There has been a growing focus on the degree of processing of foods as a way of looking at the nutrition and health relationship. A classification system has been developed however it is worth looking at the evidence surrounding the concept of ‘ultra-processed foods’.
What are ultra-processed foods?
According to a 2014 Systematic Literature Review, there are five systems used globally to assess the level of food processing of foods and diets. They are typically used to describe population eating patterns and describe a nation’s food supply. The NOVA system (a name, not an acronym) is the most common and promulgated by a group of public health academics (Monteiro et al) from the University of Sao Paulo in Brazil. NOVA categorises foods into four groups according to the extent and purpose of food processing: unprocessed or minimally processed foods (group 1), processed culinary ingredients (group 2), processed foods (group 3) and ultra-processed foods (UPF) (group 4).
The NOVA system of classifying the level of processing of food
Group 1. Unprocessed or minimally processed foods.
Unprocessed foods are edible parts of plants, animals, fungi, algae and water after separation from nature.
Minimally processed foods are altered by processes such as removal of inedible or unwanted parts, drying, crushing, grinding, fractioning, filtering, roasting, boiling, pasteurising, refrigerating, freezing, packaging or non-alcoholic fermentation. This processing makes the food palatable and may extend the life of the food but does not involve adding salt, sugar or fats, although sometimes additives may be used to preserve the food or nutrients added to replace nutrients lost during processing. This group also includes combinations of natural or minimally processed foods.
Examples: apples, frozen raspberries, carrots, baby spinach leaves, frozen mixed vegetables, rice, rolled oats, eggs, salmon steaks, dried mushroom, nuts, ground coffee, pasteurised milk, natural yogurt, unsweetened juice, muesli.
Group 2. Processed culinary ingredients
These are ingredients used with group 1 foods to prepare enjoyable dishes and meals and are rarely consumed on their own. They may be pressed, refined, milled or spray dried. They may also be a combination of group 2 foods and may contain additives to preserve their original properties, such as antioxidants added to oils.
Examples: salt, sugar from sugar cane or beet, honey, maple syrup, vegetable oils, vinegar, butter, lard and cornflour.
Group 3. Processed foods
Processed foods are relatively simple products with two or three ingredients made by adding group 2 ingredients to group 1 foods and may involve preservation or cooking methods including non-alcoholic fermentation. The processing is done to increase durability or improve their sensory appeal. They may contain additives for preservation. Fermented alcoholic drinks such as beer, wine and cider are included in this group.
Examples: canned or bottled vegetables and legumes, canned fruit, canned fish, cured meats, roasted and salted nuts, cheese, bread, wine and beer.
Group 4. Ultra-processed food and drink products.
Food in this group are formulations with five or more (usually many) ingredients, including group 2 ingredients and additives not commonly used in culinary preparations. Group 1 foods are a small proportion or even absent. Ingredients in these foods can include substances extracted from foods such as casein, lactose or gluten, or derived from further processing of food constituents such as soy protein isolate, maltodextrin or hydrogenated oils. They are produced using processes with no domestic equivalents. The purpose of this level of processing is to produce foods ready to consume, or easy to reheat, and to replace unprocessed and minimally processed foods and freshly prepared foods. Distilled alcoholic beverages such as spirits are included in this group.
Examples: carbonated drinks, packaged snacks, ice cream, chocolate, confectionery, mass produced packaged breads, margarines, biscuits, cakes, breakfast cereals, energy bars, instant sources, infant formula, meal replacements, pies, pizza, fish fingers, chicken nuggets, sausages, burgers, hot dogs, instant soups and noodles and desserts, whisky, gin, vodka. Natural yoghurt with artificial sweetener is included because it has cosmetic or sensory intensifying additives.
How much are we eating?
The NOVA system has been applied to food intake and food composition data in several descriptive studies. A US study estimates UPFs make up 58% of the American diet and contribute 89% of added sugar consumption. The latter finding is not surprising as “added sugars” are a major defining element in the UPF category. In Canada, 61.7% of dietary energy has been described as coming from UPF. In Australia, 36% foods in the AUSNUT (2011-13) food composition database were classified as UPF using the NOVA system - 38% were Minimally Processed (MP) and 24% Processed (P). In New Zealand, 84% of packagedfood products were classified as UPF. Interestingly, there was little price difference between levels of processing, underlining the value offered by convenience foods for time-poor consumers. The New Zealand study found a positive association between level of industrial processing and lower nutrient profile as determined by the FSANZ Nutrient Profiling Scoring Calculator (NPSC), however this is not always the case in other studies; energy from UPFs does not always correlate with nutrient intake.
Controversies around NOVA
Monteiro and colleagues claim UPF are typically hyper-palatable, highly marketed, use health claims, highly profitable and sold under brands owned by transnational corporations. They say UPFs are associated with a variety of adverse health outcomes including obesity, metabolic syndrome and dyslipidemia, as well as reductions in dietary nutrient content. They describe UPFs generally as energy-dense, high in unhealthy types of fat, refined starches, free sugars and salt, and poor sources of protein, dietary fibre and micronutrients. They are critical of UPFs, not only for their unhealthy nutrient profiles, but from a social, cultural, economic, political and environmental point of view. They claim UPFs displace minimally processed and freshly prepared local and cultural foods.
However, their views have been challenged. A critical appraisal by Gibney et al challenges the basic assumptions of using NOVA to examine links between food and health, and describe the NOVA system is simplistic, crude and starkly different to many existing food classification systems. A key criticism is that the UPF category is so broad. How can food-based dietary guidelines be developed based on such a variety of different foods – from bread to soft drinks - with such varying nutrient profiles? They believe there is no evidence supporting the idea that UPFs give rise to hyperpalatable foods that are “addictive” or give rise to diets low in micronutrients. They also find the evidence does not support UPFs are driven by globalisation because in low- to middle-income countries production is driven by small local companies.
In another critical review of the evidence linking UPF with obesity, the authors ask, is it the level of processing of UPF or the nutrient content influencing obesity? The conclude more longitudinal research is needed to help answer the question.
Are all UPFs unhealthy?
Because UPFs cover such a broad group of foods, they are not all unhealthy using more conventional epidemiological definitions. Some of our nutrient-rich core foods such as bread and breakfast cereals are classified as UPF, as well as many healthy frozen and pre-prepared meals. There is an apparent bias toward home-prepared foods and against manufactured food in NOVA, irrespective of nutrient (or food) content. For example, products with more than 5 ingredients are considered ultra-processed when produced in a factory, whereas many recipes made at home have long lists of ingredients. This anti-manufactured food element places it uncomfortably against the modern food supply of increased convenience foods and the social changes that demanded them.
Do UPFs fit within current Dietary Guidelines?
The idea of reducing UPF intakes for better health is mostly consistent with Dietary Guidelines. Discretionary foods such as sugar sweetened beverages, cakes, biscuits, savoury packaged snacks are classified as UPF and there is little argument we need to be eating less of these. Sugar is classified as a group 2 processed culinary ingredient used to produce enjoyable (and nutritious) dishes but can also be an ingredient in UPFs of low nutritional value and contribute to excess added sugars consumption. This reflects the place of sugar in the Dietary Guidelines. The misalignment is with nutrient-rich core foods such as breads, breakfast cereals and healthy ready meals classified as UPF because they are manufactured rather than prepared at home. In the Australian and New Zealand contexts these offer nutritious and convenient core food options that enhance nutrient intake. Current systems of defining foods as core or discretionary appear to serve us better.
The bottom line
The NOVA system is one way of grouping foods, however it has attracted criticism for its lack of evidence base. The NOVA system has produced a new term: Ultra-Processed Foods (UPF). The category of UPFs is broad and includes some nutritious core foods as well as nutrient-poor discretionary foods which limits its application within nutritional epidemiology and public health nutrition advice.