Inadequate vitamin D status is highly prevalent in children worldwide, even in equatorial regions with lots of sunshine. Recent epidemiologic studies indicate that low plasma vitamin D concentrations are related to increased incidence of respiratory infections, including acute lower respiratory tract infections and respiratory syncytial virus (RSV) disease in infants and children less than 5 years of age. Furthermore, vitamin D supplementation in randomized controlled trials conducted among schoolchildren resulted in reduced incidence of influenza A infection and acute respiratory infection.
Among school-age children, respiratory and gastrointestinal infections account for increased school absences and parental absenteeism from work, as well as a sizeable proportion of physician visits.
