PLoS one 10(8): e0136841. doi:1°.1371/journaLpone.0136841
Bruno D. Riverin1’2®, Jonathon L. Maguire3’4’5®, Patricia Li1’2® patricia.li at mcgill.ca
1 Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada,
2 Department of Epidemiology, Biostatistics & Occupational Health, McGill University, Montreal, Quebec, Canada,
3 The Applied Health Research Centre of the Li KaShing Knowledge Institute of St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada,
4 Department of Pediatrics, St. Michael’s Hospital, Toronto, Ontario, Canada, 5 Pediatric Outcomes Research Team (PORT), Division of Pediatric Medicine, Department of Pediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada ®
These authors contributed equally to this work.
- This meta-analysis, similar to most, ignores the dose size between studies (142 - 1200 IU daily)
Note the red-shaded box below (142 IU = 1,000 IU/ week)
- Each study gave the same dose ignoring differences in weight, existing Vitamin D level, etc.
- Can expect far more than 60% reduction when vitamin D supplement is adjusted for each child
See also VitaminDWiki
There is growing evidence that vitamin D plays a role in the pathogenesis of asthma but it is unclear whether supplementation during childhood may improve asthma outcomes.
We included RCTs that evaluated vitamin D supplementation in children versus active control or placebo for asthma.
Data Extraction and Synthesis
One reviewer extracted data and one reviewer verified data accuracy. We qualitatively summarized the main results of efficacy and safety and meta-analyzed data on comparable outcomes across studies. We used GRADE for strength of evidence.
Main Outcome Measures
Main planned outcomes measures were ED visits and hospitalizations. As secondary outcomes, we examined measures of asthma control, including frequency of asthma exacerbations, asthma symptom scores, measures of lung function, p2-agonist use and daily steroid use, adverse events and 25-hydroxyvitamin D levels.
Eight RCTs (one parallel, one crossover design) comprising 573 children aged 3 to 18 years were included.
One study (moderate-quality, n = 100) reported significantly less ED visits for children treated with vitamin D.
No other studies examined the primary outcome (ED visits and hospitalizations).
There was a reduced risk of asthma exacerbations in children receiving vitamin D (low-quality; RR 0.41,95% CI 0.27 to 0.63, 3 studies, n = 378).
There was no significant effect for asthma symptom scores and lung function.
The serum 25(OH)D level was higher in the vitamin D group at the end of the intervention (low-quality; MD 19.66 nmol/L, 95% CI 5.96 nmol/L to 33.37 nmol/L, 5 studies, n = 167).
We identified a high degree of clinical diversity (interventions and outcomes) and methodological heterogeneity (sample size and risk of bias) in included trials.
Conclusions and Relevance
Randomized controlled trials provide some low-quality evidence to support vitamin D supplementation for the reduction of asthma exacerbations. Evidence on the benefits of vitamin D supplementation for other asthma-related outcomes in children is either limited or inconclusive. We recommend that future trials focus on patient-relevant outcomes that are comparable across studies, including standardized definitions of asthma exacerbations.