Ultra-processed food exposure and health outcomes: Current evidence, controversies, and future perspectives

Ultra-processed food (UPF) exposure has increased markedly worldwide and is now a major contributor to total energy intake in many countries. Evidence from large prospective cohort studies suggests that higher UPF exposure is associated with adverse health outcomes, including overweight and obesity, type 2 diabetes, cardiovascular disease, selected cancers, depression, and increased all-cause mortality. Short-term experimental studies further indicate that diets rich in UPFs can promote excess energy intake and weight gain, supporting biological plausibility. Several mechanisms have been proposed, including poor nutrient quality, high glycemic load, altered food structure and satiety signaling, exposure to additives and contaminants, gut microbiome perturbat ions, and displacement of minimally processed foods. Nevertheless, the field remains debated. Major controversies concern the Nova classification system, substantial heterogeneity within the UPF category, challenges in reproducible classification, and the extent to which observed associations reflect processing itself rather than nutrient profile, dietary patterns, or broader food environments. These issues hinder causal inference and sustain ongoing debate over whether UPFs act as independent etiological factors or function as markers of unhealthy diets. Policy responses vary internationally, ranging from explicit inclusion of UPFs in dietary guidelines to predominantly nutrient-based or hybrid frameworks. This narrative review summarizes current evidence l inking UPF exposure to health outcomes, critically examines methodological and conceptual limitations, and discusses implications for future research and public health policy.