Fermented milks are sources of bioactive peptides that modulate intestinal functions. Hydrolysates fermented by: Lactobacillus paracasei, Enterococcus faecalis, Enterococcus faecium, Bifidobacterium longum, Lactobacillus plantarum and Sstreptococcus thermophillus were studied by electrophoresis and chromatography. Antioxidant activity and the effects on the intestine of mice sensitised to β-Lg and milk, followed by histology of the jejunum, were undertaken. The results showed proteolytic performance and antioxidant capacity. The preventive effect showed a slight production of anti-Blg IgG and IgE. The Ussing chamber shows that the response to allergen stimulation is lower. The histological study revealed, in the groups that received hydrolysates, minor damage with weaker inflammatory signs and villi that were more or less enlarged. Hydrolysates have a preventive and therapeutic effect and appear to have a protective effect on the intestinal epithelium. The L.paracasei strain is an interesting candidate, since its therapeutic and preventive effects are more marked.