Impact on diet quality

The main metric used to identify ultra-processed food consumption patterns is the percentage of ultra-processed food in diets, in calories or in grams. This information has been published using data from national surveys in several countries^{(Reference Juul, Parekh and Martinez-Steele8–Reference Liu, Steele and Li17)}. There is a large variation of ultra-processed food consumption between countries, from less than 16 % of the total energy in Colombia^{(Reference Parra, Da Costa-Louzada and Moubarac14)} up to 57 and 58 % in the UK and USA, respectively^{(Reference Rauber, Louzada and Steele15,Reference Martínez Steele, Popkin and Swinburn18)} .

There are some publications regarding ultra-processed trends. Brazil^{(Reference Levy, Andrade and da Cruz16)} and Mexico^{(Reference Marrón-Ponce, Tolentino-Mayo and Hernández-F12)}, for instance, have a long series of budget surveys. These countries had a low-ultra-processed food consumption in the 1980s and 1990s and now they are both close to 20 % of the total energy. In Mexico, the ultra-processed food consumption increased from 10 % in 1984 up to 23 % in 2016^{(Reference Marrón-Ponce, Tolentino-Mayo and Hernández-F12)}. In Brazil, the consumption of ultra-processed foods was 10 % of the total energy of diets in 1987–1988 and it reached 21 % in 2018. In high-income countries such as Canada^{(Reference Moubarac, Batal and Martins19)} and Spain^{(Reference Latasa, Louzada and Martinez Steele20)}, these publications show a solid increase over time in Canada^{(Reference Moubarac, Batal and Martins19)}, from 24 % in 1939 to 55 % in 2001. And a very large increase, from 10 to almost 30 % in 20 years, in Spain^{(Reference Latasa, Louzada and Martinez Steele20)}.

In the USA, consumption is very high, and reached 67 % of the total energy in children in 2017–2018^{(Reference Juul, Parekh and Martinez-Steele8,Reference Wang, Martínez Steele and Du21)} . In the UK, data from the period 2008–2019 show a decrease in consumption of soft drinks, sausages and margarine, but an increase in biscuits, salty snacks and ready-to-eat meals^{(Reference Madruga, Steele and Reynolds22)}. Overall, ultra-processed foods intake is about 56 % of total energy^{(Reference Madruga, Steele and Reynolds22)}.

Data from Euromonitor, the world's leading provider of strategic market research reporting, show that ultra-processed foods and drinks sales are growing almost everywhere. During the period 2006–2019, in Australasia and North America, and Western Europe sales of ultra-processed foods increased from 128 kg/per capita to 134 kg/per capita and from 106 kg/per capita to 115 kg/per capita, respectively. There are regions where ultra-processed sales are still comparatively low, such as Africa and Asia. Regions with lower consumption show a higher increase rate^{(Reference Baker, Machado and Santos23)}.

A systematic review of the impact of ultra-processed food on diet quality, including a meta-analysis, with data from 13 countries, shows that an increase in consumption of ultra-processed foods is associated with a decline of the overall dietary nutrient profile^{(Reference Martini, Godos and Bonaccio24)}. The higher the ultra-processed food intake, the higher the energy intake, and that of saturated fats and free sugars, and the lower the intake of fibre, protein and potassium^{(Reference Martini, Godos and Bonaccio24)}. Also, the higher the ultra-processed foods consumption, the lower the consumption of vegetables and fruits^{(Reference Martini, Godos and Bonaccio24)}.

Impact on diseases

Investigations from many countries link high ultra-processed food consumption with greater risk of disorders, diseases and premature death. Cohort studies have found links with obesity and adiposity outcomes, type 2 diabetes, hypertension, dyslipidaemia, hyperuricaemia, CVD, breast, ovarian, brain and overall cancer, non-alcoholic cirrhosis, Crohn's disease, chronic renal failure, depression, cognitive decline, dementia and all-cause mortality^{(Reference Moradi, Entezari and Mohammadi25–Reference Zhang, Gan and Ye39)}.

These are reinforced by at least forty-one prospective studies, and eleven systematic reviews and meta-analyses. For adiposity, a recent meta-analysis comparing the highest and lowest consumption quartile of ultra-processed food was 1⋅55 for obesity, 1⋅36 for overweight and 1⋅41 for abdominal obesity^{(Reference Moradi, Entezari and Mohammadi25)}. For this outcome, as well as prospective studies and systematic reviews with meta-analyses^{(Reference Moradi, Entezari and Mohammadi25)}, there is a randomised clinical trial^{(Reference Hall, Ayuketah and Brychta40)}.

Twenty adults were confined at a clinical centre, randomised into two groups, to consume, ad libitum, either an ultra-processed food diet or a non-ultra-processed food diet for 2 weeks. They exchanged their diets after this period. Both groups had meals which contained the same amount of energy, macronutrients, sugar, sodium and fibre. When participants were on the ultra-processed food diet, they ate about 500 calories more every day, in relation to the day they were on the non-ultra-processed diet. They gained an average of almost 1 kg after the week they were on the ultra-processed food diet and lost the same amount after the week they were on the unprocessed food diet. This showed that high ultra-processed food diets cause higher energy intake and weight gain^{(Reference Hall, Ayuketah and Brychta40)}.

Type 2 diabetes has been investigated by prospective cohort studies in France^{(Reference Srour, Fezeu and Kesse-Guyot41)}, UK^{(Reference Levy, Rauber and Chang42)}, Spain^{(Reference Llavero-Valero, Escalada-San Martín and Martínez-González43)} and the Netherlands^{(Reference Duan, Vinke and Navis44)}. Meta-analysis found that each 10 % increase in ultra-processed food intake (kJ/day) was associated with a 15 % higher risk of type 2 diabetes^{(Reference Moradi, Kermani and Bagheri37)}.

A meta-analysis published in 2022 using nine observational studies showed that a higher ultra-processed food consumption increased by 23 % the risk of hypertension, comparing highest and lowest categories of ultra-processed foods consumption^{(Reference Wang, Du and Huang38)}.

For CVD, a meta-analysis evaluated the association between ultra-processed food and CVD incidence and mortality. A higher intake of ultra-processed food was associated with a 29 % increased risk of CVD incidence and mortality and a 34 % increased risk of cerebrovascular disease incidence and mortality^{(Reference Pagliai, Dinu and Madarena27)}.

Ultra-processed food has been associated with all-cause mortality in prospective cohorts conducted in the USA, Spain, France and Italy. Meta-analysis showed that ultra-processed foods consumption increased all-cause mortality by 21 % comparing highest and lowest categories of ultra-processed foods consumption^{(Reference Suksatan, Moradi and Naeini36)}.

Reasons for harm

There are many reasons why ultra-processed foods are problematic. Usually, they are convenient, practical and portable, generally designed to be consumed anywhere – in front of television or a computer, in the workplace or walking or driving –, and dispense with the use of plates and cutlery^{(Reference Monteiro, Cannon and Levy7)}. Most of the time, they are sold as snacks, drinks or ready-to-eat or ready-to-heat meals. So, they displace freshly prepared meals based on natural or minimally processed foods. Some studies showed that portion sizes as served in fast-food outlets have increased significantly in recent decades^{(Reference Piernas and Popkin45)} and a direct association of bigger portions with total energy intake and weight gain was found^{(Reference Steenhuis and Vermeer46,Reference Albar, Alwan and Evans47)} .

The set of these unfavourable extrinsic characteristics of ultra-processed foods is further amplified by aggressive and sophisticated marketing. It changes social norms, especially among the most vulnerable consumers, such as children^{(Reference Mallarino, Gómez and González-Zapata48)}. Many marketing strategies for these products rely on unsubstantiated health claims. In low- and middle-income countries, advertising quickly penetrates emerging markets^{(Reference Lobstein, Jackson-Leach and Moodie49)}.

Also, there are various plausible biological reasons why ultra-processed foods increase the risk of disease. One is the negative impact of the consumption of ultra-processed foods on diet quality^{(Reference Martini, Godos and Bonaccio24)}. Although, studies adjusted for intake of total fat, sugar and sodium^{(Reference Moradi, Entezari and Mohammadi25)} still show associations with disorders and diseases, so other characteristics of ultra-processed foods besides dietary profile are evidently harmful to health.

Thus, evidence showed that consumption of large amounts of ultra-processed foods lead to lower water intake^{(Reference Marchese, Livingstone and Woods50)} and higher intake of food additives^{(Reference Dunford, Miles and Popkin51)}. Some additives such as artificial sweeteners, emulsifiers and colourings, evidently harm gut microbiota^{(Reference Zinöcker and Lindseth52)}. Furthermore, additives combined with fat, salt and sugar create hyperpalatable foods which may be addictive and so consumed excessively^{(Reference Monteiro, Cannon and Levy7)}.

In addition, ultra-processing damages or destroys the whole food structure (its matrix). This evidently adversely affects food absorption and bioaccessibility and inflames gut microbiota^{(Reference Zinöcker and Lindseth52)}. It also destroys the phytochemicals in food^{(Reference Steele and Monteiro53)}.

The packages of ultra-processed food contain plastic molecules, such as phytates and bisphenols^{(Reference Buckley, Kim and Wong54)}. A study identified that bisphenol A promotes insulin resistance and oxidative stress^{(Reference Zhang, Huang and Zhuang55)}. Also, processing using intense heat and extrusion can create acrolein and acrylamide that have been linked to oxidative stress and insulin resistance^{(Reference Zhang, Huang and Zhuang55)}.

Other factors, such as increased glycaemic response, reduced satiety and thermic effect^{(Reference Fardet56)}, also plausibly explain why ultra-processed foods increase the risk of various disorders and diseases and premature death.

Public policies and actions

Public health policies and actions designed to reduce consumption of ultra-processed food, or else of fatty, sugary and/or salty foods that are usually ultra-processed, are in place in a number of countries⁽⁵⁷⁾.

The ‘golden rule’ of the official Brazilian dietary guidelines is ‘Always prefer natural or minimally processed foods and freshly made dishes and meals to ultra-processed foods’⁽⁶⁾. These guidelines also consider the cultural, social and environmental aspects involved in food choices.

In Brazil, the National School Feeding Program offers free school meals to all students in public schools (primary, middle and high school). It regulates processed and ultra-processed food to a maximum of 20 % of the total budgets, prohibits ultra-processed foods in any form to children up to 3 years of age and also prohibits soft drinks, chocolate, candies, cookies, cakes with toppings or fillings and powdered food to all children⁽⁵⁸⁾.

Other countries have recommended less ultra-processed food or less food that is in effect ultra-processed in their official guidelines. These include France, Israel, Chile, Uruguay and Ecuador^(59–63).

The Pan-American Health Organization Nutritional Profile Model recommends front-of-package warning labels on processed and ultra-processed foods with high amounts of sugar, sweeteners, fat and/or sodium. It also recommends fiscal policies and restriction of sales and advertising⁽⁶⁴⁾. Chile, Mexico, Uruguay, Peru, Brazil and Ecuador have implemented front-of-package labels warning of high content of sugar, saturated fat and sodium^{(58,65–Reference Reyes, Garmendia and Olivares69)} . In Mexico, the labels also warn about non-nutrient components, such as sweeteners⁽⁶⁵⁾. Chile has also regulated marketing on food packaging. Products with warning labels cannot carry promotional strategies such as cartoon characters^{(Reference Reyes, Garmendia and Olivares69)}.

In Brazil, food corporations have impeded regulation^{(Reference Mialon and Da Silva Gomes70–Reference Pereira, Gomes and Carvalho73)}. The current Brazilian front-of-package labels include only added sugar, saturated fat and sodium with more flexible cut-off points, and use a warning in the form of a magnifying glass, in reduced size compared to other Latin American countries^{(Reference Mialon and Da Silva Gomes70)}.

Various countries restrict advertising of poor nutritional quality products during children's programmes and/or during programmes with a high audience of children and adolescents^(74–76). More general policies have so far only been established in Portugal, where the advertising of products with poor nutritional quality on websites, social networks and mobile applications for children under sixteen is forbidden⁽⁷⁷⁾.

Fiscal policies are implemented in some countries. Currently more than forty countries have taxed sugary drinks⁽⁷⁸⁾, which has reduced their consumption. In Chile and Mexico, fiscal policies implemented with other measures (such as marketing regulation and front-of-package warning labels) decreased the sales of sugary drinks by 24 and 7⋅6 % in 2 years, respectively^{(Reference Taillie, Reyes and Colchero79,Reference Arantxa Cochero, Rivera-Dommarco and Popkin80)} .

So far, few public policies have been directed specifically at ultra-processed food, and worldwide their production, sales and consumption continue to increase^{(Reference Baker, Machado and Santos23,Reference Vandevijvere, Jaacks and Monteiro81)} . The biggest obstacle to public policies and actions to reduce the consumption of ultra-processed foods is corporate influence on policy decision-taking and implementation^{(Reference Mialon and Da Silva Gomes70–Reference Mialon, Cediel and Jaime72)}. This strategy includes lobbying policy makers; stressing the economic importance of corporations; promoting deregulation; shaping the evidence on diet and health; financial incentives and establishing relationships with the media. Corporate interests' conflict with those of public health, and corporate representatives should be excluded from policy discussions and decisions^{(Reference Mialon and Da Silva Gomes70)}.