The Nourishment Table: balancing nutrient density and food processing

Nutritional debates often focus on two categories: processed foods, especially ultra-processed variants, and animal source foods like red and processed meats and animal fats. These debates have historical roots in early 20th-century diet reform movements during the Progressive Era in the USA, which aimed to improve public health through the scientific management of diets. Reformists advocated for government intervention to promote ‘rational’ diets over those based on tradition, targeting red meat and processed foods as harmful while promoting whole grains, nuts, and fruits. This movement laid the foundation for today's dietary guidelines, which continue to influence notions of ‘eating healthy’ and ‘eating right'. Despite these guidelines, nutrient deficiencies still constitute a public health problem, also in high-income countries, whereas diet-related non-communicable diseases have increased to epidemic proportions, with only a minority of adults currently in optimal cardiometabolic health. Given that existing dietary recommendations need to be considered as failed policy, novel dietary frameworks are needed that are rigorously evidence-based, regionally and culturally sensitive, and more recognisant of individual variations in both nutrient requirements and preferences.

Humans are remarkably adaptable omnivores. Food processing has been crucial in expanding dietary options by making otherwise inedible or toxic foods safe and nutritious. Plant processing, in particular, was essential for detoxification and enhancing nutrient availability long before the advent of agriculture. Early techniques included chopping, soaking, fermenting, and cooking, while modern advancements such as micronutrient fortification and supplementation have further enhanced the dietary potential of plants, reducing reliance on animal sources. However, simply fortifying foods cannot fully replicate the benefits of whole-food diets, which provide a diverse array of nutrients and bioactive compounds. Diets that are too low in animal source foods risk nutrient deficiencies, while excessive consumption of these foods has been linked to chronic disease risks, though these associations remain debated. Similarly, while food processing greatly broadens dietary options, excessive reliance on ultra-processed foods can lead to poor health outcomes. Balancing 1) nutrient density, usually correlating with the share of animal foods, and 2) appropriate levels of processing is essential for optimizing diets and ensuring adequate nourishment. In both cases, it is crucial to define what constitutes having ‘too little’ or ‘too much.’

Animal source foods are among the most nutrient-dense options available, providing essential nutrients that are often limited in global diets and less accessible from plant sources. While modern diets typically include fewer animal-derived nutrients compared to ancestral hunter-gatherer diets, human physiology is adapted to nutrient-rich diets that include substantial amounts of animal foods. Low intake of these foods, as seen in plant-heavy diets like the EAT-Lancet model, often leads to deficiencies in key micronutrients. To address this issue, it is recommended that 25-30% of total calories, or at least half of protein intake, come from animal sources; otherwise, careful supplementation and monitoring are necessary. Incorporating these levels of animal foods alongside nutrient-rich plants in traditional diets—generally minimally to moderately processed—has been linked to good health and a reduced risk of chronic diseases. Moreover, it is prudent to minimize the consumption of refined starches, sugars, and frying oils. While some ancestral diets may have achieved very high nutrient densities through elevated animal food consumption, recent research questions the health risks associated with such levels. Nonetheless, even if heavily animal-based diets may offer therapeutic potential in some cases, a balanced approach remains prudent.

Food processing is generally benign and enhances the nutritional value and flexibility of diets, though ultra-processing raises concerns for both animal and plant-based foods. Plant-heavy diets particularly benefit from traditional processing interventions; however, consumers who rely heavily on ‘plant-based’ mock foods risk consuming a high proportion of ultra-processed meals with unfavorable nutritional profiles. The distinction between processed and ultra-processed foods is not merely a matter of degree but a fundamental difference. The latter undergo extensive processing and consists of disrupted food matrices, primarily made from cheap, fractionated, and standardized ingredients. Such products exhibit a high degree of 'artificialization' and rely excessively on additives. They are often produced by transnational corporations aiming to create branded and profitable items that displace other food groups by being quasi-addictive and having low satiety value per calorie. Part of the reason for their success is that modern lifestyles have shifted away from traditional food preparation, resulting in increased demand for convenience foods and a loss of shared meal experiences. Unsurprisingly, diets dominated by ultra-processed foods are linked to poor health outcomes, including a higher risk of mortality. While much of the evidence remains of low certainty due to the observational nature of the studies, intervention trials indicate that these diets lead to overeating and increased caloric intake. While complete avoidance may not be feasible, nor required, minimizing ultra-processed food consumption is recommended.