The Importance of Vitamin D Levels in Recovering From Respiratory Ailments

Vitamin D Supplementation to Prevent Acute Respiratory Tract Infections: Systematic Review and Meta-Analysis of Individual Participant Data

“Acute respiratory tract infections are a major cause of global morbidity and mortality and are responsible for 10% of ambulatory and emergency department visits in the USA and an estimated 2.65 million deaths worldwide in 2013. Observational studies report consistent independent associations between low serum concentrations of 25-hydroxyvitamin D (the major circulating vitamin D metabolite) and susceptibility to acute respiratory tract infection. 25-hydroxyvitamin D supports induction of antimicrobial peptides in response to both viral and bacterial stimuli, suggesting a potential mechanism by which vitamin D inducible protection against respiratory pathogens might be mediated. Vitamin D metabolites have also been reported to induce other innate antimicrobial effector mechanisms, including induction of autophagy and synthesis of reactive nitrogen intermediates and reactive oxygen intermediates. These epidemiological and in vitro data have prompted numerous randomised controlled trials to determine whether vitamin D supplementation can decrease the risk of acute respiratory tract infection. A total of five aggregate data meta-analyses incorporating data from up to 15 primary trials have been conducted to date, of which two report statistically significant protective effects and three report no statistically significant effects. All but one of these aggregate data meta-analyses reported statistically significant heterogeneity of effect between primary trials. . .

Analysis of 25 randomized controlled trials from around the world found that vitamin D supplementation cut the risk of respiratory tract infections by 50% in people that were deficient and by 10% in people with normal vitamin D levels.”