Human health

Redefining healthy diets?

A minor part of the Western adult population is still in optimal cardiometabolic health, while the prevalence of obesity is increasing despite dietary guidelines. Some argue that it may be wiser to ignore the guidelines when evidence in support is insufficient and based on potentially overstated claims. It cannot be excluded that some advice may even be counterproductive. Aggressive promotion of plant-based diets and restriction of red meat could have potential consequences for the nutrient security of vulnerable groups, whereas an increase in ultra-processed "alternatives" may come with health risks. A more holistic approach, with a renewed focus on adequate essential nutrition, is needed to redefine healthy diets. Additionally, efforts should be made to reduce the consumption of ultra-processed foods, which may be a primary modifiable target for preventing non-communicable diseases.

This subsection addresses the following four elements:

The current health crisis and the problem with nutritional advice
Too zealous adherence is not necessarily harmless
Nutritionism as an alibi for ultra-processing
Ways forward?

The current health crisis and the problem with nutritional advice

Many countries worldwide face significant challenges in achieving optimal health among their populations. Only about one on ten adults in the US is in a state of optimal cardiometabolic health while the majority of Americans are either overweight or obese. Similar health issues are observed in other Western countries, where a high percentage of older adults are abdominally obese, and many are at high cardiometabolic risk. Public health nutrition strategies, including dietary guidelines, have been criticized for being ineffective and lacking evidence and rigor. Nutritional epidemiology of chronic disease (NECD) has been accused of producing implausible conclusions and overstating evidence. Some argue that the current dietary guidelines should be ignored altogether due to insufficient evidence. Additionally, 'preventive' public health nutrition has been described as arrogant, aggressive, presumptuous, and overbearing in its approach.

Too zealous adherence is not necessarily harmless

Excessive adherence to (or overinterpretation of) certain nutritional guidelines may have unintended consequences, especially for vulnerable groups. It can lead to overly restrictive diets, particularly when combined with food allergies that require additional exclusionary measures. Given the persisting call for more 'plant-based' eating, disproportionate reliance on 'protein alternatives' may result in higher consumption of processing contaminants and anti-nutritional compounds, as well as a higher proportion of ultra-processed foods. In excess, some improperly prepared or treated plant-based foods could lead to higher intakes of harmful substances like cariogenic sugars, fructose, mycotoxins, heavy metals, pesticide residues, plant-derived toxins, phytoestrogens, allergens, oxidation products, and acrylamide. Additionally, diets that are very low in fat and high in fibre may cause increased flatulence and bowel discomfort. The health impact of plant-based diets largely depends on the specific food items chosen, and individual health status should also be considered.

Nutritionism as an alibi for ultra-processing

Nutrient profiling systems designed to assess the healthiness of foods, and used for Front-of-Pack labelling and nutritional advice, may not only exaggerate the risks of animal source foods but also underestimate the risks of ultra-processed foods (UPFs). Food corporations exploit such models to reformulate products superficially without addressing the true health impacts of UPFs. UPFs have become prevalent, with negative impacts on health and the environment. UPFs are typically made from cheap, extracted, and refined ingredients, lacking in whole and fresh components. They often contain additives and are designed to be hyper-palatable, leading to quasi-addictive behaviours and mindless eating. UPFs are aggressively marketed, and corporations use greenwashing and nutri-washing tactics to create demand within global supply chains. As such, they replace traditional meals and contribute to the atomization of society. UPFs disproportionately affect lower socioeconomic groups, exacerbating nutritional imbalances.

Further reading (summary of the literature):

The above-mentioned reductionist view on what constitutes a healthy diet leads to nutritionism and the setting of agendas [Scrinis 2013; Leroy et al. 2022]. This is being promoted and amplified by food corporations that consistently benefit from a methodology that favours the fragmented analysis of single nutrients and foods. As such, it has 'diverted attention from the study of the ingredients, additives, and processing techniques used in the manufacture of ultra-processed foods', while it 'has also obscured the broader social, commercial, and ecological determinants of dietary health' [Scrinis 2020]. The impact of ultra-processed foods on various environmental dimensions is indeed very substantial [Scott 2018; Fardet & Rock 2020; Seferidi et al. 2020; Anastasiou et al. 2022].

There have been deliberate attempts by multinational corporations [e.g., WBCSD 2021] and their associated researchers to create confusion about the food category of ultra-processed foods, for instance by conflating it with 'processed foods' in general or by claiming that the category is too vague to be workable [Lawrence 2022]. The problem, however, should not be restricted to the simple degree of processing (in many cases, processing may be beneficial), so that a more comprehensive description is needed. The inferior quality of their ingredients is at least as important, if not more so, as ultra-processed foods are 'mostly constructed from a narrow range of cheap, extracted, refined and fractionated ingredients (for example, sugars, starches, vegetable oils, protein isolates, milk powders and mechanically separated meat), while lacking in whole, intact and fresh, ingredients' [Scrinis & Monteiro 2022]. As such, they are typified by a high degree of 'artificialization at the food level', based on the use of additives (e.g., colourants, flavours, artificial sweeteners, and emulsifiers). In addition to those technological criteria, ultra-processed foods are typically generated by transnational corporations 'to create branded, convenient (durable, ready-to-consume), attractive (hyper-palatable) and highly profitable (low-cost ingredients) food products often designed to displace all other food groups' [Monteiro et al. 2018, 2019]. They 'bypass the body's satiety signals and elicit quasi-addictive behaviours' [Scrinis & Monteiro 2022]. As the social level, they tend to replace the rich experiences of shared traditional meals with a plethora of often individualized ready-made products, leading to both mindless eating and further atomization of society [Anastasiou et al. 2022]. Aggressive marketing, greenwashing, and nutri-washing, are used to 'drive up demand and create new food cultures, construct global supply chains to obtain cheap ingredients, and use extensive packaging that encourages mass production, long-distance transportation, and waste related to their consumption' [Seferidi et al. 2020]. As such, they reinforce the position of large corporations, to the detriment of smallholder production [Baker et al. 2020]. Within the food and drink portfolio of the world's largest food corporation, 70-90% of the items could be considered as unhealthy [Evans 2021; Nestle 2021; Bandy et al 2023].

Nutrient Profiling Systems (NPS) only seem to aggravate the situation, exaggerating the risks associated with ASFs and underestimating the risks associated with ultra-processed foods [Ortenzi et al. 2022]. It comes as no surprise that such nutrient-centric dietary models and Front-of-Pack labels (e.g., NutriScore or Health Stars) are usually embraced by food corporations [e.g., Nestlé 2020]. On the Spanish market, for instance, 1/4 and 1/2 products within the favourable NutriScore categories A and B, respectively, are ultra-processed foods [Romero Ferreiro et al. 2021]. Such models require small sacrifices but meanwhile associate the harms of the foods they produce with high energy density and elevated concentrations of specific nutrients (sodium, sugar, saturated fat, etc.), which can be conveniently addressed through what is the core expertise of such corporations: ultra-processing. Products are then reformulated to somewhat reduce the levels of some of these nutrients (e.g., with synthetic sweeteners, salt replacers, texturizers, flavouring agents), or by adding ingredients with a healthy aureole (e.g., fibre or vitamins). This says little about true improvement of the healthiness of a food. The adverse consequences of ultra-processed foods are generally independent of dietary quality or patterns, which undermines the idea that reformulation would mitigate against negative health outcomes [Dicken & Batterham 2022]. In some cases, such interventions may even be potentially harmful, for instance when adding artificial sweeteners, when using emulsifiers in fat-lowering formulations, or when generally restructuring the food matrix through ultra-processing [for a detailed discussion, see elsewhere on this website].

In France, not only 2/3 of conventional industrial foods are to be categorized as ultra-processed, but also half of the products that are labelled as organic [Davidou et al. 2021]. Typically, they are based on refined oils, extracts, starches, and/or sugars. Similarly, the market for 'plant-based' mock ASFs [see elsewhere] has been embraced by large food multinationals, given that such foods are usually highly processed concoctions [Bohrer 2019], yet can be greenwashed based on narratives relating to 'planetary health' [see elsewhere]. In a French cohort study, vegetarians and vegans (especially those who started such diets more recently) had a higher intake of ultra-processed products than meat eaters, driven by a higher consumption of mock foods [Gehring et al. 2021].

Ways forward?

Future health policies should move beyond a narrow focus on nutrients or even foods, and consider dietary patterns as well as the broader social, commercial, and ecological determinants of health. Instead of monolithic top-down approaches, a reappraisal of culinary legacies could offer more constructive options that accommodate personal and cultural preferences. Foods associated with the recent 'Western diet,' particularly ultra-processed foods (UPFs), should be approached with caution. UPFs may serve as a primary target for preventing non-communicable diseases, including colorectal cancer. Their harmful effects may be attributed more to the act of ultra-processing itself rather than the nutritional content. Adequate essential nutrition, including sufficient protein and micronutrients, should also be a focal point of public health policies to address deficiencies that persist globally.

Further reading (summary of the literature):

Future health policies should not only limit themselves to understanding 'the role of the various dietary dimensions that mediate health (i.e, nutrients, foods, and dietary patterns)' but also 'account for the role of social, commercial, and ecological determinants of health' [Scrinis 2020]. As an alternative to monolithic top-down approaches, proposing a narrow view on what may constitute a healthy diet [see elsewhere], a reappraisal of our various ancestral diets and culinary legacies may be considered as a more constructive way forward. This has the potential to provide a myriad of fallback options that allow for personal and cultural needs and preferences [Best & Ward 2020]. In contrast, foods that are typically associated with the historically recent 'Western diet' (dating back a mere 4-5 generations), warrant suspicion. This is the case for high intake of sugar [Avena et al. 2008; Yang et al. 2014], refined grains [Swaminathan et al. 2021], often as high-carb/high-fat concoctions with seed oils.

Efforts to correct public health will need to deal with those dietary factors that trigger a metabolic state of hyperinsulinemia, chronic inflammation, and abnormalities of the vascular endothelium. Based on strength of association and mechanistic insights, the latter responses may not only have to be considered as the most important markers for diseases of modernity, but also as potential causes of metabolic dysfunction [Kohrt et al. 1993; Bao et al. 1996; Wang et al. 2007; Rajendran et al. 2013; Chen et al. 2015; Tsoupras et al. 2018; Adeva-Andany et al. 2019; Noakes 2021; Global Cardiovascular Risk Consortium 2023] and alteration of the homeostatic body weight 'set point', for instance via changes in brain dopamine [Darcey et al. 2023].

In that respect, it is not fully understood to which degree specific foods negatively affect metabolic health in a clear and causal manner. However, it is known that the consumption of ultra-processed foods generally leads to higher energy intake levels and weight gain compared to an unprocessed diet [Hall et al. 2019]. Also, decreasing the dietary share of UPFs reduces the symptoms of depression [Lane et al. 2023]. Such results from intervention trials are to be combined with increasing concerns about the constituents and biochemical make-up of UPFs [e.g., Fardet 2016].

Taken together, UPFs may have to be considered as a primary modifiable target for early prevention of non-communicable diseases [Touvier et al. 2023], including colorectal cancer [Hang et al. 2022], as well as mental health problems [Lane et al. 2023]. In fact, the harmful effects of Western foods may be less a matter of poor nutritional value than of the impact of ultra-processing as such [Bonaccio et al. 2022; Touvier et al. 2023], largely through food matrix degradation [Fardet & Rock 2022], effects on the gut microbiome [Zinöcker & Lindseth 2018; Smith et al. 2022], and addictive eating [Schulte et al. 2015; Gearhardt & Difeliceantonio 2022]. Consumption of ultra-processed foods can result in inflammatory responses ("fast food fever") [Myles, 2014; Hoffman 2022], reduced water intake [Galastri Baraldi et al. 2021], overeating due to soft textures [Forde et al. 2020] and altered glycemic responses [Fardet 2016], and harmful effects due to a higher intake of additives (colourants, artificial sweeteners, flavours, emulsifiers, ...), fillers, products from chemical hydrogenation, and various neo-formed substances [Dalenberg et al. 2020; Sandall et al. 2020; Viennois et al. 2020; Debras et al. 2022; Neumann & Fasshauer 2022; Scrinis & Monteiro 2022; Suez et al. 2022; Vissers et al. 2022; Zangara et al. 2022; Martínez Steele et al. 2023; WHO 2023a, 2023b]. Harmful contaminants, e.g. endocrine-disrupting chemicals in the abundant packaging materials, could also play a role [cf. Diamanti-Kandarakis et al. 2009; Buckley et al. 2019]. For plant-based 'meat', for instance, a weakened gastrointestinal digestive function and lower digestibility has been found in mice, when compared to real meat [Xie et al. 2022].

In parallel to the avoidance of nutrient-poor and hyperpalatable foods, the concept of adequate essential nutrition serves as a meaningful foundation of public health, as protein and micronutrient deficiencies are still of major concern globally, including both the West and low- and middle-income countries [Bailey et al. 2015; Keats et al., 2019]. Adequate protein, vitamins, and mineral intake levels represent the true nutritional challenges for mid-century [Medek et al. 2017; Nelson et al., 2018]. Public health policies should take this unambiguous data as their main mission, rather than overemphasizing findings derived from nutritional epidemiology of chronic disease, and all of the problems that come with that [see elsewhere].

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