02420nas a2200277   4500000000100000008004100001100001200042700001300054700001300067700001200080700001100092700001400103700001300117700001400130700001400144700001800158700001100176700002200187700001300209700001500222700001700237700002700254245014700281520170000428022001402128       2017                            d1 aDwyer T1 aMolloy J1 aKoplin J1 aAllen K1 aTang M1 aCollier F1 aCarlin J1 aSaffery R1 aBurgner D1 aRanganathan S1 aWard A1 aMoreno-Betancur M1 aClarke M1 aPonsonby A1 aVuillermin P1 aBIS Investigator Group00aVitamin 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.3 a<p>
<b>BACKGROUND: </b>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.
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<b>OBJECTIVE: </b>To prospectively investigate the association between VDI during infancy and challenge-proven food allergy at 1 year.
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<b>METHODS: </b>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 &lt;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.
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<b>RESULTS: </b>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.
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<b>CONCLUSIONS: </b>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.
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