Background The effects of breastfeeding and probiotics on infant sensitization still remain discrepant.
Objective To explore probable explanatory factors in infant sensitization and the protective effect of probiotics.
Methods Altogether 171 mother–infant pairs from an ongoing placebo-controlled double-blind study with nutrition modulation by dietary counselling and probiotic supplementation were studied. Skin prick testing was done in infants at 6 and 12 months and in mothers at third trimester of pregnancy. The breast milk concentrations of cytokines TGF-β2, soluble CD14, IFN-γ, TNF-α, IL-10, IL-6, IL-4 and IL-2 were measured.
Results The risk of sensitization increased in infants with allergic mothers breastfeeding over 6 months [odds ratio (OR=4.83, P=0.005)], or exclusively breastfeeding over 2.5 months (OR=3.4, P=0.018). Probiotic supplementation had a protective effect against sensitization in infants with a high hereditary risk due to maternal sensitization (OR=0.3, P=0.023). The concentration of TGF-β2 tended to be higher in the colostrum of the mothers in the probiotic group as compared with those on placebo (probiotic/placebo ratio=1.50, P=0.073). A similar result was obtained in the subgroup of allergic mothers (probiotic/placebo ratio=1.56, P=0.094).
Conclusion Infants of atopic mothers, specifically when breastfed exclusively over 2.5 months or totally over 6 months, had a higher risk of sensitization at the age of 12 months. This risk could be reduced by the use of probiotics during pregnancy and lactation, partly by resulting in a beneficial composition of the breast milk.