Background: The establishment of the beneficial interactions between the host and its microbiota is essential for the development and correct functioning of the organism, since microflora alterations can lead to many chronic degenerative diseases. In this context, probiotics are used to improve balanced microbial communities and therefore exert substantial health-promoting effects to the host.

Objective: The aim of the present study is to monitor the molecular outcomes, obtained by gut microflora modulation through probiotic treatment, on human urine and serum metabolic profiles, with a 1H-Nuclear Magnetic Resonance -based metabolomic approach.

Design: In a first phase twenty-two healthy subjects are enrolled in the study and administered with Lactobacillus delbrueckii subs. delbrueckii and/or a mix of 5 biotypes of Bifidobacterium longum for 8 weeks. In the second phase subjects are enrolled in the study and administered with Lactobacillus rhamnosus, Lactobacillus plantarum, Lactobacillus fermentum and Bifidobacterium longum at two different concentration. During the course of the study all the probiotic types were administered both singularly and in combination. From each subject urine and serum samples are collected before and during the supplementation and are analysed by nuclear magnetic resonance spectroscopy and statistical analyses.

Inclusion Criteria:

- healthy subjects

Exclusion Criteria:

• previous surgery on the intestinal tract;
• a probiotic / prebiotic and antibiotic treatments within 3 and 1 months, respectively, before the beginning of the study;
• subjects have changed drastically their diet or lifestyle during the study.