Children with severe therapy-resistant asthma (STRA) may have poorer lung function and worse symptoms compared to children with moderate asthma, due to lower levels of vitamin D in their blood, according to researchers in London. Lower levels of vitamin D may cause structural changes in the airway muscles of children with STRA, making breathing more difficult. The study provides important new evidence for possible treatments for the condition. The findings were published online ahead of the print edition of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine. "This study clearly demonstrates that low levels of vitamin...