Introduction
Ultra-processed foods, defined by the NOVA classification system, are industrially formulated ready-to-eat products, such as packaged snacks, soft drinks, instant noodles, and prepared meals. They are typically made from modified food substances and additives that improve taste, texture, appearance, and shelf life, with little or no whole food content. Global sales and consumption patterns suggest diets are becoming increasingly ultra-processed.
Although several meta-analyses have synthesized findings from original studies examining associations between ultra-processed food consumption and adverse health outcomes, no comprehensive umbrella review has yet provided a broad overview and assessment of the existing meta-analytic evidence.
Objective
This study evaluated meta-analytic evidence of associations between consumption of ultra-processed foods, as defined by the NOVA food classification system, and adverse health outcomes.
Method
The authors conducted a systematic umbrella review of existing meta-analyses. Data sources included MEDLINE, PsycINFO, Embase, and the Cochrane Database of Systematic Reviews, as well as searches of reference lists from 2009 to June 2023.
Results
Ultra-processed food consumption was directly associated with 32 adverse health parameters, including mortality, cancer, and mental, respiratory, cardiovascular, gastrointestinal, and metabolic outcomes. Convincing evidence linked higher intake with increased risks of cardiovascular disease mortality, type 2 diabetes, anxiety, and common mental health disorders. Highly suggestive evidence also linked higher intake with all-cause and heart disease mortality, depressive outcomes, adverse sleep outcomes, wheezing, and obesity.
Discussion
More research is needed to clarify how ultra-processed dietary patterns contribute to poor health and early death. Evidence suggests that ultra-processed foods differ from unprocessed or minimally processed foods through poorer nutrient profiles, displacement of healthier foods, and changes to food structure caused by intensive processing. Diets high in ultra-processed foods tend to contain more added sugars, saturated fat, sodium, and energy density, while providing less fibre, protein, micronutrients, and beneficial compounds from foods such as fruits, vegetables, legumes, nuts, and seeds. These nutrient-poor patterns may contribute to chronic disease through pathways including inflammation.
The health effects of ultra-processed foods may also reflect physical and chemical changes from industrial processing and not nutrient composition alone. Reconstitution of the food matrix can affect digestion, absorption, and satiety. Additives (e.g., non-sugar sweeteners, emulsifiers, colourants, nitrates/nitrites), processing by-products (e.g., acrylamide, industrial trans-fatty acids), and packaging-related contaminants (e.g., bisphenols, microplastics) have also been linked to adverse health outcomes, including chronic inflammatory disease.
Experimental evidence supports a causal link between ultra-processed diets, increased energy intake, and weight gain. Key drivers of excess consumption include beverage-based energy sources, higher energy density, faster eating rates, hyper-palatability, and persuasive marketing, such as eye-catching packaging and health-related claims.
Conclusions
This umbrella review found that higher ultra-processed food consumption is associated with increased risks of adverse health outcomes, with the strongest evidence for all-cause and cardiovascular disease mortality, common mental health disorders, overweight and obesity, and type 2 diabetes. Evidence remains limited for asthma, gastrointestinal health, some cancers, and intermediate cardiometabolic risk factors, highlighting the need for further research and public health initiatives to reduce ultra-processed food intake.
