Vitamin D in Asthma

Abstract

45 46There is increasing interest in the therapeutic utility of vitamin D in asthma, supported by a 47

Randomized phase 2 trial of monthly vitamin D to prevent respiratory complications in children with sickle cell disease

“…23 A recent Cochrane review of randomized clinical trials identified high-quality evidence that vitamin D supplementation reduced the risk for asthma exacerbations, although too few pediatric trials were included to permit definitive conclusions for children. 24,25 Although observational studies have consistently found significant associations between low vitamin D levels and increased susceptibility to respiratory infections, randomized clinical trials examining the effects of vitamin D supplementation on the risk for respiratory infections have had conflicting findings that are due, in part, to differences in the baseline status of the participants, the duration of the studies, and the amount and frequency of dosing. [26][27][28][29] Children with sickle cell disease are at high risk for vitamin D deficiency due to limited sun exposure, dark skin color, and poor nutrition.…”

Targeting the exposome: does correcting vitamin D deficiency have potential to treat and prevent asthma?

“…Multiple epidemiological studies have identified strong associations between vitamin D deficiency and different aspects of asthma [5]. In support of these associations being biologically important, there are now convincing findings from clinical trial meta-analyses that show vitamin D supplementation of appropriate patients significantly reduces their rate of exacerbations requiring systemic corticosteroids [3,6,7]. Not only is the effect statistically significant but also clinically significant with a recent individual patient data meta-analysis by Jolliffe and colleagues finding an adjusted incidence rate ratio of 0.74 in favor of reduced exacerbations with vitamin D supplementation versus placebo (95% confidence interval 0.56-0.97; p = 0.03) [6].…”

“…Despite the potential for interventions targeted at 'correcting' the individual's exposome to be cost-effective and extremely safe compared to traditional pharmacotherapies, comparatively few trials have been undertaken of such interventions in asthma. Vitamin D stands out as the environmental factor most rigorously investigated in asthma and lessons learnt from these studies are important in considering other potential treatments for asthma that target the exposome [3].…”

“…Not only is the effect statistically significant but also clinically significant with a recent individual patient data meta-analysis by Jolliffe and colleagues finding an adjusted incidence rate ratio of 0.74 in favor of reduced exacerbations with vitamin D supplementation versus placebo (95% confidence interval 0.56-0.97; p = 0.03) [6]. Not all clinical trials have however shown vitamin D to be beneficial in asthma with discordant trial findings likely a result of heterogeneity in study design and under-powering of some studiesincreasing understanding of vitamin D biology has now revealed major considerations for vitamin D supplementation not known when some of the clinical trials were designed [3]. For example, regular dosing appears more beneficial than the infrequent bolus dosing that has been used in some vitamin D trials.…”

“…Vitamin D also inhibits inflammatory pathways induced by Alarmin cytokines such as IL-33, for example by promoting secretion of the soluble decoy receptor sST2 and inhibitory effects on responder cells [3,15].…”