Beyond their nutritional profile (i.e. content in sugar, salt, saturated fat, fiber…) the way industrial foods are processed, formulated and packaged plays a key role in the etiology of multiple chronic diseases, including cancer. By applying the NOVA classification to all foods and beverages consumed by the participants of the large-scale web-cohort NutriNet-Santé (n=182000, 2009-ongoing, France), we showed for the first time a link between the consumption of ultra-processed foods (UPF) and an increased incidence of various pathologies such as certain cancers (BMJ 2018), cardiovascular diseases (BMJ 2019), and diabetes (JAMA Int Med 2020). These results contributed to changing official dietary guidelines in France and in several countries. Since then, >100 prospective studies worldwide consistently observed associations between UPF and adverse health outcomes, with the highest density of proof so far for mortality, cardiometabolic and mental health and mounting evidence that still needs to be consolidated for cancer (Lancet 2025; BMJ 2023). In order to depict the characteristics and components of UPF involved and strengthen causality arguments, we launched the ERC-funded ADDITIVES project to study the health impacts of the cocktails of food additives ingested daily by millions of people. We quantified for the first time the exposure to the ≈330 food additives authorized in Europe and consumed by participants of the NutriNet-Santé cohort. We showed positive associations between exposure to multiple food additives (nitrites, artificial sweeteners, emulsifiers, preservatives, mixtures of these additives…) and increased incidence of several cancers, cardiovascular diseases, hypertension and type 2 diabetes (Int J Epidemiol 2022; Plos Medicine 2022; JAHA 2023; Plos Medicine 2022; BMJ 2022; Diabetes Care 2023; BMJ 2023; Plos Med 2024; Lancet Diabetes 2024; Plos Med 2025; BMJ 2025; Nature Communications 2025). These results directly contributed to the re-evaluation of several classes of food additives, e.g. nitrites by the French Food Safety Agency (ANSES) in 2022, and aspartame (now classified as “possibly carcinogenic”) by the International Agency for Research on Cancer (WHO-IARC) in 2024. Research is ongoing in the cohort regarding dyes, glutamate, and food additive mixtures in association with cancer and other chronic disease risk. We are currently investigating the profiles of exposure to UPF and food additives in association with blood biomarkers of inflammation, oxidative stress and metabolic perturbations, as well as gut microbiota composition and functioning. Close collaborations with experimental research teams of toxicologists and physiologists allows us to test the impact of real-life exposure to additives and their mixtures in the framework of in vivo/vitro experiments for a better understanding of causal mechanisms (Food Chem Toxicol 2024 and other articles in preparation). We are also launching a new research program to explore other factors and mechanisms of action of UPFs, in particular contaminants created during industrial food processing and/or coming from food packaging. Indeed, food contact chemicals (FCCs) are among the key potential explanations for deleterious health impacts of UPFs, which are generally pre-packaged and kept for weeks/months/years in their packaging and often warmed-up in it, fostering migration of FCCs into food (Globalization and Health 2024; Nature Medicine 2025).