A study appearing in the American Journal of Critical Care Medicine (14 January 2010, epublished ahead of print) found a relationship between vitamin D leveles and the severity of asthma symptoms. The subjects of the study were 54 nonsmoking adults. The airways were more hyporesponsive and lung function was more impaired in those with low vitamin D levels. Better lung function and better responsiveness to glucocorticoid treatment were found in these with adequate vitamin D levels.