Ultra-processed foods, as defined by the Nova food classification system, have become a dominant feature of global dietary patterns. These foods, which include products such as packaged snacks, carbonated beverages, instant noodles, and ready-made meals, are characterised by their minimal use of whole foods and the reliance on chemically modified ingredients and additives to enhance taste, texture, and shelf life. Over recent decades, the global dietary sector has shifted dramatically, with ultra-processed foods increasingly replacing traditional, minimally processed diets.
What Are Ultra-Processed Foods?
The Nova food classification system categorises foods based on their degree of processing. Ultra-processed foods fall into the highest category and are defined as industrial formulations containing little to no whole foods. They rely heavily on ingredients such as refined sugars, oils, fats, protein isolates, and additives like flavourings, colourings, emulsifiers, and preservatives. These additives are designed to make the products more palatable, durable, and convenient, often at the expense of nutritional quality.
Examples of ultra-processed foods include sugary cereals, soft drinks, packaged snacks, reconstituted meat products, and ready-made frozen meals. Unlike minimally processed foods, which retain much of their natural composition, ultra-processed foods undergo extensive physical and chemical transformations, resulting in products that are often high in calories, sugar, salt, and unhealthy fats while being low in fibre, protein, and essential micronutrients.
Global Trends in Ultra-Processed Food Consumption
The consumption of ultra-processed foods has increased worldwide, but significant variations exist between regions and countries. In high-income nations like the United States and Australia, ultra-processed foods account for 42% to 58% of dietary energy intake, whereas in countries like Italy and South Korea, the proportion is as low as 10% to 25%.
In low- and middle-income countries, the trend is also concerning. Nations such as Colombia and Mexico report that ultra-processed foods contribute 16% to 30% of dietary energy. This rise is driven by factors such as urbanisation, changing lifestyles, aggressive marketing strategies, and the global expansion of multinational food corporations. These shifts are particularly rapid in densely populated low- and middle-income nations, where traditional diets are being replaced by industrialised food systems.
Nutritional Deficiencies and Health Risks
Ultra-processed foods are characterised by poor nutrient profiles. They tend to be energy-dense and high in added sugars, saturated fats, and sodium, while lacking essential nutrients such as dietary fibre, vitamins, and minerals. These nutrient deficiencies contribute to a range of health issues, including obesity, cardiovascular diseases, and type 2 diabetes.
Additionally, the displacement of nutrient-rich whole foods, such as fruits, vegetables, legumes, nuts, and seeds, exacerbates dietary imbalances. This reduction in the consumption of bioactive compounds like polyphenols and phytoestrogens further limits the protective effects of a balanced diet.
Health Outcomes
Emerging evidence links ultra-processed food consumption to a range of adverse health outcomes. Chronic conditions such as cardiovascular diseases, type 2 diabetes, obesity, and certain cancers are consistently associated with diets high in ultra-processed foods. Furthermore, these foods are implicated in mental health issues, respiratory problems, and gastrointestinal disorders.
Mechanistic research suggests that the detrimental health effects are not solely due to the nutrient profiles of these foods. Factors such as food additives, contaminants from packaging materials, and harmful by-products of industrial processing play significant roles. For example, additives like non-sugar sweeteners and emulsifiers have been linked to disruptions in gut microbiota, which in turn contribute to systemic inflammation and metabolic dysregulation.
Findings from an Umbrella Review
An umbrella review of 45 pooled analyses, encompassing nearly 9.9 million participants, provides robust evidence on the associations between ultra-processed food consumption and adverse health outcomes. The review identified seven key health parameters, including mortality, cancer, and metabolic, cardiovascular, respiratory, gastrointestinal, and mental health outcomes.
Of the pooled analyses, 71% demonstrated that higher consumption of ultra-processed foods was associated with an increased risk of adverse outcomes. Nine percent of these analyses provided convincing evidence, particularly for cardiovascular mortality, common mental disorders, and type 2 diabetes. However, variability in the quality of evidence was noted, with 29% of the analyses rated as weak or lacking evidence. This heterogeneity was attributed to inconsistencies in study designs, statistical imprecision, and variations in how ultra-processed food consumption was measured.
Despite these limitations, the umbrella review highlights the strong association between ultra-processed food consumption and negative health outcomes. The findings support calls for public health interventions to reduce dietary exposure to ultra-processed foods.
Mechanisms of Action
The mechanisms through which ultra-processed foods contribute to poor health are multifaceted and extend beyond their nutrient profiles.
Additives and Contaminants
Ultra-processed foods often contain additives such as artificial sweeteners, colourings, preservatives, and emulsifiers. These substances have been linked to adverse health effects, including disruptions to the gut microbiome, increased inflammation, and metabolic changes. Emerging evidence also highlights the potential “cocktail effects” of multiple additives, which may have greater health implications than single substances.
Contaminants from packaging materials, including bisphenols, phthalates, and microplastics, are another concern. These chemicals can migrate into food products and have been associated with endocrine disruption and other health risks.
Industrial Processing
The intensive processing of foods alters their physical structure and nutrient composition. For instance, dietary reconstitution, a process in which foods are broken down and reassembled, can affect digestion, nutrient absorption, and satiety. Additionally, industrial processing generates harmful by-products such as acrylamide, advanced glycation end products, and polycyclic aromatic hydrocarbons, which are linked to chronic inflammatory diseases.
Policy Implications and Public Health Strategies
Addressing the public health challenges posed by ultra-processed foods requires a multifaceted approach. Several countries, particularly in Latin America and the UK, have implemented measures to reduce ultra-processed food consumption. These include front-of-pack warning labels, taxes on sugar-sweetened beverages, restrictions on marketing, and school bans on ultra-processed products.
The World Health Organisation (WHO) and the International Agency for Research on Cancer (IARC) have endorsed strategies to limit the intake of high-risk components commonly found in ultra-processed foods, such as added sugars and non-sugar sweeteners. These recommendations are aligned with the Nova classification system, which has been recognised as a valuable tool for assessing food processing levels.
Despite these efforts, challenges remain. Barriers to accessing fresh, minimally processed foods, including cost, time constraints, and limited availability, must be addressed to ensure equitable dietary improvements. Public health campaigns should also focus on raising awareness about the risks of ultra-processed foods and promoting healthier alternatives.
Strengths and Limitations of Current Research
The umbrella review provides a comprehensive synthesis of existing evidence on ultra-processed food consumption and health outcomes. Its strengths lie in its rigorous methodology, including duplicate study selection and data extraction, and the use of evidence classification criteria and GRADE assessments to evaluate the quality of pooled analyses.
However, limitations inherent to observational studies, such as residual confounding and measurement biases, must be acknowledged. The variability in how ultra-processed food intake is assessed, ranging from dietary recalls to food frequency questionnaires, introduces potential inconsistencies. Additionally, the high-level nature of umbrella reviews means that specific confounder adjustments and sensitivity analyses were not considered.
Future research should focus on randomised controlled trials to establish causal links and explore the differential effects of subcategories of ultra-processed foods. Understanding these nuances is essential for refining dietary recommendations and public health strategies.
Conclusion
The growing body of evidence linking ultra-processed food consumption to adverse health outcomes highlights the urgent need for public health interventions. Ultra-processed foods, with their poor nutrient profiles and harmful additives, contribute to a wide range of chronic diseases and exacerbate dietary inequalities globally. Addressing this issue requires a combination of policy measures, consumer education, and systemic changes to food environments.
As the global dietary sector continues to evolve, prioritising minimally processed, nutrient-dense foods will be critical for improving population health. By addressing the systemic factors that drive ultra-processed food consumption, policymakers and public health advocates can mitigate the health risks associated with these products and promote sustainable, equitable dietary patterns for future generations.
Reference
Lane, M. M., Gamage, E., Du, S., Ashtree, D. N., McGuinness, A. J., Gauci, S., Baker, P., Lawrence, M., Rebholz, C. M., Srour, B., Touvier, M., Jacka, F. N., O’Neil, A., Segasby, T., & Marx, W. (2024). Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ (Clinical Research Ed.), 384, e077310. https://doi.org/10.1136/bmj-2023-077310