Ultra-processed food and health

In order to identify food groups with a potentially detrimental effect on health and thus be able to guide public health policies on food, different food classification systems have appeared according to their degree of processing, such as the NOVA system.

The NOVA (a name, not an acronym) food classification system has been the most applied in the scientific literature and it is accepted today by international organizations such as FAO or WHO. This system classifies all foods into four groups (Figure 1) according to the extent and purpose of the industrial processing they undergo considering physical, biological and chemical methods used during the food manufacturing process, and the use of additives.

Figure 1. The NOVA food classification system according to Monteiro et al., (2010).(Click to expand)

Group 1 consists of fresh (or natural) foods, which include the edible parts of plants (such as seeds, legumes, fruits, leaves, stems, roots) or of land and marine animals, and also eggs, milk, mushrooms, algae and water. In this group minimally processed foods, which are natural foods that undergo processes that include removal of inedible parts, grinding, cutting, non-alcoholic fermentation (as for natural yogurt), pasteurization, sterilization, refrigeration, freezing, packaging and vacuum packaging, are also included.

Group 2 includes processed culinary ingredients, which are products obtained directly from nature or from Group 1 foods by pressing, refining, crushing, pulverizing, etc. Oil, salt, sugar, spices, butter, cream and honey are included in this group. These products are obtained and processed to be used to help prepare, season and cook group 1 foods and obtain, as a whole, a “homemade” recipe.

In Group 3, processed foods that are prepared by adding salt, oil, sugar, or other Group 2 substances to Group 1 foods are included. These foods normally have 2 – 3 ingredients. The type of processing of this group of foods can include various preservation methods, such as salting (cured ham, salted cod or salted nuts), smoked (salmon), or canned vegetables and legumes.

Group 4 is constituted by ultra-processed foods, which are formulations of ingredients generally produced through a succession of industrial techniques, processes and additives. They include sugars, salt, fats, in addition to other caloric sources and nutrients that are extracted directly from food (casein, lactose, whey, gluten, starches, etc.) or that are obtained through more complex processes (hydrogenated oils, hydrolyzed proteins, purified soy protein, high fructose corn syrup, etc.) and/or additives (antioxidants, stabilizers, colorants, flavor enhancers, sweeteners, emulsifiers, etc.). In this group we can find sweets and pastries, industrial pizzas, industrial breads, ice creams, sugary drinks, energy drinks, dairy desserts, sauces, salty snacks, breakfast cereals, margarine, etc.

Nowadays, ultra-processed foods are really convenient (ready-to-consume and long shelf-life) and very attractive (hyper-palatable) for consumers, and highly profitable (low cost of ingredients) for their manufacturers. However, these foods are typically nutritionally unbalanced and tend to be over-consumed and replace all other NOVA food groups.

Consequently, people most likely to go hungry have more access to ultra-processed foods and are at highest risk of diet-related diseases, showing that food insecurity and poor nutrition are closely related. In fact, food insecurity has been defined as the state of being without reliable access to a sufficient quantity of affordable and nutritious food.

In 2020, more than 820 million people were undernourished and at least 2 billion more lacked sufficient nutrients; and paradoxically, there were more than 2 billion people who were overweight or obese. In order to make fresh foods and minimally processed foods, which have better nutritional quality, more valued, available and affordable for all, public health policies and market incentives are needed.

In addition, the occurrence of the Maillard reaction is favoured in ultra-processed foods. The optimal conditions needed for this reaction to take place (high pH and temperature, water activity (0.5 – 0.8) and chemical composition) are present during the production of ultra-processed food.

Consequently, harmful Maillard reaction products, such as acrylamide and advanced glycation end-products (AGEs), are formed and their intake has been associated with a greater risk of developing non-communicable chronic diseases.

In summary, there is consistent evidence accumulated by different studies carried out in a great number of countries, that shows that the replacement of non-ultra-processed foods by ultra-processed foods increases the risk of obesity and other diet-related non-communicable chronic diseases, and also premature mortality.

Therefore, the consumption of ultra-processed foods should be avoided for the healthy ageing of the global population.

Authors: Dr Dolores del Castillo and Dr. Amaia Iriondo-DeHond