Cow's milk allergy (CMA) is the most common food allergy in early childhood, with an estimated incidence ranging between 2% and 3% in infants and marginally lower in older children. It has been demonstrated that it could be a risk factor for the development of the functional gastrointestinal disorders in children. Intestinal microflora has been indicated as potential target for the management of CMA and FGDIs through the use of probiotics. Lactobacillus rhamnosus GG (LGG) is the most studied probiotic. Recently, it has been demonstrated that an extensively hydrolyzed casein formula remains hypoallergenic following the addition of LGG, satisfying both the American Academy of Pediatrics guidelines. Lactobacillus GG exerts several benefits when added to an extensively hydrolyzed casein formula (Nutramigen LGG), including decreased severity of atopic dermatitis, improved recovery of intestinal symptoms in infants with CMA-induced allergic colitis, and faster induction of tolerance in infants with CMA. The mechanisms of these effects are multiple and exerted at different levels: epithelium, immune system and enteric nervous system. Studies and meta-analyses showed that LGG increases treatment success in children with functional gastrointestinal disorders.

Inclusion Criteria:

• Children (aged from 4 to 6 yrs) with a history of sure diagnosis of cow's milk allergy obtained in the first year of life treated with hypoallergenic formula

Exclusion Criteria:

• Age higher than 12 months,
• concomitant chronic systemic diseases,
• congenital cardiac defects,
• active tuberculosis,
• autoimmune diseases,
• immunodeficiency,
• chronic inflammatory bowel diseases,
• celiac disease,
• cystic fibrosis,
• metabolic diseases,
• malignancy,
• chronic pulmonary diseases,
• malformations of the gastrointestinal tract,
• suspected eosinophilic esophagitis or eosinophilic enterocolitis,
• suspected food-protein-induced enterocolitis syndrome,
• suspected cow's milk proteins-induced anaphylaxis.

The study population will be enrolled from a cohort of about 300 children (aged from 4 to 6 yrs) with a history of sure diagnosis of CMA obtained in the first year of life treated with hypoallergenic formula for at least 6 months and who are already in follow-up at the Department of Pediatrics of University of Naples "Federico II".