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.
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.
['Molloy|J|J|http://orcid.org/0000-0002-6935-0418', 'Koplin|J J|JJ|', 'Allen|K J|KJ|', 'Tang|M L K|MLK|', 'Collier|F|F|', 'Carlin|J B|JB|', 'Saffery|R|R|', 'Burgner|D|D|', 'Ranganathan|S|S|', 'Dwyer|T|T|', 'Ward|A C|AC|', 'Moreno-Betancur|M|M|', 'Clarke|M|M|', 'Ponsonby|A L|AL|', 'Vuillermin|P|P|', '|||']
D000367:Age Factors D016022:Case-Control Studies D015331:Cohort Studies D004032:Diet D004781:Environmental Exposure D005260:Female D005512:Food Hypersensitivity D006801:Humans D007114:Immunization D007073:Immunoglobulin E D007223:Infant D007231:Infant, Newborn D008297:Male D011159:Population Surveillance D015995:Prevalence D012307:Risk Factors D014466:Ultraviolet Rays D014807:Vitamin D D014808:Vitamin D Deficiency
vitamin D food allergy cohort eczema paediatrics