Background Oral tolerance induction in early life is a promising approach for food allergy prevention. Its success requires the identification of factors necessary for its persistence. Objectives We aimed to assess in mice duration of allergy prevention by breastfeeding-induced oral tolerance and whether oral TGF-β supplementation after weaning would prolong it. Methods We quantified ovalbumin (OVA) and OVA specific immunoglobulins levels by ELISA in milk from the EDEN birth cohort. Since OVA specific Ig were found in all samples, we assessed whether OVA-immunized mice exposed to OVA during lactation could prevent allergic diarrhea in their 6 and 13-week-old progeny. In some experiments, a TGF-β enriched formula was given after weaning. Results At 6 weeks, only 13% and 34% of mice breastfed by OVA-exposed mothers exhibited diarrhea after 6 and 7 OVA challenges versus 44% and 72% in mice breastfed by naive mothers (p=0.02 and 0.01). Protection was associated with decreased levels of MMCP1 and OVA specific IgE (p
