Impact of the synbiotic combination of Lactobacillus casei shirota and oligofructose-enriched inulin on the fecal volatile metabolite profile in healthy subjects

Scope: Hypothesis-driven approaches have mainly focused on the quantification of SCFAs as mediators of beneficial effects of synbiotics. However, the emergence of metabolite profiling strategies allows to evaluate the colonic metabolism from a top-down approach. In the present study, we evaluated the impact of a synbiotic combination on fecal metabolite profiles. Methods and results: A synbiotic combination ( Lactobacillus casei Shirota cells+oligofructose-enriched inulin) was evaluated in nine healthy volunteers. Before the start, during and after 4-wk treatment, fecal samples were obtained. GC-MS technology was applied to analyze the volatile metabolites. Application of a Type III test revealed that the metabolite profiles from the three conditions were significantly different. We identified three volatile organic compounds, acetate, dimethyl trisulfide and ethyl benzene, which were significantly affected. The acetate levels increased, whereas the dimethyl trisulfide levels decreased during and after the intervention. For ethyl benzene only an effect during the synbiotic intervention period was observed. Conclusion: We report a detailed analysis of the influence of L. casei Shirota combined with oligofructose-enriched inulin on fermentation metabolites. Our results indicated a stimulation of saccharolytic fermentation and, importantly, a reduction of potentially toxic protein fermentation metabolites dimethyl trisulfide and ethyl benzene attended these effects.