D Minus: Dearth of Vitamin D Is Common in Kids (US News & World Report) Researchers at Children's Hospital of Philadelphia have found that 55 percent of otherwise healthy children and teenagers they tested had inadequate amounts of vitamin D in their blood. In many cases, the lack of D was enough to interfere with calcium absorption and healthy bone development. In addition to building strong bones, vitamin D helps the body's immune system function, and scientists ... [News Source]