A study published in December 2012 reports that supplementation with vitamin D3 reduces infections in individuals with increased susceptibility to recurrent respiratory infections. It is estimated that the average adult has two to three upper respiratory infection-type illnesses per year, while the average child has six to 10 per year.
In this double-blind randomized-controlled trial, researchers assessed 140 subjects with antibody deficiency, including selective IgA subclass deficiency, IgG subclass deficiency or common variable immune disorder; and subjects with four or more respiratory tract infections of per year without immunological diagnosis.
The subjects received 4,000 IU vitamin D3 or placebo daily for one year. The investigators evaluated the subjects for respiratory tract infection symptoms, malaise, antibiotic consumption, serum 25-hydroxyvitamin D3 levels, microbiological findings and levels of antimicrobial peptides LL-37 and HNP1-3 in nasal fluid. The scientists used this data to calculate an overall infectious score.
The researchers determined that the overall infectious score was significantly reduced in the subjects receiving vitamin D3 supplementation compared to the placebo group. More specifically, the researchers showed that the vitamin D group had an overall infectious score of 202, as compared to the placebo group with a score of 249.
The study authors concluded, “Supplementation with vitamin D3 may reduce disease burden in patients with frequent respiratory tract infections.”
Bergman P, et al. BMJ Open. 2006