The project goal is to support the development of functional food ingredients and products that are beneficial for the human gut & immune system and therefore of crucial importance for quality of life. The project will study the effects of specific non-digestible polysaccharides which have shown health potential in this field. The health effects of NPS will be focused around enhancing immune defence against pathogens, the reduction of infectious diseases like common cold and influenza of elderly and will make use of EFSA supported biomarkers that enable immune function claims and underpin the mechanism involved. The studied mechanisms are the innate and adaptive immune system and the possible involvement of the microbiota and microbiota-mediated products. To achieve this goal new and existing NPS will be studied for their health effects in a systematic way by developing a toolbox of dedicated assays and models that can be used by industry and authorities to study and approve food ingredients with a similar health focus. The project will: 1) perform biochemical analyses to study compounds, effect of processing and bioavailability, 2) develop standardized in vitro screening methods to be able to predict in vivo effects, 3) use dedicated in vivo and ex vivo analyses to study mechanisms of action and to validate biomarkers and 4) use and validate this knowledge in an intervention study. By combining the knowledge that will be gained from molecular, cellular and whole-organism studies, the goal will be to understand the bioactive mechanisms of these NPS and use this knowledge to design functional food products. SMEs make a very large contribution to the project, both as beneficiary of the products and as a technology service provider related to health research. This proposed project should provide the scientific basis for international nutritional organisations to recommend an immune-related functional health claim for some of the NPS studied.