Proper, balanced, moderate, and diverse. These are the characteristics that a healthy diet must have, as stated by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) in a recent public declaration.
With these recommendations, the WHO aims to bring order to the complex landscape of nutrition, starting from an argument that we should all be clear about before experimenting with food. "A healthy diet promotes health, growth, and development. It is the foundation of an active lifestyle, prevents deficiencies and nutrient excesses, communicable and non-communicable diseases, food-related pathologies, and ultimately promotes well-being."
According to the FAO and WHO, "the role of diets in health promotion and the need to deepen their interconnection with environmental protection are more evident than ever."
Meat, yes or no? Are carbohydrates as 'bad' as they are portrayed? Should we stop drinking cow's milk? In a scenario full of unresolved doubts, contradictory information, myths, and 'miraculous' options that are actually the opposite, the international organization overseeing our health is serious and warns us that, besides harming us internally, "the lack of consensus on what constitutes a healthy diet can undermine progress and the continuity of efforts to achieve it."
To advance towards the interconnection between health protection and environmental care, the WHO and FAO have formulated the principles on which a healthy diet should be based, according to scientific literature and the regulatory framework established by both institutions.
So, based on the fact that there are multiple alternatives that meet the necessary requirements to be considered as viable options, they detail how a healthy diet should be.
Firstly, it must be adequate. What does the WHO understand as an adequate diet? An adequate diet is one that covers, without exceeding, the specific nutrient requirements for age, gender, size, body composition, levels of physical activity, physiological states (e.g., pregnancy), and health conditions of each individual.
This document explains that the body is unable to synthesize most essential nutrients and must therefore obtain them from the diet. What are the essential nutrients? Essential amino acids, essential fatty acids, and most vitamins and minerals.
Essential nutrients are involved in all functions of our body: fetal and infant development, growth, and the functioning of all our organs and muscles throughout life.
Inadequate intake of essential nutrients can lead to specific deficiency syndromes (such as scurvy due to vitamin C deficiency, rickets due to vitamin D deficiency, or goiter due to iodine deficiency), many of which are uncommon today.
However, many others still affect a large part of the population today, causing growth problems or brain development issues and failures in the immune system. The WHO and FAO focus on the importance of meeting the nutrient needs of children aged zero to 23 months, due to the growth and development phase they are in.
The second requirement of a healthy diet is that it is balanced in energy intake and in the sources from which it obtains that energy (fats, carbohydrates, and proteins) to promote a healthy weight, adequate growth, and disease prevention.
The energy doses that we must ingest in the form of food vary according to age, sex, and levels of physical activity, and obviously during pregnancy and lactation.
Healthy diets require an appropriate balance of the three main sources of energy: proteins, fats, and carbohydrates, depending on the individual needs of each person.
Proteins, they remind us, are the basic components of many structural elements of the body, such as muscles, and functional molecules, such as hormones and enzymes.
To meet the body's needs, between 10 and 15% of the calories consumed per day should come from proteins. This percentage may be slightly higher during adolescence and in the case of athletes, bodybuilders, and other individuals actively working to increase or maintain a significant amount of muscle mass.
Proteins can come from a mix of animal and plant sources, and in their choice, digestibility and quality should be considered, especially in childhood and adolescence.
In some contexts, it may be preferable for adults to switch to plant protein sources to reduce the risk of cardiometabolic diseases.
In this chapter, the WHO and FAO issue a warning about a 'trend' that can be harmful to our health: consuming excessive amounts of proteins can be a metabolic burden on the body, especially on the kidneys.
Fat is also an essential nutrient for the proper functioning of the body's cells, and two fatty acids - linoleic acid and linolenic acid - can only be obtained from the diet. Therefore, in adults, a minimum of 15-30% of the calories consumed per day should come from fats.
But not all fats are equal. Their source should mainly be unsaturated fatty acids (olive oil, avocado, nuts, fatty fish...).
An elevated fat intake can lead to excessive energy intake, so limiting consumption to 30% or less can help reduce the risk of unhealthy weight gain. However, this percentage can be exceeded as long as energy balance is maintained and recommendations on fat quality are also met.
No eliminating carbohydrates! The WHO and FAO make it clear: carbohydrates are the main source of energy for the body.
The amount of carbohydrates in the diet can vary, and daily intake should cover the remaining percentage after considering proteins and fats. Therefore, the amount should be equal to or less than 75% of total daily calories, but generally at least 45%.
No white pasta, pizzas, or sweets. Carbohydrates should mainly come from whole grains, vegetables, fruits, and legumes.
Adults should aim to consume at least 400 grams of fruits and vegetables and 25 grams or more of natural dietary fiber each day.
Moderate. That would be the third key characteristic of a healthy diet. In this regard, the WHO and FAO emphasize that although some nutrients are essential, in higher amounts than recommended, they can have negative health effects.
For example, sodium, which is an essential mineral, but in high intakes, is associated with increased blood pressure that can lead to cardiovascular diseases. Therefore, sodium intake should be limited to 2 grams per day (equivalent to 5 grams of table salt, i.e., sodium chloride) in adults and proportionally lower in children and adolescents.
Keeping sodium consumption within this limit would help maintain the systolic and diastolic blood pressure of adults and children within healthy ranges, with a consequent decrease in the risk of stroke, cardiovascular events, and related mortality.
The WHO and FAO are firm about those non-essential nutrients associated with negative health effects: they should be consumed in moderation or excluded from the diet.
What are those non-essential nutrients that should be limited or eliminated? Free sugars are not essential nutrients, and their intake should be limited to less than 10% (only less than 5% is associated with additional health benefits).
Reducing the consumption of free sugars should be achieved by also avoiding the use of non-sugar sweeteners, as evidence suggests that they do not help control weight in the long term or reduce diet-related NCD risk.
No more than 10% of daily energy should come from saturated fats and no more than 1% from trans fats. Industrially produced trans fats (e.g., partially hydrogenated oils) should not be used, so they should come exclusively from ruminant meat and dairy.
This document emphasizes the importance of avoiding or moderating the consumption of foods that can have negative health effects, especially when consumed in high amounts.
What are those foods harmful to health? Saturated fats, free sugars, or those containing other compounds that can be harmful to health.
This section emphasizes the issue of red and processed meats and highly processed or ultra-processed foods. The WHO and FAO underline that in adults, a high intake of red meat is associated with a greater risk of several diseases, and recent research suggests that even low levels of processed red meat consumption can have negative health consequences.
Both organizations emphasize that there is increasing evidence that the consumption of highly processed foods (both foods and beverages), labeled as ultra-processed (UPF) by the NOVA classification system, is associated with negative health effects such as the risk of premature mortality, cancer, cardiovascular diseases, overweight, obesity, type 2 diabetes, as well as the deterioration of mental, respiratory, and gastrointestinal health.
Ultra-processed foods have a high content of fats, sugar or artificial sweeteners, sodium, or food additives, but their negative health effects go beyond this as they undergo processing processes that alter the structure of the original food ingredients.
The WHO warns us about a very concerning fact: an acceptable level of ultra-processed food consumption has not yet been defined, and further research is needed to understand the relationships between their intake and the development of diseases.
Finally, in fourth place, WHO and FAO point out the convenience of having a varied diet, which, according to scientific literature, is associated with a higher probability of meeting the vitamin and mineral needs of our body (with the only exception of infants who, during the first six months of life, should be exclusively breastfed, if possible).
As stated in this report, several studies have found lower rates of mortality and diet-related NCDs among participants with a greater diversity of food groups, greater diversity within specific food groups (for example, fruits and vegetables), and greater diversity of species in complete dietary patterns.