A vitamin D deficiency could put kids at risk for a variety of health problems including weak bones.
Dr. Jonathan Mansbach calls the statistics for black and Hispanic children "astounding numbers" that should serve as a call to action. He's a researcher at Harvard Medical School and Children's Hospital in Boston.
Vitamin D deficiency in children, teens and adults is a concern because of recent studies suggesting the vitamin might help prevent serious diseases, including infections, diabetes and even some cancers.
Exactly how much vitamin D children and adults should get, and defining when they are deficient, is still under debate.