Balancing Adequate Nourishment with Cultural and Individual Preferences
A recent study published within the framework of the Denver Call for Action highlights the importance of culturally appropriate diets, which enable individuals to select nutrient-dense, minimally processed foods tailored to their personal and cultural preferences. The research is interdisciplinary, combining expertise from nutrition, food history, technology, and cultural studies, and aims to align nutritional status with individual values, sustainability, and practical constraints. It highlights the need for adequate nourishment, particularly for groups with unique nutritional needs, such as children, pregnant and lactating women, and older adults.
Diets dominated by ultra-processed foods can be harmful
Incorporating animal-source foods at a level of one-fourth to one-third of total caloric intake can improve nutrient density, whereas consuming below this threshold increases the risk of nutrient deficiencies. Additionally, minimally processed foods are recommended; however, processing is necessary for plant-based diets to remove phytotoxins and enhance the bioavailability of nutrients. However, excessive processing can compromise food quality, and diets dominated by ultra-processed foods are likely to be harmful.
In wealthy countries, the debate over ultra-processed foods and animal-based products, particularly red meat and animal fats, dates back to the Progressive Era in the United States (1890s–1920s), when diet reformers promoted bland, “rational” foods over traditional ones, believing that people couldn’t manage their diets. Red meat, sugar, and white bread were seen as harmful, while whole grains, nuts, and fruits were encouraged. These ideas influenced social values and shaped modern perceptions of healthy eating. Over time, this has contributed to the belief that certain diets, such as those excluding red meat, are healthier, particularly in North American studies. The term “healthy diet” has become unclear, leading to a focus on “adequate nourishment” to address personal, cultural, and biological needs, not just disease prevention.
The idea of a “perfect” universal diet is flawed
Despite efforts to create healthy dietary guidelines, diet-related diseases continue to rise, with only 7% of U.S. adults having good heart and metabolic health. Current guidelines face three main issues: they can be too strict or culturally imposing, especially Western diets for all populations; they ignore that different diets (e.g., low-carb, Indigenous, traditional) can meet nutritional needs in various ways; and the idea of a “perfect” universal diet is flawed, as our bodies may naturally select the right foods unless influenced by ultra-processed foods.
Most dietary guidelines are based on observational studies, which can lead to overly strict advice, such as excessive fat avoidance, and expert consensus can be too strong without solid evidence. The article advocates for a flexible dietary framework that considers nutrient density, the balance of animal and plant foods, food processing levels, and the fulfilment of nutritional needs, thereby creating a “dietary space” for healthier, personalised, and culturally relevant eating habits.
Humans are highly adaptable omnivores
Humans are highly adaptable omnivores, capable of thriving in diverse environments ranging from tropical to Arctic regions. This adaptability is reflected in the diets of ancestral populations, where animal-source foods played a central role in many hunter-gatherer diets. Studies show that 50% of energy in modern forager groups came from animal sources, with similar trends observed in Palaeolithic foragers, where animal foods provided 30% to 70% of caloric intake. Environmental factors, such as climate, may have influenced the prevalence of more carnivorous diets.
Animal foods are often preferred due to their high energy density and easier acquisition, especially before the domestication of calorie-dense crops. Food processing has been key to human dietary adaptability. Early humans employed methods such as soaking, fermenting, and cooking to enhance the safety and digestibility of food, particularly for plant-based foods that contain toxins and antinutrients. Modern technologies, such as fortification and biofortification, now enhance the nutrient profile of plant foods, compensating for nutrients like iron, zinc, and vitamin B12, which are more readily available in animal foods.
Humans are biologically adaptable, but…
Humans are biologically adaptable, benefiting from advanced food processing, but there are limits to this flexibility. Diets based solely on fortified macronutrient blends lack true nourishment, as they often miss essential bioactive compounds. Over-restriction of animal-source foods can undermine culturally and nutritionally beneficial whole-food strategies. Plant-based diets may lack certain essential nutrients, while ultra-processed foods, which lose nutrients and may contain harmful compounds, pose further risks.
Animal-source foods such as red meat, fish, eggs, and milk provide key nutrients often lacking in diets. Historically, the animal-to-plant ratio in diets has shifted, leading to lower nutrient density in modern diets. Diets with at least 25% of calories from animal foods are more likely to meet micronutrient needs, while diets like the EAT-Lancet diet (14% animal food) lead to deficiencies without fortification. Moderate consumption of animal-source foods, as seen in Mediterranean diets, is associated with lower mortality and a reduced risk of cardiovascular disease. Evidence now suggests that the harmful effects of moderate animal food consumption, particularly eggs, poultry, and whole-fat dairy, are being questioned. Moderate red meat consumption, however, is not significantly harmful when part of a whole-food diet. However, more research is needed to assess the risks and benefits of high animal-source food intake.
Ultra-processed foods should be minimised
Processing can enhance the nutritional value of diets, but excessive industrial processing, particularly of ultra-processed foods, raises significant health concerns. The NOVA classification categorises foods into four groups: 1) unprocessed or minimally processed, 2) processed culinary ingredients, 3) traditionally processed, and 4) ultra-processed foods. While categories 2 and 3 are safe in moderation, ultra-processed foods (category 4) should be minimised due to their artificial additives, hyper palatability, and potential health risks.
These foods, made from cheap refined ingredients, can displace essential food groups. Minimally processed foods (Category 1) are recommended; however, their nutrient density varies, so nourishment depends on both the level of processing and the nutrient content. Food processing, such as cooking or fermentation, is beneficial, especially for animal-source foods and plants. Whole-food diets with some traditionally processed foods are generally healthy, but ultra-processed foods are linked to increased calorie intake and poor health outcomes. Despite uncertainty around the evidence, ultra-processed foods may disrupt physiological functions and harm health. While complete avoidance may be impractical, consumption of ultra-processed foods should be minimised.
Dietary needs vary by life stage
Dietary needs vary by life stage, with special considerations for infants, children, pregnant women, and older adults. Failure to meet nutritional needs during critical periods, like the first 1,000 days of life, can lead to long-term consequences. The WHO recommends that children aged 6 to 23 months consume animal-source foods to address nutritional gaps. For low-income countries, dietary frameworks should emphasise affordability and incorporate food processing interventions, like fortification, to improve food security. Dietary guidelines often prioritise disease prevention but may overlook adequate nourishment and population preferences. Future guidelines should allow for more flexibility, incorporating diverse eating habits while ensuring nutritional adequacy, with an emphasis on nutrient density, processing levels, and the balance between animal and plant sources. Self-selection of nutrient-dense, minimally processed foods can enhance dietary flexibility while ensuring nutritional adequacy.