Effects of infant formula enriched with butyrate on immune and intestinal functions

INTERVENTION: administation of a standard infant formula enriched with butyrate (30ml/L) given in sachets of 10 mg, administered three times a day for the first 28 days of life. In the first days of life we directly monitor the adherence to the intervention. Then we contact mothers CONDITION: prevention of immunological impairment in healty newborns PRIMARY OUTCOME: Development of innate immunity by measurement of beta‐defensins, cathelecidin LL‐37 in faecal and blood samples and development of adaptive immunity through the measurement of sIgA in faecal and blood samples Development of functional maturation of intestine through the monitoring of the citrulline levels in blood samples. SECONDARY OUTCOME: assessment of clinical improvement through evacuative patter, episodes of colic and crying, regurgitation, vomiting. These outcomes is assessed by daily diary completed by infant's mother. INCLUSION CRITERIA: Caucasian newborns exclusively fed artificially for maternal choice, gestational age greater than 37 weeks . Obtaining informed consent.