Increased vitamin D intakes may reduce infectious symptoms

February 6, 2013

Regular high doses of vitamin D3 can reduce symptoms of respiratory tract infections and antibiotic consumption among patients with an increased frequency of infections, suggest a new Swedish study.

In the randomized controlled trial, 140 patients with increased susceptibility to respiratory tract infections received a daily vitamin D3 supplement (4000 IU) or a placebo for one year (1). The study results showed that vitamin D3 supplementation significantly reduced symptoms and antibiotic consumption among the pa-tients compared to the placebo group. Its effect on the symptoms can be translated follows: A cough could be reduced by 47 days, ear and sinus symptoms could be reduced by 23 days, and a combination of a cough, sinus and ear symptoms, malaise and antibiotic consumption could be reduced by 9 days. In addition, the probability of taking antibiotics was reduced by approximately 60%.

The researchers concluded that vitamin D3 supplementation may reduce disease burden in patients with recurrent respiratory tract infections. Vitamin D3 could provide a novel strategy to reduce antibiotic use among high consumers and indirectly prevent the emerging epidemic of bacterial resistance. Recent evidence suggests that vitamin D3 has potent extraskeletal effects, such as suppression of inflammation
and strengthening of mucosal immunity by induction of antimicrobial peptides (2). Data from observational studies indicate that low levels of 25-hydroxyvitamin D3 are associated with an increased risk of respiratory tract infections (3), while results from a limited number of randomized controlled trials on the protective role of vitamin D against respiratory tract infections are inconclusive.


  1. Bergmann P. et al. Vitamin D3 supplementation in patients with frequent respiratory tract infections: a randomised and double-blind intervention study. BMJ Open. Published online January 2013.
  2. Liu P. T. et al. Toll-like receptor triggering of a vitamin D-mediated human antimicrobial response. Science. 2006; 311:1770–1773.
  3. Ginde A. A. et al. Association between serum 25-hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey. Arch Inter Med. 2009; 169:384–390.