Early Feeding Practices and Celiac Disease Prevention: Protocol for an Updated and Revised Systematic Review and Meta-Analysis.

Uncertainty remains in regard to when, how, and in what form gluten should be introduced into the diet, particularly of infants genetically predisposed to developing celiac disease (CD). MEDLINE (PubMed), EMBASE, and Cochrane Central Register of Controlled Trials databases will be searched from inception. Randomized controlled trials (RCTs) and observational studies (cohort, case-control, or cross-sectional studies) investigating the association between early feeding practices and the risk of CD and/or CD autoimmunity will be included. In prospective studies, participants will be infants regardless of the risk of developing CD. For retrospective studies, participants will be children or adults with CD or presenting with positive serology indicative of CD. Interventions will be gluten-containing products of any type. Exposures will be breastfeeding and/or the introduction of gluten-containing products of any type. In control groups, there will be no exposure, different degrees of exposure (partial vs. exclusive breastfeeding, different amounts of gluten, etc.), or a placebo. The primary outcome measure will be CD or CD autoimmunity (i.e., anti-transglutaminase or anti-endomysial antibodies). At least two reviewers will independently assess the risk of bias using a validated risk assessment tool depending on study design. Disagreements will be resolved by discussion to achieve a consensus with the involvement of one or more additional reviewers if required. If appropriate, data will be pooled. If not, a narrative synthesis will be performed. The findings will be submitted to a peer-reviewed journal.