This observational study aims to provide a comprehensive evaluation of dietary habits, physical activity, biomarkers involved in nutrition, metabolic and inflammatory status as well as intestinal permeability in apparently healthy volunteers aged over 18 years working or studying at the University of Milan. Furthermore, the analysis of the gut microbiota composition along with the omics approaches will be crucial for a better comprehension of the relationship between diet and health status in this population. As part of the OnFoods project (Project code PE00000003, Concession Decree No. 1550 of 11 October 2022 adopted by the Italian Ministry of University and Research, CUP D93C22000890001, Project title "ON Foods - Research and innovation network on food and nutrition Sustainability, Safety and Security - Working ON Foods"), the results will be valuable for suggesting targeted dietary and behavioral guidance in the context of public health policies.