The human gut microbiota has been recognized as a metabolically versatile digester playing an essential role in the regulation of the host metabolome. Non-digestible food components, in particular prebiotics, can modulate the microbial composition in the gut delivering health benefits to the host which may involve modulation of the immune system. The effect of non-digestible food components will be assessed in a human intervention study to find potential biomarkers and to generate novel hypotheses on gut and immune health. This study involves analysis on multiple levels (metabolomics, microbiome, immune modulators, transcriptomics) and in-vitro gut fermentation experiments. Metabolomic analysis (NMR/MS) will be applied on plasma, urine, faeces and in-vitro samples using state-of-the-art NMR- and MS-based profiling methods. Changes in these profiles will be assessed using multivariate statistical analysis, and these effects will be interpreted by pathway analysis.