title: Vitamin D insufficiency in the first 6 months of infancy and challenge-proven IgE-mediated food allergy at 1 year of age: a case-cohort study.
abstract: BACKGROUND
  Ecological evidence suggests vitamin D insufficiency (VDI) due to lower ambient ultraviolet radiation (UVR) exposure may be a risk factor for IgE-mediated food allergy. However, there are no studies relating directly measured VDI during early infancy to subsequent challenge-proven food allergy.
  
  
  OBJECTIVE
  To prospectively investigate the association between VDI during infancy and challenge-proven food allergy at 1 year.
  
  
  METHODS
  In a birth cohort (n = 1074), we used a case-cohort design to compare 25-hydroxyvitamin D3(25(OH)D3) levels among infants with food allergy vs a random subcohort (n = 274). The primary exposures were VDI (25(OH)D3<50 nM) at birth and 6 months of age. Ambient UVR and time in the sun were combined to estimate UVR exposure dose. IgE-mediated food allergy status at 1 year was determined by formal challenge. Binomial regression was used to examine associations between VDI, UVR exposure dose and food allergy and investigate potential confounding.
  
  
  RESULTS
  Within the random subcohort, VDI was present in 45% (105/233) of newborns and 24% (55/227) of infants at 6 months. Food allergy prevalence at 1 year was 7.7% (61/786), and 6.5% (53/808) were egg-allergic. There was no evidence of an association between VDI at either birth (aRR 1.25, 95% CI 0.70-2.22) or 6 months (aRR 0.93, 95% CI 0.41-2.14) and food allergy at 1 year.
  
  
  CONCLUSIONS
  There was no evidence that VDI during the first 6 months of infancy is a risk factor for food allergy at 1 year of age. These findings primarily relate to egg allergy, and larger studies are required.
authors.affiliation: School of Medicine, Deakin University, Waurn Ponds, VIC, Australia.|Child Health Research Unit, Barwon Health, Geelong, VIC, Australia.|Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Centre for Food and Allergy Research, Parkville, VIC, Australia.
authors.forename: J
authors.identifier: http://orcid.org/0000-0002-6935-0418
authors.initials: J
authors.lastname: Molloy
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Centre for Food and Allergy Research, Parkville, VIC, Australia.|Centre for Epidemiology and Biostatistics, The University of Melbourne, Carlton, VIC, Australia.
authors.forename: J J
authors.initials: JJ
authors.lastname: Koplin
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Centre for Food and Allergy Research, Parkville, VIC, Australia.|Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.|Department of Allergy and Immunology, Royal Children's Hospital, Parkville, VIC, Australia.
authors.forename: K J
authors.initials: KJ
authors.lastname: Allen
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Centre for Food and Allergy Research, Parkville, VIC, Australia.|Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.|Department of Allergy and Immunology, Royal Children's Hospital, Parkville, VIC, Australia.
authors.forename: M L K
authors.initials: MLK
authors.lastname: Tang
authors.affiliation: School of Medicine, Deakin University, Waurn Ponds, VIC, Australia.|Child Health Research Unit, Barwon Health, Geelong, VIC, Australia.|Murdoch Childrens Research Institute, Parkville, VIC, Australia.
authors.forename: F
authors.initials: F
authors.lastname: Collier
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Centre for Epidemiology and Biostatistics, The University of Melbourne, Carlton, VIC, Australia.|Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.
authors.forename: J B
authors.initials: JB
authors.lastname: Carlin
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Saffery
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.|Department of Paediatrics, Monash University, Clayton, VIC, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Burgner
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.|Department of Respiratory Medicine, Royal Children's Hospital, Parkville, VIC, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Ranganathan
authors.affiliation: The George Institute for Global Health, University of Oxford, Oxford, UK.
authors.forename: T
authors.initials: T
authors.lastname: Dwyer
authors.affiliation: School of Medicine, Deakin University, Waurn Ponds, VIC, Australia.
authors.forename: A C
authors.initials: AC
authors.lastname: Ward
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Moreno-Betancur
authors.affiliation: Biological and Molecular Mass Spectrometry Facility, Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Perth, Western Australia, 6009.
authors.forename: M
authors.initials: M
authors.lastname: Clarke
authors.affiliation: Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Centre for Food and Allergy Research, Parkville, VIC, Australia.
authors.forename: A L
authors.initials: AL
authors.lastname: Ponsonby
authors.affiliation: School of Medicine, Deakin University, Waurn Ponds, VIC, Australia.|Child Health Research Unit, Barwon Health, Geelong, VIC, Australia.|Murdoch Childrens Research Institute, Parkville, VIC, Australia.|Centre for Food and Allergy Research, Parkville, VIC, Australia.
authors.forename: P
authors.initials: P
authors.lastname: Vuillermin
mesh_terms: D000367:Age Factors; D016022:Case-Control Studies; D015331:Cohort Studies; D004032:Diet / Q000009:adverse effects; D004781:Environmental Exposure; D005260:Female; D005512:Food Hypersensitivity / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D007114:Immunization; D007073:Immunoglobulin E / Q000276:immunology*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011159:Population Surveillance; D015995:Prevalence; D012307:Risk Factors; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000453:epidemiology* / Q000209:etiology
chemical_list: D014807:Vitamin D; D007073:Immunoglobulin E
keywords: cohort; eczema; food allergy; paediatrics; vitamin D