In the last years manipulation of intestinal microbiota with probiotics has gained an increasing interest, specially in infant nutrition since recent studies has demonstrated the presence of probiotics in human milk. However, there are few studies studying the effects of probiotics in newborns. The objective of the present study is to analyze safety and tolerance of the probiotic Lactobacillus fermentum CECT5716 isolated from human milk.

Inclusion Criteria:

• Healthy 1 month infants exclusively formula-fed

Exclusion Criteria:

• gastrointestinal disorders (history of chronic diarrhoea or constipation, gastroesophageal reflux)
• gastrointestinal surgery
• cow's milk protein allergy
• metabolic disorders (diabetes, lactose intolerance)
• immune deficiency
• antibiotic prescription 1-week prior to inclusion and previous use of formula containing prebiotics or probiotics