The human exposome covers the totality of non-genetic exposures from conception throughout the life course. The Flemish exposome project, FLEXiGUT, combines the unique and complementary expertise in Flanders on dietary- and environment-related human biomarkers and biomonitoring, metabolomics, microbiome research and epidemiology to investigate the complex human exposome. This first large-scale Flemish Exposome study, will make use of biomonitoring and -omics based technologies on the available biological matrices of the Flemish Environage Birth and the Flemish Gut Microbiome cohorts. Associations between the acquired exposome metadata and chronic low-grade gut inflammation parameters and related diseases will be analysed using an integrated -omics approach. Our pioneering results will be validated through extension towards other international cohorts.