Ultra-processed food
Ultra-processed foods are industrial formulations primarily composed of substances extracted from foods or synthesized in laboratories, containing little to no whole foods, and incorporating multiple ingredients including sugars, oils, salts, and additives such as emulsifiers, stabilizers, flavors, and colors not typically used in culinary preparations, designed through extensive processing to enhance palatability, shelf life, and convenience.[1] These products, exemplified by sodas, packaged snacks, instant noodles, and ready-to-eat meals, are distinguished in the NOVA classification system—developed by Brazilian researcher Carlos Monteiro and colleagues—as group 4, emphasizing the extent and purpose of industrial techniques like extrusion, molding, and hydrogenation that create hyper-palatable, energy-dense items low in fiber, protein, and micronutrients relative to unprocessed alternatives.[2][3] In contemporary diets, particularly in high-income nations, ultra-processed foods dominate consumption, accounting for approximately 58% of daily caloric intake in the United States and similar proportions elsewhere, displacing minimally processed whole foods and contributing disproportionately to added sugars, trans fats, and sodium.[4] This prevalence stems from their affordability, marketing, and engineering for rapid consumption, which exploits sensory and hedonic drives to promote overeating beyond physiological needs.[5] Randomized controlled trials demonstrate that ad libitum access to ultra-processed diets results in substantially higher energy intake—up to 500 kcal per day—and weight gain compared to iso-caloric minimally processed equivalents, attributing this to faster eating rates, reduced satiety signals, and amplified reward responses in the brain.[6][7] Epidemiological evidence consistently links higher ultra-processed food intake to elevated risks of obesity, cardiovascular diseases, type 2 diabetes, certain cancers, and premature mortality, with meta-analyses reporting dose-dependent associations even after adjusting for sociodemographics and lifestyle factors, though residual confounding from overall dietary patterns and reverse causation remain concerns in observational designs.[8][9] Experimental and mechanistic studies bolster causality by highlighting how their formulations disrupt homeostatic regulation, induce glycemic volatility, and foster addictive-like eating behaviors, yet debates persist over the NOVA system's emphasis on processing versus nutrient profiles, with critics arguing it overlooks healthful processed options and oversimplifies causal pathways beyond caloric surplus.[10][11][12]Definitions and Classifications
NOVA Classification System
The NOVA classification system, proposed in 2010 by Carlos Augusto Monteiro and colleagues at the University of São Paulo's Center for Epidemiological Research in Nutrition and Health Statistics (NUPENS), categorizes foods and beverages into four groups based on the nature, extent, and purpose of industrial processing rather than nutrient content.[13][14] This framework emphasizes how processing alters food matrices, potentially affecting digestibility, nutrient bioavailability, and overall dietary quality, with the stated goal of informing public health policies on food environments.[2] NOVA has been incorporated into guidelines by organizations such as the World Health Organization and Food and Agriculture Organization, particularly for analyzing ultra-processed food consumption patterns in national diets.[3] Group 1: Unprocessed or minimally processed foods consist of natural products subjected to processes like cleaning, grinding, freezing, pasteurization, or vacuum-packing that do not involve added substances such as salt, sugar, oils, or preservatives. Examples include fresh fruits and vegetables, grains, legumes, fresh or frozen meats, poultry, fish, milk, plain yogurt, eggs, and plain tea or coffee. These foods retain their intrinsic nutritional properties and are intended for direct consumption or use in cooking with minimal alteration.[2][13] Group 2: Processed culinary ingredients are derived from Group 1 foods or nature through processes like pressing, refining, grinding, milling, or drying, yielding items such as oils, butter, lard, sugar, honey, salt, vinegar, maize flour, and starches. These are not consumed alone but added to Group 1 foods during cooking to enhance flavor, texture, or preservation in home or traditional settings, without forming standalone products.[2][13] Group 3: Processed foods result from combining Group 1 foods with Group 2 ingredients using methods like canning, bottling, fermenting, or baking, often for preservation or flavor enhancement while preserving recognizable food structures. Examples encompass canned or bottled vegetables and fruits with added salt or sugar, salted or sugared nuts, cured meats like bacon, cheeses, freshly made breads and biscuits without additives, and fish canned in oil. These differ from Group 4 by relying on traditional techniques and fewer industrial additives.[2][13] Group 4: Ultra-processed foods are industrial formulations made mostly or entirely from substances derived from foods or synthesized in laboratories, with little if any intact Group 1 foods; they typically contain five or more ingredients, including high-fructose corn syrup, hydrogenated oils, modified starches, hydrolyzed proteins, soy protein isolates, and additives like artificial flavors, colors, emulsifiers, humectants, soluble or chewing gum bases, and preservatives. Examples include carbonated soft drinks, packaged snacks, confectionery, mass-produced breads and buns, reconstituted meats, instant noodles, ready-to-heat meals, and infant formulas. The purpose of processing is to create hyper-palatable, convenient, and durable products that extend shelf life, encourage overconsumption through sensory manipulation, and often displace minimally processed alternatives in diets.[2][13][14] Classification relies on ingredient lists and manufacturing details rather than nutritional profiles, allowing application to packaged products via labels; for unpackaged items, it draws on known production methods. Studies applying NOVA, such as those using 24-hour dietary recalls, have demonstrated inter-rater reliability exceeding 90% when standardized protocols are followed.[15] The system posits that ultra-processed foods (Group 4) contribute disproportionately to energy intake in many populations, with global data from 2000–2018 showing their share in household food purchases rising from 10–20% in middle-income countries to over 50% in high-income nations like the United States and United Kingdom.[14][3]Alternative Frameworks
Several alternative classification systems for food processing have emerged to address perceived limitations in the NOVA framework, such as its qualitative nature, lack of explicit nutritional thresholds, and potential subjectivity in categorizing industrial formulations.[16] These systems vary in the number of categories, emphasis on processing techniques, inclusion of additives, and integration of nutritional quality, often drawing from epidemiological or policy-oriented research.[17] For instance, the EPIC system, developed for the European Prospective Investigation into Cancer and Nutrition cohort, divides foods into three groups: non-processed, moderately processed, and highly processed.[2] Highly processed foods under EPIC are defined as industrially prepared items requiring minimal domestic preparation, such as heating, and incorporate specific techniques like drying and hydrogenation, without explicit reference to additives or nutritional profiles.[16] The IFPRI system, from the International Food Policy Research Institute, uses three groups—unprocessed, primary processed, and highly processed—focusing on secondary industrial processing that renders foods edible and typically high in added sugar, fat, and salt.[17] Highly processed examples include pastries and soft drinks, with an emphasis on expected nutritional excesses but no quantitative cut-offs or detailed techniques.[16] Similarly, the UNC framework, originating from University of North Carolina research, employs four categories: unprocessed, basic processed, moderately processed, and highly processed, where the latter consists of multi-ingredient industrial mixtures no longer recognizable from their original sources, such as sugary drinks or ketchup.[17] This system prioritizes the extent of transformation over purpose, excluding nutritional metrics.[16] More specialized alternatives include the UP3 framework from the UnProcessed Pantry Project, which categorizes foods as unprocessed or ultra-processed based on the presence of artificial ingredients like sweeteners and preservatives, alongside high levels of salt, sugar, and fat with low nutrient density.[18] It targets practical interventions in food pantries but lacks specificity on processing techniques.[16] The Siga system offers a holistic-reductionist approach, subclassifying ultra-processed foods via markers of ultra-processing (MUPs), such as cosmetic additives, synthetic aromas, and drastic techniques like extrusion-cooking, while incorporating quantitative nutritional thresholds (e.g., >1.5 g salt/100 g).[16] This allows for nuanced subcategories based on health risks, distinguishing it from NOVA by explicitly linking processing to defined nutrient excesses.[19]| System | Number of Groups | Definition of Highly/Ultra-Processed Category | Key Features/Differences from NOVA |
|---|---|---|---|
| EPIC | 3 | Industrially prepared, minimal home prep; includes drying, hydrogenation | Specifies techniques; no additives or nutrition focus[16] |
| IFPRI | 3 | Secondary processed, edible form with high sugar/fat/salt | Non-quantitative nutrition; less emphasis on formulations[17] |
| UNC | 4 | Multi-ingredient mixtures, unrecognizable originals | Focus on transformation extent; no techniques or nutrition[17] |
| UP3 | 2 | Artificial ingredients, high salt/sugar/fat, low nutrients | Practical for interventions; additives explicit but vague techniques[18] |
| Siga | Variable (subcategories) | MUPs like additives/synthetics; extrusion etc.; nutritional cut-offs | Quantitative nutrition; more precise on risks and techniques[16] |
Criticisms and Methodological Limitations
Critics argue that the NOVA classification system's definitions for ultra-processed foods are subjective and prone to inconsistent application, as they rely on qualitative assessments of ingredients and processing techniques rather than standardized criteria, leading to variability in how foods are categorized across studies.[20][21] For instance, the system's emphasis on the presence of additives or industrial formulations overlooks nutritional fortification and reformulation efforts that can improve micronutrient profiles in processed products.[22] This approach has been faulted for failing to differentiate between nutritionally equivalent foods based solely on processing extent, potentially stigmatizing items like fortified cereals or plant-based alternatives without empirical evidence of inherent harm from processing itself.[23] Reproducibility challenges further undermine NOVA's validity, with inter-rater reliability varying significantly when classifying complex food products, such as those with multiple reformulated ingredients or regional variations.[21] Validation studies have shown moderate agreement in dietary recall applications but highlight difficulties in operationalizing the system's guidelines for real-world databases, where ingredient lists may not fully capture manufacturing intent.[20] Moreover, NOVA's binary framing—grouping all ultra-processed foods together—disregards intra-category nutritional diversity, as evidenced by analyses revealing both nutrient-poor and fortified examples within the same group, complicating causal inferences about processing per se.[22][24] Epidemiological studies linking ultra-processed food intake to adverse outcomes, primarily observational, face methodological limitations including residual confounding from socioeconomic status, dietary reporting biases, and unmeasured lifestyle factors.[10] E-value analyses indicate that unaccounted confounders, such as overall energy intake or physical activity, could fully explain observed associations with weight gain, as the required strength of such confounders exceeds typical measured covariates.[25][10] Reverse causation may also play a role, where individuals with poorer health seek convenient ultra-processed options, inflating prospective risk estimates without randomized controlled trial evidence to establish temporality.[20] While meta-analyses report consistent correlations with cardiometabolic risks, the predominance of cohort designs limits causal claims, particularly given confounding by overall diet quality and access to fresh foods.[9][8]Historical Development
Origins in Food Processing Research
Research into food processing originated in the 19th century with innovations like Nicolas Appert's canning in 1809 and Louis Pasteur's pasteurization in the 1860s, aimed at extending shelf life and ensuring safety through empirical testing of heat treatments and preservation methods.[26] By the early 20th century, studies shifted toward nutritional impacts, such as vitamin retention during canning and drying, with researchers like Sherman and Hawley in the 1920s quantifying nutrient losses in processed versus fresh foods, establishing that minimal processing preserved bioavailability while excessive heat or refinement degraded it.[26] These efforts, often funded by governments and industry, prioritized causal mechanisms like enzymatic degradation and microbial inactivation over palatability enhancements, reflecting a first-principles focus on biochemical stability rather than consumer convenience.[27] Post-World War II industrialization accelerated processing research, driven by military logistics and civilian demand for ready-to-eat products, leading to fortified cereals and dehydrated meals analyzed for caloric density and macronutrient profiles.[28] By the 1970s, epidemiological data linked refined and additive-laden foods to rising obesity and cardiovascular risks, prompting critiques of "junk foods" in studies like those from the U.S. Senate Select Committee on Nutrition (1977), which highlighted empty calories from highly processed items despite their technological sophistication.[29] The term "ultra-processed" emerged in the 1980s to describe energy-dense snacks and convenience foods engineered with emulsifiers, flavors, and stabilizers, as noted in early nutritional epidemiology distinguishing them from traditionally processed staples by their industrial formulation intent.[30] The modern conceptualization crystallized in 2009 when Brazilian epidemiologist Carlos Monteiro and colleagues at the University of São Paulo proposed the NOVA classification in a Public Health Nutrition commentary, categorizing foods by processing extent and purpose to reveal how ultra-processed products—defined as industrially formulated mixtures of substances extracted or derived from foods, often with additives like hydrogenated oils and high-fructose corn syrup—promote overconsumption via hyper-palatability and displace nutrient-dense alternatives.[14] This framework arose from longitudinal dietary surveys in Brazil since the late 1980s, which documented a shift from minimally processed staples to ultra-processed items correlating with non-communicable disease surges, challenging nutrient-centric paradigms by emphasizing processing's causal role in metabolic disruption.[31] Unlike prior research focused on isolated additives, NOVA integrated processing as a holistic driver, validated through subsequent cohort studies showing ultra-processed foods comprising up to 58% of U.S. caloric intake by 2010 with independent health risks.[14][32]Adoption and Global Spread
The adoption of ultra-processed foods originated in the late 19th and early 20th centuries in the United States and Europe, with pioneering products such as Coca-Cola in 1886, Jell-O in 1897, Crisco shortening in 1911, and Kraft Mac & Cheese in the 1930s, which relied on novel industrial formulations, emulsifiers, and preservatives to create shelf-stable, ready-to-eat items.[33] These early innovations laid the groundwork for broader commercialization, but widespread adoption accelerated post-World War II, as wartime developments in dehydration, canning, and freezing technologies were repurposed for civilian markets, exemplified by Swanson's introduction of frozen TV dinners in 1954.[33][34] By the 1950s and 1960s, suburban expansion, rising female workforce participation, and marketing campaigns emphasizing time-saving convenience propelled these foods into households, transforming them from novelties to staples in high-income countries.[33][35] Key drivers included agricultural policy shifts and technological advancements that flooded markets with inexpensive commodities; for instance, U.S. corn and wheat production roughly doubled between 1970 and 1990, enabling the proliferation of high-fructose corn syrup—whose use increased over 1,000% by 1993—and other cheap fillers in snacks, sodas, and ready meals.[33] Food companies, including former tobacco firms like Philip Morris acquiring brands such as Kraft, intensified research and development, creating hyper-palatable products through additives for flavor, texture, and extended shelf life, while aggressive television advertising—often targeting children—further entrenched consumption.[33][36] In the United States, this era marked a shift where ultra-processed foods began comprising a majority of dietary energy by the late 20th century, rising to approximately 50-60% of adults' calories by the 2010s.[37] The global spread intensified from the 1980s onward, as multinational corporations expanded into middle- and low-income countries through modern retailing, supply chain investments, and tailored marketing, transitioning diets from traditional whole foods toward ultra-processed dominance.[37][36] This expansion was fueled by urbanization, rising incomes, and the establishment of supermarket chains in regions like Latin America and Asia, where ultra-processed foods grew from minor to 20-40% of caloric intake in many middle-income nations by the early 21st century, with the fastest market segment growth worldwide.[37] Examples include Nestlé's deployment of floating supermarkets along the Amazon River in 2010 to penetrate remote Brazilian markets, illustrating how corporations leveraged logistics and product adaptation to capture emerging consumer bases.[36] By the 2020s, ultra-processed foods accounted for over 50% of calories in high-income countries like the UK and Canada, mirroring U.S. patterns, while their proliferation in developing economies correlated with non-communicable disease rises amid minimal regulatory pushback.[37]Composition and Manufacturing
Key Ingredients and Additives
Ultra-processed foods are industrial formulations predominantly composed of ingredients derived from food substances or synthesized in laboratories, often in forms altered through extraction, fractionation, or chemical modification, resulting in products with minimal whole-food components.[38] These include refined sugars such as high-fructose corn syrup, which is produced via enzymatic isomerization of glucose from corn starch; hydrogenated or interesterified vegetable oils for texture and shelf stability; modified starches like maltodextrin for bulking and mouthfeel; and protein isolates such as soy or whey protein concentrate, obtained through hydrolysis and purification processes not feasible in domestic settings.[39] [2] Additives in ultra-processed foods encompass a broad array of substances designed to enhance palatability, appearance, stability, or convenience, many of which are exclusive to industrial manufacturing. Common categories include emulsifiers (e.g., mono- and diglycerides, lecithin) to prevent ingredient separation; stabilizers and thickeners (e.g., xanthan gum, carrageenan) for consistent texture; preservatives (e.g., sodium benzoate, sorbic acid) to inhibit microbial growth; and antioxidants (e.g., BHA, BHT) to prevent oxidation.[40] Sensory enhancers comprise artificial flavors and colors (e.g., tartrazine, allura red) to mimic natural attributes, alongside non-caloric sweeteners like aspartame or sucralose for low-calorie formulations.[2] These additives, often numbering in the dozens per product, enable the creation of hyper-palatable items but are rarely used in unprocessed or minimally processed foods.[3] The NOVA classification emphasizes that such ingredients and additives—totaling five or more per formulation in most cases—distinguish ultra-processed foods from simpler categories, prioritizing industrial functionality over nutritional density. For instance, a typical soft drink may contain high-fructose corn syrup, carbonated water, phosphoric acid, caffeine, and artificial flavors, none of which align with traditional culinary preparations.[14] This composition facilitates mass production but contributes to formulations high in energy density with low satiety value.[41]Industrial Production Techniques
Ultra-processed foods are manufactured through a series of industrial techniques that transform basic food substances into formulated products with extended shelf life, palatability, and convenience. These processes typically begin with the extraction and fractionation of whole foods into isolated components, such as sugars from corn via enzymatic hydrolysis to produce high-fructose corn syrup, or oils refined through degumming, neutralization, and bleaching.[38] Chemical modifications follow, including hydrogenation of vegetable oils to create solid fats stable for baking and frying, which alters fatty acid profiles to reduce unsaturation and improve texture.[5] [38] Assembly of these substances into final products employs high-intensity methods like extrusion cooking, where mixtures of flours, starches, and additives are subjected to high temperatures (up to 150–200°C) and pressures (10–30 bar) in a screw extruder, forcing the dough through a die for shaping and rapid expansion upon exit, as seen in the production of breakfast cereals, puffed snacks, and textured vegetable proteins.[42] [38] This technique gelatinizes starches, denatures proteins, and incorporates air for crispiness, often requiring pre-treatments like hydrolyzation to break down macromolecules. Molding and shaping via injection or compression are used for items like candies and bars, while pre-frying or deep-fat frying in industrial vats prepares products such as potato chips and extruded snacks, enhancing flavor through Maillard reactions and oil absorption.[42] For beverages and sauces, techniques involve high-shear mixing, homogenization, and pasteurization to emulsify oils, sugars, and flavorings into stable suspensions, with carbonation or aseptic filling extending shelf life without refrigeration.[38] Additives like emulsifiers (e.g., lecithin), stabilizers (e.g., gums), and synthetic flavors—derived from petrochemicals or enzymatic processes—are incorporated during these stages to mimic sensory qualities of unprocessed foods while preventing separation or spoilage.[38] These methods, reliant on proprietary equipment and formulations, distinguish ultra-processed foods from minimally processed items by prioritizing scalability and uniformity over preservation of natural structures.[42]Economic and Market Dynamics
Profitability for Producers
![Nestlé delivery truck promoting ultra-processed ice cream products][float-right] Ultra-processed foods offer significant profitability advantages to producers primarily through the utilization of low-cost industrial ingredients such as refined sugars, vegetable oils, and starches derived from subsidized commodities, which substantially reduce input costs compared to minimally processed alternatives.[43] These formulations enable mass production at scales unattainable with perishable whole foods, yielding production costs as low as $0.55 per 100 kcal for ultra-processed items versus $1.45 per 100 kcal for unprocessed foods.[44] Additionally, the incorporation of emulsifiers, preservatives, and stabilizers extends shelf life, minimizing spoilage losses and distribution expenses while facilitating global supply chains.[45] The engineered sensory properties of ultra-processed foods—achieved via precise combinations of salt, sugar, fats, and flavor enhancers—promote hyper-palatability, driving higher consumption volumes and repeat purchases that amplify revenue streams.[46] This consumer lock-in, coupled with aggressive marketing and branding, supports premium pricing relative to raw material costs, resulting in net profit margins for the global ultra-processed food sector that consistently exceeded those of broader food manufacturing between 1989 and 2019.[43] Major corporations have restructured operations to prioritize these high-margin products, with formulations optimized not for nutritional value but for financial returns, as evidenced by industry practices that favor cost-efficient additives over whole ingredients.[45] [47] Economies of scale further enhance profitability, as automated extrusion, hydrogenation, and other industrial techniques allow for high-volume output with minimal labor and variable costs, contrasting sharply with the labor-intensive handling required for fresh produce.[48] While critics argue this model externalizes health and environmental costs to society, producers benefit from reduced waste—UPF formulations often incorporate byproducts or surplus agricultural outputs—and resilient demand amid economic pressures, where affordability sustains market dominance.[49] Empirical data from sector analyses confirm that these dynamics have propelled ultra-processed foods to constitute a disproportionate share of corporate earnings in multinational conglomerates like Nestlé and Kellogg's.[50]Consumer Affordability and Accessibility
![Walmart store exterior representing accessibility of ultra-processed foods in budget retail chains]float-right Ultra-processed foods (UPFs) are typically more affordable on a per-calorie basis compared to minimally processed or whole foods, enabling their widespread adoption among consumers seeking cost-effective nutrition. A 2020 analysis of Brazilian household purchases found that diets with a higher caloric share of UPFs were significantly cheaper, with UPFs contributing to lower overall food expenditure per unit of energy.[51] This economic advantage stems from industrial-scale production, extended shelf life, and reliance on inexpensive ingredients like refined sugars, fats, and starches, which reduce costs relative to fresh produce or unprocessed meats. In the United States, UPFs dominate staple categories in budget-oriented supermarkets such as Walmart and Target, where their prevalence is 41-42% higher than in stores like Whole Foods emphasizing less processed options.[52] Accessibility of UPFs is enhanced by their ubiquity in mainstream retail environments, including convenience stores, discount chains, and urban food deserts, where alternatives may be scarce or pricier. Low-income households, facing food insecurity, exhibit higher UPF consumption, with adjusted intake reaching 55.7% of daily calories among those with very low food security compared to 52.6% in high-security groups, based on U.S. data from the National Health and Nutrition Examination Survey (NHANES).[53] This pattern persists across demographics, as UPFs comprise over half of at-home caloric intake in the U.S., with minimal variation by income—never falling below 47-49% even in higher earners—reflecting their entrenched availability.[54] Economic pressures, such as inflation, further drive reliance on durable, low-cost UPFs among the 18 million U.S. households experiencing food insecurity in 2023.[55] In global contexts, UPF affordability facilitates dietary shifts in low- and middle-income countries, where they often represent over 40% of purchased energy, exacerbating disparities as fresh foods remain relatively cost-prohibitive. Participation in nutrition assistance programs like SNAP correlates with elevated UPF intake, averaging median caloric shares influenced by program-eligible products' predominance in subsidized retail.[56] These dynamics underscore how UPFs' low price point and broad distribution prioritize caloric density over nutritional quality, particularly for vulnerable populations.Contributions to Food Security
Ultra-processed foods enhance food availability by leveraging industrial-scale production from high-yield, commodity crops like corn, wheat, and soy, which supports stable supplies amid fluctuating agricultural outputs and population growth pressures.[5] This scalability aligns with global demands, as processed formulations constitute a significant portion of household food purchases in both urban and rural settings, per FAO assessments of dietary shifts.[57] Their formulation with preservatives, emulsifiers, and packaging extends shelf life, minimizing spoilage during transport and storage, particularly in regions lacking robust infrastructure.[5] For example, processed fruit and vegetable products exhibit approximately 14% lower waste rates compared to fresh counterparts, aiding supply chain efficiency and reducing overall food loss.[58] Economic accessibility is bolstered by the low cost per calorie of many ultra-processed items, making them viable for low-income households facing caloric deficits.[59] In the United States, individuals with very low food security derive up to 55.7% of energy intake from such foods, reflecting their role in bridging immediate energy needs where fresh alternatives are pricier or less attainable.[53] Globally, this affordability facilitates year-round access in urbanizing areas with time constraints on home preparation, as processing techniques preserve sensory qualities while cutting distribution costs.[5] Certain formulations, such as fortified cereals or plant-based milks, further contribute by delivering micronutrients like iron and folate in convenient packages, supporting basic nutritional access in resource-limited contexts.[60] These attributes have underpinned expansions in food aid and emergency responses, where shelf-stable ultra-processed products enable rapid deployment without refrigeration, as seen in humanitarian distributions.[61] Nonetheless, while advancing caloric security, reliance on ultra-processed foods can strain nutritional security due to their frequent micronutrient deficiencies absent fortification, prompting calls for balanced integration with minimally processed options in policy frameworks.[5] Empirical data from dietary surveys indicate processed foods supply over 50% of key nutrients like dietary fiber (55%) and iron (64%) in some populations, underscoring their practical utility despite quality critiques.[60]Consumption Trends
Global and Regional Patterns
Ultra-processed foods (UPFs), as defined by the NOVA classification system, constitute a substantial portion of dietary energy intake globally, with consumption levels varying widely by region and socioeconomic context. In high-income countries, UPFs often account for over 50% of total caloric intake, reflecting heavy reliance on industrially formulated products high in sugars, fats, salts, and additives. Worldwide, UPF intake has surged in recent decades, approaching nearly half of average daily dietary energy in many populations by the mid-2020s, driven by urbanization, marketing, and convenience demands.[62] [59] In North America, consumption is among the highest, with the United States reporting UPFs comprising 58% of daily energy intake as of recent national surveys. Canada shows similar patterns, exceeding 50% in adult diets. Europe exhibits variability, averaging 25% of energy from UPFs across the continent, with lower shares in southern countries like Portugal and Italy (around 15-20%) compared to higher northern and western nations such as the United Kingdom (57%) and Norway (up to 40%).[59] [63] [64] In Latin America and the Caribbean, UPF intake ranges from lows of 16% in Colombia to higher levels in Mexico (30%) and Brazil (around 20-30%), with rapid increases noted since the 2000s due to expanding supermarket penetration and processed import growth. Asia and Africa display lower baseline consumption—e.g., 26-27% in parts of East Asia like China by 2016, and 39% in South Africa—but trends indicate acceleration, particularly in urbanizing middle-income areas where UPF sales have risen steadily. Oceania, including Australia (40%), mirrors high-income patterns akin to North America.[59] [64] [65] These patterns correlate with economic development: higher UPF shares in wealthier nations reflect mature food systems favoring shelf-stable, palatable products, while in low- and middle-income countries, consumption is climbing from lower bases amid dietary transitions away from traditional staples. Data from household purchase surveys underscore this, showing UPFs as 20-60% of expenditures in diverse settings, with global per capita UPF availability exceeding 100 kg annually in high-income contexts by the 2020s.[66] [67][68]Demographic Variations and Recent Data
Consumption of ultra-processed foods exhibits variations across demographic groups, with youth generally showing higher intake relative to adults. In the United States, from August 2021 to August 2023, youth aged 1–18 years derived 61.9% of their caloric intake from ultra-processed foods, compared to 53.0% for adults aged 19 years and older.[69] Among adults, intake decreases with age: those aged 19–39 years consumed 54.4% of calories from such foods, 40–59 years consumed 52.6%, and those 60 years and older consumed 51.7%.[69] Similar patterns hold for children and adolescents up to age 18, who obtained nearly 62% of calories from ultra-processed foods between 2021 and 2023.[70] Gender differences appear consistent across studies, with males often reporting higher consumption. A 2025 analysis in South Korea found men consumed significantly more ultra-processed foods than women, attributing this to dietary habits and preferences.[71] Likewise, a Brazilian study from the same year linked male gender positively to higher intake, independent of other factors like cooking skills.[72] In Canada, high early-childhood consumption correlated more strongly with obesity development in males than females in a 2025 cohort study.[73] Socioeconomic status influences intake variably by context. In the US, adults with family incomes at 130–349% of the federal poverty threshold consumed more ultra-processed foods than those below 130%, based on National Health and Nutrition Examination Survey (NHANES) data.[74] Conversely, in the UK, lower socioeconomic status adults exhibited higher consumption in a 2025 examination of influencing factors.[75] A 2024 Chinese study associated higher socioeconomic status with elevated ultra-processed food intake, suggesting access to convenience products drives this trend in some middle-income settings.[76] In Canada, 2015 data showed pervasive consumption across groups but highest among non-immigrants and those in higher urban density areas.[77] Ethnic and racial variations highlight disparities, particularly in immigrant and minority groups. Among US adults in 2025 data, non-Hispanic Whites reported the highest any-day consumption at 47.9%, while non-Hispanic Asians had the lowest at 35.5%; foreign-born adults showed rising intake trends aligning with native-born levels over time.[78] A 2025 Canadian study of Black children of African and Caribbean descent identified social determinants like acculturation and food environment as key drivers of intake in this subgroup.[79] Recent international data underscore regional differences. In South Asia, 2025 surveys reported ~75% of participants in Bangladesh, Sri Lanka, and North India consuming ultra-processed foods the previous day, versus 41% in South India and Pakistan, reflecting urbanization and market penetration.[80] European household availability ranged from 10.2% in Portugal to 50.4% in the UK as of recent assessments, with modest declines in some countries like France (2–15% over time) but increases in others like the UK (3–9%).[81][82] In the US, home-sourced ultra-processed food trends showed only minor shifts by demographics from 2001–2022, maintaining over 50% of calories in recent years.[54]| Demographic Group | Key Finding on UPF Consumption (% Calories or Prevalence) | Source Period |
|---|---|---|
| US Youth (1–18) | 61.9% of calories | 2021–2023 |
| US Adults (19+) | 53.0% of calories | 2021–2023 |
| Males (global) | Higher intake than females | 2025 |
| NH Whites (US) | 47.9% any-day consumption | 2025 |
| South Asia (high) | ~75% previous-day consumption | 2025 |
Health Associations and Evidence
Observational Studies on Risks
Numerous large-scale cohort studies and meta-analyses of observational data have linked higher consumption of ultra-processed foods (UPFs) to elevated risks of various adverse health outcomes, including obesity, cardiovascular disease, cancer, and all-cause mortality.[83] A 2020 systematic review and meta-analysis of 43 observational studies found that UPF consumption was associated with a 36% increased odds of overweight (OR: 1.36; 95% CI: 1.23-1.51) and a 55% increased odds of obesity (OR: 1.55; 95% CI: 1.36-1.77), based on data from over 500,000 participants across multiple countries.[84] These associations persisted after adjustments for total energy intake and socioeconomic factors, though residual confounding remains a potential limitation in observational designs.[84] In cardiovascular health, prospective cohorts such as the French NutriNet-Santé study and UK Biobank analyses have reported dose-response relationships, with a 10% increase in UPF dietary proportion linked to higher incidence of cardiovascular events (HR: 1.12; 95% CI: 1.05-1.20).[85] A 2024 meta-analysis of three prospective cohorts involving over 260,000 participants confirmed that higher UPF intake correlates with elevated cardiovascular disease risk, particularly from sugar-sweetened and artificially sweetened beverages as well as processed meats, while some UPF subgroups like ultra-processed whole grains showed inverse associations.[86] For mortality, a 2024 BMJ analysis of 115,384 UK adults followed for 9.1 years indicated that substituting 10% of UPFs with minimally processed foods could reduce all-cause mortality by 11% (HR: 0.89; 95% CI: 0.82-0.96), driven by non-cancer and non-cardiovascular causes.[87] Similarly, higher UPF exposure was tied to a 19% greater risk of cardiovascular mortality in a large European cohort.[88] Cancer risks have also been documented in observational data, with a 2023 meta-analysis of nine prospective studies showing a 10% increment in UPF consumption associated with a 13% higher overall cancer risk (HR: 1.13; 95% CI: 1.07-1.18) and 12% higher breast cancer risk (HR: 1.12; 95% CI: 1.05-1.20), based on over 260,000 participants and more than 6,300 cancer cases.[89] Mechanisms proposed include additives, high glycemic loads, and displaced nutrient-dense foods, though these studies adjusted for confounders like smoking and physical activity.[89] Additional associations include mental disorders, with UPF intake linked to depressive symptoms in cross-sectional and longitudinal data, and dementia in older adults (HR: 1.28 for highest vs. lowest quartile).[83][90] An umbrella review of 45 meta-analyses graded evidence as convincing for UPFs increasing risks of renal function decline and wheezing in youth.[91] While these findings from diverse populations—spanning Europe, North America, and Asia—suggest consistent patterns, observational studies cannot establish causality due to potential reverse causation, measurement errors in dietary assessment (e.g., food frequency questionnaires), and unmeasured confounders like overall diet quality.[92] Nonetheless, the magnitude and reproducibility of associations across studies underscore UPFs as a modifiable risk factor warranting further mechanistic investigation.[93]Interventional Trials and Causal Questions
Interventional trials, particularly randomized controlled trials (RCTs), provide stronger evidence for causal relationships than observational studies by controlling for confounders and manipulating ultra-processed food (UPF) exposure directly. However, such trials remain scarce due to logistical challenges, including the difficulty of sustaining controlled diets over extended periods, ensuring participant blinding, and applying consistent definitions like the NOVA classification for UPFs.[94][7] The few existing RCTs primarily examine short-term effects on energy intake and body weight under ad libitum conditions, highlighting mechanisms such as hyperpalatability, faster eating rates, and higher energy density that promote overconsumption.[95] A landmark inpatient RCT by Hall et al. in 2019 involved 20 weight-stable adults (mean BMI 27 kg/m²) who consumed either UPF or unprocessed diets ad libitum for 14 days each in a crossover design, with diets matched for macronutrients, sugar, fat, sodium, and fiber. Participants ingested 508 kcal/day more on the UPF diet (p=0.0001), leading to a 0.9 kg weight gain versus a 0.9 kg loss on the unprocessed diet (p=0.009). Eating rates were 17 kcal/min faster on UPFs (p<0.0001), suggesting sensory properties drive passive overeating independent of nutritional content.[95] This trial establishes causality for UPF-induced excess calorie intake and adiposity in controlled settings, though its inpatient nature limits generalizability to free-living scenarios.[96] More recent trials explore UPF within structured healthy eating patterns. The 2025 UPDATE RCT (n=50 completers, mean BMI 32.7 kg/m²) compared 8-week ad libitum UPF and minimally processed food (MPF) diets aligned with UK Eatwell Guide recommendations in a crossover design. Both reduced body weight (-1.05% for UPF vs. -2.06% for MPF; p=0.024), but MPF yielded greater fat mass loss and triglyceride reductions, while UPF lowered LDL cholesterol more. These findings indicate UPFs can support weight loss when calorie-controlled via guidelines but underperform MPF in body composition and some metabolic markers, raising questions about inherent processing effects beyond overconsumption.[7] Smaller RCTs reinforce overeating risks. A 2024 crossover trial in 9 overweight Japanese males found UPF consumption increased daily energy intake by 813 kcal (p=0.004) and body weight by 1.1 kg (p=0.021) over 14 days, linked to reduced chewing frequency. Evidence for causal links to non-weight outcomes like cardiovascular events or mortality remains absent from RCTs, relying instead on observational data prone to residual confounding. Critics argue NOVA's broad categorization conflates formulation effects with poor dietary quality, complicating isolation of causality; longer-term, larger trials are needed to assess sustained impacts and mechanisms like gut microbiota disruption or additive influences.[6][97]Specific Health Outcomes
Greater consumption of ultra-processed foods (UPFs) is associated with elevated risks of obesity, with systematic reviews indicating odds ratios ranging from 1.29 to 1.51 for obesity in adults, supported by interventional evidence where ad libitum UPF diets led to 500 excess kcal/day intake and 0.9 kg weight gain over two weeks compared to unprocessed diets.[98][99] This overconsumption is attributed to hyper-palatability, rapid digestion, and poor satiety, though confounding by overall diet quality persists in observational data.[8] Type 2 diabetes risk increases with UPF intake, with meta-analyses showing a 48% higher incidence (RR 1.48, 95% CI 1.32-1.66) for highest versus lowest consumers, linked mechanistically to glycemic load, insulin resistance, and adiposity from UPF-driven caloric surplus.[98][100] Cardiovascular outcomes include heightened hypertension (OR 1.37), dyslipidemia, and events like myocardial infarction, with each 10% UPF energy increase correlating to 12% greater CVD risk in prospective cohorts; interventional data reinforce via worsened lipid profiles and endothelial function.[8][101]  and site-specific risks, such as colorectal (HR 1.29) and breast cancer, potentially via inflammatory pathways, additives, and obesity mediation, though causality remains inferential absent direct trials.[8][102] All-cause mortality rises 15% (HR 1.15, 95% CI 1.09-1.21) and CVD mortality 50% (HR 1.50) with high UPF exposure, per dose-response meta-analyses of over 1 million participants.[103][104] Mental health effects include 48-53% increased odds of common disorders like depression and anxiety, with prospective data showing faster symptom progression; limited RCTs suggest UPF reduction improves mood via gut-brain axis modulation.[8] Additional outcomes involve renal decline (OR 1.25), frailty, and cognitive impairment in older adults, consistently observed in longitudinal studies adjusting for confounders like socioeconomic status.[105][106] While subgroup variations exist—e.g., inverse CVD links for certain grain-based UPFs—overall evidence from diverse cohorts underscores dose-dependent harms, bolstered by trials demonstrating reversible effects post-reduction.[101][7]Countervailing Benefits and Examples
Certain ultra-processed foods, through fortification, have demonstrated benefits in combating micronutrient deficiencies. For example, consumption of iron-fortified breakfast cereals for 12 weeks in iron-deficient women led to significant improvements in hemoglobin levels and iron status markers, as measured by serum ferritin and total iron-binding capacity.[107] Similarly, fortification of cereals with folic acid has contributed to a substantial reduction in neural tube defects, with population-level data showing declines of up to 50% in regions implementing mandatory fortification programs since the 1990s.[108] These interventions leverage industrial processing techniques to incorporate bioavailable vitamins and minerals, addressing gaps in diets reliant on staple grains where natural nutrient levels may be insufficient.[5] In contexts of food insecurity or limited access to fresh produce, select ultra-processed products serve as affordable vehicles for nutrient delivery, supporting nutrition security. Whole-grain fortified cereals and low-sugar yogurts, classified as ultra-processed due to additives like emulsifiers, provide fiber, protein, and added micronutrients such as B vitamins and calcium, which observational data associate with neutral or protective effects against cardiometabolic risks when consumed moderately.[5] For instance, these items have been linked to improved dietary compliance in time-constrained households, indirectly aiding adherence to nutrient-dense patterns by reducing preparation barriers.[109] Peer-reviewed analyses indicate that such fortified options can mitigate anemia in infants and children, with studies reporting reduced iron deficiency rates following regular intake of fortified infant cereals.[110] Examples of beneficial applications include ready-to-eat fortified meals in emergency nutrition programs, where ultra-processed formulations ensure stable, portable delivery of calories and micronutrients without requiring cooking infrastructure, as evidenced by their use in addressing acute malnutrition in resource-limited settings.[109] However, these advantages are context-specific and pertain to reformulated products prioritizing nutrient density over palatability enhancers; broader ultra-processed food intake remains associated with adverse outcomes in non-deficient populations.[5]Practical Identification
Label Analysis Methods
Label analysis for ultra-processed foods relies on the NOVA classification system, which identifies group 4 products—typically industrial formulations of food-derived or synthetic substances combined with additives to create hyper-palatable, durable items—by scrutinizing the ingredient list on packaging.[38] A key criterion is the presence of at least one substance characteristic of ultra-processing, such as ingredients rarely or never used in home cooking or additives aimed at enhancing appearance, texture, or flavor rather than nutritional value.[38] These elements often appear early or midway in the list (e.g., modified starches or protein isolates as base components), with cosmetic additives clustered toward the end.[38] Common indicators include food-derived isolates and derivatives like high-fructose corn syrup, hydrogenated or interesterified oils, hydrolysed proteins, soya protein isolate, gluten, casein, whey protein, mechanically separated meat, fructose, maltodextrin, dextrose, lactose, or isolated fibers (soluble or insoluble).[38] Additive classes signaling ultra-processing encompass flavors, flavor enhancers, colors, emulsifiers, emulsifying salts, artificial sweeteners, thickeners, and agents for anti-foaming, bulking, carbonating, foaming, gelling, or glazing.[38] Products with five or more ingredients, particularly those unrecognizable in traditional recipes (e.g., an industrial bread listing emulsifiers and colors alongside flour, versus a simple version with only flour, water, yeast, and salt), frequently qualify as ultra-processed.[38]| Category | Examples of Ultra-Processing Indicators |
|---|---|
| Isolated Substances | High-fructose corn syrup, maltodextrin, soya protein isolate, whey protein, mechanically separated meat[38] |
| Modified Fats and Oils | Hydrogenated oils, interesterified oils[38] |
| Cosmetic Additives | Flavors, colors, emulsifiers, thickeners, artificial sweeteners[38] |