 Epidemiological and observational studies have linked vitamin D deficiency with increased asthmaallergy incidence . Vitamin D insufficiency 75nmolL has been associated with increased incidence of severe childhood asthma. Further, high 25OHD levels were associated with reduced risk of recent hospitalization, lower use of anti-asthmatic medication and lower airway hyper-responsiveness in childhood asthmatics. The association between vitamin D and allergy and asthma appears to be stronger in children than adults, with some even suggesting that childhood asthma may may be caused by VDD. 