title: The role of circulating 25 hydroxyvitamin D in asthma: a systematic review.
abstract: Asthma is a major public health issue. The co-occurrence of the high prevalence of asthma and vitamin D deficiency documented globally in recent decades has prompted several investigations into a possible association between the two conditions. The objective of this paper was to synthesize the evidence from studies that have measured the association between serum vitamin D and asthma incidence, prevalence, severity and exacerbations. A systematic search of the literature was performed in PubMed, and the available evidence was summarized both qualitatively and by meta-analysis. Only English language, observational studies measuring serum levels of 25(OH)D as the exposure were included, as this is the most robust measure of vitamin D levels. The search identified 23 manuscripts: two case-control, 12 cohort and nine cross-sectional studies. Collectively, the evidence suggests that higher serum levels of 25(OH)D are associated with a reduced risk of asthma exacerbations, but there was little evidence to suggest an association with asthma incidence, prevalence or severity. A significant amount of heterogeneity between study methodology and results restricted the scope for meta-analysis. These results suggest that vitamin D supplementation may be effective for the prevention of asthma exacerbations, but the findings need to be confirmed by clinical trials.
authors: Allergy and Lung Health Unit, School of Population and Global Health, University of Melbourne, Carlton, Vic, Australia.
authors: R
authors: R
authors: Cassim
authors: M A
authors: MA
authors: Russell
authors: C J
authors: CJ
authors: Lodge
authors: A J
authors: AJ
authors: Lowe
authors: J J
authors: JJ
authors: Koplin
authors: S C
authors: SC
authors: Dharmage
mesh_terms: D001249:Asthma / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D018450:Disease Progression; D006801:Humans; D015994:Incidence; D063868:Patient Outcome Assessment; D015995:Prevalence; D012720:Severity of Illness Index; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000150:complications
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25 hydroxyvitamin D; asthma; review; systematic