 Method: 36 Infants in exclusive breastfeeding, 36 infants feeding exclusively on infant formula with synbiotics and 36 infants following mixed nutrition with breast milk and infant formula with synbiotics, for a period of 3 months have been selected on randomized basis. For all these three groups, the anthropometric parameters should be measured length, weight, head perimeter, since the first day of newborns inclusion in the trial and at the age of 15 days, 2 and 3 months. Moreover, at the age of 15 days, 2 months, 3 months and on the infants inclusion day in the trial, newborns-infants urine sample should be collected by the attending doctor using a ball of cotton inserted into the disposable diaper and with the aid of an aspiration syringe the urine sample 2-3 ml will be transferred to a sterile vial and finally stored at -80 C. Then frozen urine samples will be sent in batches to a contracted diagnostic center in order to examine the metabolic profile of the three diets described above exclusive breastfeeding, infant formula with synbiotics and mixed nutrition with breast milk and infant formula with synbiotics, with the help of NMR and selectively liquid chromatography mass spectrometry LCMS. This urine collection gives reliable results and can be used in infants without causing any discomfort or side-effect. 