Vitamin D as an adjunctive therapy in asthma. Part 2: A review of human studies.
Vitamin D deficiency (VDD) is highly prevalent worldwide, with adverse effects on bone health but also potentially other unfavorable consequences. VDD and asthma-incidence/severity share many common risk factors, including winter season, industrialization, poor diet, obesity, dark skin pigmentation, and high latitude. Multiple anatomical areas relevant to asthma contain both the enzyme responsible for producing activated vitamin D and the vitamin D receptor suggesting that activated vitamin D (1,25-dihydroxyvitamin D) may have important local effects at these sites. Emerging evidence suggests that VDD is associated with increased airway hyperresponsiveness, decreased pulmonary function, worse asthma control, and possibly decreased response to standard anti-asthma therapy. However the effect is inconsistent with preliminary evidence from different studies suggesting vitamin D is both beneficial and detrimental to asthma genesis and severity. Current evidence suggests that supplementation with moderate doses of vitamin D may be appropriate for maintenance of bone health in asthmatics, particularly steroid users. However emerging data from an increasing number of randomized, controlled, intervention studies of vitamin D supplementation in pediatric and adult asthma are becoming available and should help determine the importance, if any of vitamin D for asthma pathogenesis. The purpose of this second of a two-part review is to review the current human literature on vitamin D and asthma, discussing the possible consequences of VDD for asthma and the potential for vitamin D repletion as adjunct therapy.
Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland; School of Medicine and Medical Sciences, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: conorkerley@gmail.com.
Conor P
CP
Kerley
Department of Paediatric Respiratory Medicine, The National Children's Hospital Dublin 24, Ireland. Electronic address: basil.elnazir@amnch.ie.
Basil
B
Elnazir
Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland. Electronic address: doctorfaul@gmail.com.
John
J
Faul
Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland. Electronic address: liamcormican@rcsi.ie.
Liam
L
Cormican
D000328:Adult; D000818:Animals; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology; D002648:Child; D019587:Dietary Supplements; D006801:Humans; D018167:Receptors, Calcitriol / Q000378:metabolism; D014807:Vitamin D / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology; D014808:Vitamin D Deficiency / Q000453:epidemiology; D014815:Vitamins / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology
D018167:Receptors, Calcitriol; D014815:Vitamins; D014807:Vitamin D
Airway; Allergy; Asthma; Diet; Epidemiology; Nutrition; Sun; Vitamin D