Is antenatal or early‐life vitamin D associated with eczema or food allergy in childhood? A systematic review

Abstract

AbstractObjectiveTo summarise the associations between antenatal or early‐life blood vitamin D and the development of eczema/food allergy in childhood.DesignA systematic review and meta‐analyses were conducted to synthesize the published literature. Two reviewers independently performed the study selection and data extraction on Covidence. We assessed the risk of bias for observational studies by using the Newcastle‐Ottawa Scale and the Cochrane Risk of Bias tool for clinical trials. The certainty of the evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluations (GRADE).Data sourcesWe systematically searched PubMed and Embase from inception and April 2022.Eligibility criteriaHuman studies that investigated prospective associations between antenatal or early‐life blood vitamin D levels, dietary intake or supplementation and childhood eczema/food allergy.ResultsForty‐three articles including six randomised controlled trials (RCTs) were included. Four RCTs of vitamin D supplementation during pregnancy showed no evidence of an effect on the incidence of eczema (pooled odds ratio [OR] = 0.85; 0.67–1.08, I2 = 6.7%, n = 2074). Three RCTs reported null associations between supplementation in pregnancy/infancy and food allergy. From six cohort studies, increasing cord blood vitamin D levels were associated with reduced prevalence of eczema at/close to age one (OR per 10 nmol/L increase = 0.89; 0.84–0.94, I2 = 0%, 2025 participants). We found no evidence of an association between maternal antenatal or infant vitamin D level or dietary intake and the development of food allergy or eczema in offspring.ConclusionsWe found an association between higher vitamin D levels in cord blood and reduced risk of eczema in cohort studies. Further trials with maternal and infant supplementation are needed to confirm if vitamin D supplementation can effectively prevent eczema or food allergy in childhood.Systematic review registrationPROSPERO, No. CRD42013005559.