brittle bones to heart disease.

"Several small studies had found a high prevalence of vitamin D deficiency in specific populations of children, but no one had examined this issue nationwide," said study leader Dr. Michal L. Melamed of the Albert Einstein College of Medicine of Yeshiva University.

Researchers examined data on more than 6,000 children, between the ages of 1 to 21, which was collected by the National Health and Nutrition Examination Survey from 2001-2004.

Low levels were especially common in girls, African-Americans, Mexican-Americans, and those who spent more than four hours a day watching TV, playing video games, or using computers.
    
Doctors call the findings a critical wake-up call to parents across the country.

Source: Live Science