A prospective, double blind, placebo-controlled study with the aim to evaluate the effect of Lactobacillus reuteri supplementation on the immunological composition of breast milk in relation to sensitization and eczema in the babies.

The study included pregnant women supplemented with Lactobacillus reuteri ATTC 55730, 1 × 10^8 colony forming units daily (n=54) or placebo (n=55) from gestational week 36 until delivery, and their infants. Colostrum (first expressed milk) and mature milk were analysed for antibodies (total IgA, secretory IgA), pro- and anti-inflammatory cytokines (TNF, TGF-ß1, TGF-ß2, IL-10) and factors that may modify immune responses to bacteria (soluble CD14). Faecal samples from the mothers were analysed for the presence of live Lactobacillus reuteri cells.

The infants were supplemented with Lactobacillus reuteri (same dose as the mothers) from birth and until 12 months old. They were followed regarding development of eczema and sensitization (defined by a positive skin prick test and/or circulating food allergen-specific IgE antibodies) at 6, 12, and 24 months of age. Supplementation with Lactobacillus reuteri during pregnancy was associated with low levels of TGF-ß2 and slightly increased levels of IL-10 in colostrum. Infants that had received colostrum with low levels of TGF-ß2, were less likely to become sensitized during their first 2 years of life (p=0.01). A similar trend was observed for development of IgE-associated eczema.

Conclusion

Supplementation with Lactobacillus reuteri during late pregnancy reduced breast milk levels of TGF-ß2, and low levels of this immune factor were associated with less sensitization to allergens and possibly less IgE-associated eczema (eczema with hyperreactivity to allergy-causing substances such as egg and milk) in breast-fed infants.