Vitamin D Levels Inversely Linked With URTI

According to the results of a secondary analysis of the Third National Health and Nutrition Examination Survey, serum 25-hydroxyvitamin D [25(OH)D] levels are inversely associated with recent upper resperatory tract infected (URTI), particularly in those with cronic respiratory tract diseases.
“Recent studies suggest a role for vitamin D in inrate immunity, including the prevention of resperatory tract infections (RTIs),” said Adit A. Ginde, MD, MPH from university of Colorado Denver School of Mediciine In Aurora, and colleagues. ” We hypothesize that serum 25(OH)D levels are inversely associated with recent URTI.”
The investigators conducted a probability survey of the US population performed between 1988 and 1994 and evaluated the association between 25(OH)D levels and recent URTI in 18,883 participants, twelve years or older, both with and without adjustment for demographic and clinical factors including season, body mass index, smoking history, asthma and chronic onstructive pulmonary disease (CPD).
Limitations of the study include inability to make casual inference, primary outcome of recent URTI based on self report, and serum samples collected at only one piont in the time.
The study authors concluded that “although 25(OH)D levels less than 30 ng/ml and URTI were higher in winter seasons, the inverse association was precent throughout the year. individuals with respiratory tract diseases such as asthma who have low serum 25(OH)D levels may be even susceptible or RTI. Vitamin D supplementation may reduce the incidence of URTI and exacerbations of respiratory tract diseases.