Corrections and clarifications

Claims made in the ‘appraisal’ are here shown in italics. Our response follows.

Gibney et al.’s claim fails to understand NOVA criteria. The NOVA classification is based on the nature, purpose and extent of food processing, as described in detail in their reference number 60⁽ Reference Gibney, Forde and Mullally ^{3 )}. It is not based on macronutrient content, although ultra-processed foods are indeed strongly associated with dietary macronutrient imbalances. Additionally, the fact that ultra-processed foods are associated with macronutrient imbalances obviously does not imply that their consumption only affects diseases related to energy intake.

The authors are unfamiliar with the NOVA literature. This claim refers to just two of the relevant studies. Most studies that use NOVA to assess the impact of ultra-processed foods on diet quality extend beyond sugar and micronutrients. For instance, studies conducted in Brazil⁽ Reference Louzada, Martins and Canella ^{4 ,} Reference Louzada, Martins and Canella ^{5 )}, the USA⁽ Reference Martinez Steele, Baraldi and Louzada ^{6 ,} Reference Martinez Steele, Popkin and Swinburn ^{7 )} and Canada⁽ Reference Moubarac, Batal and Louzada ^{8 )} show that as well as increasing added sugar and decreasing micronutrients, the more ultra-processed foods consumed, the greater the energy density of the overall diet and total energy intake, the greater the content of unhealthy fats, and the lower the content of protein and dietary fibre.

This claim also fails to understand the criteria. Added sugars are contained in ultra-processed foods, but also in two other NOVA categories: processed culinary ingredients (as table sugar) and many processed foods (as for example fruits in syrup)⁽ Reference Monteiro, Cannon and Moubarac ^{1 )}.

This misstatement is based on shifting the focus from ‘ultra-processed’ to ‘processed’ foods. Practically all food is processed in some sense and in some way. The term ‘processing’ is very general and not helpful. Judgements on food processing as such have little or no meaning, as NOVA authors have constantly repeated⁽ Reference Monteiro, Cannon and Moubarac ^{1 ,} Reference Monteiro ^{9 ,} Reference Moodie, Stuckler and Monteiro ^{10 )}. Food scientists and technologists and food manufacturers rightly emphasize the benefits of originally ancient as well as some relatively novel processes such as drying, non-alcoholic fermentation, chilling and freezing, pasteurization and vacuum-packing. The NOVA classification makes distinctions between types, uses and effects of food processing. Definitions need to be meaningful, detailed and objective in order to move research away from vague language such as ‘food processing’ and towards terminology that is specific, coherent, clear, comprehensive and workable. This is what NOVA does⁽ Reference Monteiro, Cannon and Moubarac ^{1 )}.

In fact, all studies except the one cited in the ‘appraisal’ show associations of ultra-processed foods with negative health effects. Gibney et al. also fail to acknowledge two papers from a large well-controlled cohort study that show a clear dose–response between consumption of ultra-processed foods and 9-year incidence of obesity⁽ Reference Mendonça, Pimenta and Gea ^{11 )} and of hypertension⁽ Reference Mendonça, Lopes and Pimenta ^{12 )} – the paper on obesity being published in 2016 in AJCN. The claim that only the UK cross-sectional study corrected for known confounders is also incorrect and misleading.

In fact, it is obviously possible, as demonstrated by the official national guidelines issued by the Ministry of Health of Brazil in 2014^{( 13 )}, the product of an extensive consultation with nutrition professionals from all regions and states, and then a further public consultation⁽ Reference Monteiro, Cannon and Moubarac ^{14 )}. Based on a thorough review of national dietary guidelines, the FAO identifies Brazil as one of the four forward-thinking countries whose governments are now taking the lead in developing healthy and sustainable national dietary guidelines^{( 15 )}. The recent official national dietary guidelines for Uruguay^{( 16 )}, a country with innovative and efficient public health policies including on tobacco control^{( 17 )}, are also based on the NOVA system.

Again, a lack of understanding of NOVA criteria. Processed packaged foods are not a proxy for ultra-processed foods. Processed packaged foods may be minimally processed foods (such as flour), processed culinary ingredients (such as vegetable oils) and processed foods (such as vegetables in brine), as well as ultra-processed foods. Further, this claim is contradicted by a report published by the Pan American Health Organization (their reference number 2) on annual sales of (correctly defined) ultra-processed products in thirteen Latin American countries. The report concludes: ‘The markets of several ultra-processed products are oligopolistic, dominated by transnational corporations. The market for two leading types of ultra-processed products – carbonated soft drinks and sweet or savory snacks – is highly concentrated, with more than two thirds of all sales captured by two companies’^{( 18 )}. The reference that the authors provide to support their claim ‘that the dominant suppliers of packaged, and thus mainly processed, foods are, in fact, small-to medium-sized enterprises’, their reference number 52, is a paper on food addiction.

The above claims are examples of factual and conceptual errors in the ‘appraisal’. Following are statements that reflect differences in values and matters of judgement.

NOVA is simple, in that it places every foodstuff into one of four groups, but it is not crude. Rather than grouping foods according to the main nutrients they provide, foods are grouped according to the nature, purpose and extent of food processing, meticulously set out in the paper cited as Gibney et al.’s reference number 60⁽ Reference Monteiro, Cannon and Moubarac ^{1 )}. But perhaps more important than level of complexity is whether the system of categorization works to predict the nutritional quality of diets and risk of disease. The evidence to date suggests that it does⁽ Reference Monteiro, Cannon and Moubarac ^{1 )}.

Where the cost of ultra-processed foods is generally lower than the cost of other food items, such as in the UK⁽ Reference Moubarac, Claro and Baraldi ^{19 )}, eating well is more expensive. Given known associations of ultra-processed foods with poorer nutrient adequacy, a more salient ethical issue is the affordability and achievability of healthy meals. Fiscal policies that combine taxation on ultra-processed foods with subsidies on whole or minimally processed foods can and should be used, as well as policies and programmes that alleviate poverty. Lack of knowledge of cooking, absence of proper kitchens and time pressures also all impede healthy eating. Where ultra-processed foods cost more, however, such as in Brazil⁽ Reference Moubarac, Claro and Baraldi ^{19 )}, eating well costs less, and displacement of freshly prepared meals by ready-to-consume ultra-processed foods, including those now being reformulated, is the ethical issue.

While we do state that ‘From the point of view of human health, at present, the most salient division of foods and drinks is in terms of their type, degree and purpose of processing’⁽ Reference Monteiro ^{9 )}, the NOVA approach to food classification does not overlook differences in nutrient composition between foods that belong to a same NOVA food group. Actually, the NOVA approach is necessary to make meaningful the division of foods according to their content of specific nutrients, as it can be seen in the new nutrient profile model developed by the Pan American Health Organization^{( 20 )}. The NOVA approach is a crucial development for a number of reasons. One is that it identifies ultra-processed foods. This is the food group consistently shown to be mainly responsible for currently common population dietary nutrient imbalances such as excessive intakes of total energy, added sugars and unhealthy fats, and the low intakes of dietary fibre, micronutrients and other bioactive compounds⁽ Reference Monteiro, Cannon and Moubarac ^{1 ,} Reference Martínez Steele and Monteiro ^{21 ,} Reference Julia, Martinez and Allès ^{22 )}. NOVA also identifies precisely the group of whole or minimally processed foods that, in great variety and mostly from plant sources, are the foundation for healthy and sustainable diets⁽ Reference Mozaffarian and Ludwig ^{23 ,} Reference Katz and Meller ^{24 )}. Further, NOVA identifies two other food groups, processed culinary ingredients and processed foods, that in modest amounts turn whole or minimally processed foods into diversified, nutritionally balanced, culturally sound, delicious, freshly prepared dishes and meals⁽ Reference Monteiro, Cannon and Moubarac ^{14 )}. Use of NOVA in examination of population dietary data is in our view essential in shaping rational sustainable meal- and food-based dietary guidelines and subsequent policies and programmes needed to protect public health and to improve the food environment. On another note, the authors’ choice of the word ‘irresponsible’ is regrettable and unproductive in terms of advancing scientific discourse.

How to handle scientific controversy

A surprising observation about the ‘appraisal’ is the number of oversights that usually would not (and should not) escape peer review. One of the studies cited as supporting an association between ultra-processed foods and obesity (their reference 17) is a paper on famine in Somalia. Their reference 10 is repeated as reference 13 with incorrect authors. And as noted above, their second reference 52, cited to support the claim ‘that the dominant suppliers of packaged, and thus mainly processed, foods are, in fact, small-to medium-sized enterprises’, is a paper on food addiction.

Also, while the conflicted interest of the lead author as a current consultant to Nestlé and to Cereal Partners Worldwide is acknowledged, the second author’s conflict of interest, his employment as a Senior Scientist at Nestlé’s Research Centre at Lausanne from April 2010 to October 2014 (https://sg.linkedin.com/in/ciaran-forde-0766995), was not mentioned. The fourth author has also consulted with a public relations firm (http://www.ucd.ie/foodandhealth/oldsite/people/academicstaff/dreileengibney/) whose current clients include McDonald’s (http://www.drurypn.ie/clients/), although this consultation was possibly not within the past three years specified in AJCN’s conflict of interest policy.

Such errors and oversights detract from the more important scientific questions that need to be asked in an emerging area of research.

A common practice followed by journal editors when considering a polemical contribution is to invite a full response in the same issue of the journal. However, no such invitation was made in the case of the ‘appraisal’. Challenges and debates are an essential part of the scientific endeavour, but AJCN provided no forum for this either as an invited response or as a letter, leaving Gibney et al.’s inaccurate claims and statements unchallenged in the journal.

The NOVA classification system challenges a much older and dominant system of classifying foods based on nutrient composition. Of course, it should be appraised. But scientific advances come from the exchange of well-reasoned and supported arguments, and from balanced debate. We invite further discourse on the topic of ultra-processed foods, for the sake of science and public health. We also respectfully suggest that all journals take on the responsibility of encouraging the informed and constructive exchange of ideas in controversial areas.