PURPOSE OF THE STUDY.
The goal of this study was to evaluate the association of maternal cow’s milk (CM) avoidance during breastfeeding with specific IgA levels in human milk and the development of CM allergy in infants.
This prospective birth cohort study evaluated 145 mother–infant pairs who were recruited at birth and followed up prospectively at 0 to 2 weeks and at 1, 3, 6, 12, and 18 months to determine development of food allergy in the infants. Infants were all term and classified into 2 groups: high risk because of sibling(s) with food allergy and low risk, defined as having only nonatopic first-degree relatives.
Human milk and/or serum samples were obtained from 286 visits with an average of 2 visits per each mother–infant pair. Maternal and infant diets were obtained by using dietary records. Thirty-seven mothers implemented a strict maternal CM avoidance diet within the first 3 months’ postpartum, 49 mothers started a CM elimination diet between 3 and 7 months of breastfeeding, and 56 mothers continued CM in their diet without restrictions. Seventy-five infants in this cohort developed challenge-proven CM allergy. Maternal serum samples and breast milk samples were assayed for casein and β-lactoglobulin (BLG)-specific IgA and IgG by using an enzyme-linked immunosorbent assay. Infants’ sera were evaluated for casein and BLG-specific IgA, IgG, and IgE. The impact of human milk on β-lactoglobulin uptake was assessed in transcytosis assays by using Caco-2 intestinal epithelial cell lines.
Breast milk samples (n = 23) from mothers avoiding CM had lower casein- and BLG-specific IgA levels than milk from mothers (n = 56) with no CM restriction (P = .019 and P = .047, respectively). Their infants had lower serum casein- and BLG-specific IgG1 (P = .025 and P < .001) and BLG-specific IgG4 (P = .037) levels, and their casein- and BLG-specific IgA levels were less often detectable than those with no CM elimination diet (P = .003 and P = .007). Lower CM-specific IgG4 and IgA levels, in turn, were associated with infant CM allergy. In the in vitro model for evaluating the transcytosis of BLG through enterocytes, high levels of BLG-specific IgA (the no CM restriction group) in breast milk impaired movement of BLG across the “gut mucosa.”
Maternal avoidance of CM was associated with lower levels of mucosal-specific IgA levels and the development of CM allergy in infants.
This article refutes the practice of food avoidance during breastfeeding. Maternal elimination diets resulted in lower levels of breast milk–specific IgA, which was associated with the development of CM allergy in infants. The study found that human milk IgA may play a role in preventing excessive food antigen uptake in the gut lumen and thereby possibly prevent the development of CM allergy. The participants chosen for this study, however, had a significant atopic family history, which could mean application to the general population may not be as straightforward. Further research with elimination diets and other allergenic foods in a less atopic study population is necessary to confirm the relationship between dietary restriction, breastfeeding, and the development of pediatric food allergy.
- Copyright © 2014 by the American Academy of Pediatrics