ULTRA-PROCESSED FOODS – MUCH ADO ABOUT NOTHING?

These days, it seems like the dangers of ultra-processed foods are constantly lurking in the headlines, driven in part by an ever-increasing deluge of research linking their consumption to most diseases known to mankind. Should we all be concerned?

What are ultra-processed foods?

From a consumer’s perspective, it may be useful to think the phrase “ultra-processed foods” (UPFs) is a pseudo-scientific euphemism for what until recently has been colloquially called “junk food”. 

Most research on ultra-processed foods is based on the classifications used in the NOVA system. As mentioned in this month’s Food for Thought, the NOVA system currently has four main classifications:

1. Unprocessed or minimally processed foods.
2. Processed culinary ingredients.
3. Processed foods.
4. Ultra-processed foods

According to NOVA, ultra-processed foods are industrial formulations typically with 5 or more and usually many ingredients. Besides salt, sugar, oils, and fats, ingredients of ultra-processed foods include food substances not commonly used in culinary preparations, such as hydrolysed protein, modified starches, and hydrogenated or inter-esterified oils, and additives whose purpose is to imitate sensorial qualities of unprocessed or minimally processed foods and their culinary preparations or to disguise undesirable qualities of the final product, such as colorants, flavourings, non-sugar sweeteners, emulsifiers, humectants, sequestrants, and firming, bulking, de-foaming, anticaking, and glazing agents.

Not surprisingly, they encompass a wide range of foods and beverages, including (but not limited to): carbonated soft drinks (soda’s); sweet or savoury packaged snacks (e.g., corn chips, potato crisps/chips, etc…); ice cream, chocolate, candies (confectionery); mass-produced packaged breads, buns, cookies (biscuits), pastries, cakes and cake mixes; breakfast ‘cereals’, ‘cereal’ and ‘energy’ bars; margarines and spreads; processed cheese; ‘energy’ drinks; sugared milk drinks, sugared ‘fruit’ yoghurts and ‘fruit’ drinks; sugared cocoa drinks; meat and chicken extracts and ‘instant’ sauces; and many ready-to-heat products including pre-prepared pies and pasta and pizza dishes; poultry and fish ‘nuggets’ and ‘sticks’; sausages, burgers, hot dogs and other reconstituted meat products; and powdered and packaged ‘instant’ soups, noodles and desserts.

Is NOVA a valid system for classifying foods?

It is widely considered that the NOVA classification of UPFs lacks sufficient precision to be suitable for the characterisation or regulation of individual foods.

Indeed, many food and nutrition scientists question whether the NOVA system is classifying foods based on formulation or processing, which is compounded by defining ultra-processed foods as products that contain “…5 or more and usually many ingredients” as noted above. Scientifically, formulation is defined as the combination of ingredients and food additives added and prepared according to prescribed methods, to produce a product intended for further processing or ready for consumption. On the other hand, food processing is defined as the use of methods and techniques involving equipment, energy and tools to transform agricultural products such as grains, meats, vegetables, fruits and milk into food ingredients or finished food products. As such, formulation and processing are two different aspects of food production. Therefore, it is likely that application of NOVA to dietary data is classifying foods based more on formulation than processing.

Furthermore, in most research published to-date, the NOVA system has been applied to dietary intake data retrospectively. That is, the tools used to measure dietary intake were not specifically designed to measure a foods NOVA classification and have not been validated for that purpose. This is important because it is generally not possible with food frequency questionnaires (one of the most common tools used in observational studies), to determine whether a self-reported food was prepared/prepackaged or whether it was hand-made/home-made. As noted in this month’s Food for Thought, this results in classifications that can be described as a little ‘woolly’.

Finally, the definition does not take the amount or dose of an ingredient or additive into account – the simple presence of certain ingredients and additives make a food ultra-processed according to NOVA. In science, however, it is well known and understood that “…the dose makes the poison”.

Is NOVA reproducible?

A recent study involving more than 150 French food and nutrition scientists evaluated and classified 120 marketed foods and 111 generic foods using the NOVA system. Even though the evaluators had high confidence in their assignments, only 3 marketed foods and 1 generic food were assigned to the same NOVA group by all the evaluators, and most of the foods in both lists were placed in 2, 3, or even 4 different NOVA groups by different evaluators.

Therefore, the level of misclassification, even among food and nutrition scientists, is unacceptably high, and the results of this study severely undermine the validity of all of the observational studies on ‘ultra-processed foods’ and associated health outcomes.

How much ultra-processed foods are we consuming?

A recent systematic review of 99 observational studies conducted around the world estimated that ultra-processed food consumption varied from a low of 10% of energy in Italy to a high of 67.8% of energy in the UK:

Data from Europe over the past 20 years indicate that there was a modest decrease (2–15%) in UPF consumption observed over time in most nations, except for Finland, Spain and the UK (3–9% increases). The top contributors to the dietary energy share of UPFs in these nations were:

• fine bakery wares
• sausages
• sauces
• margarines
• crackers
• additional bread products
• breakfast cereals, and
• chocolate

Perhaps unsurprisingly, younger people consumed more ultra-processed foods than older people, possibly due to that fact that they have less time, money (see below) and/or cooking skills.

Ultra-processed foods and obesity

The same systematic review of European ultra-processed food consumption found that a countries’ burden of high body mass index (BMI) did not increase across increasing percentages of energy from ultra-processed foods, and overall, no correlations between ultra-processed foods consumption and BMI were observed.

A different systematic review and meta-analysis of 3 prospective cohort (observational) studies conducted in Brazil, Spain and the United Kingdom found a small association with BMI and ultra-processed foods consumption in adults. On the other hand, systematic reviews of observational studies in children and adolescents do not find any consistent associations between ultra-processed foods consumption and measures of overweight or obesity.

Finally, a recent systematic review of randomised controlled trials concluded that “…reducing the consumption of UPFs showed benefits on some anthropometric and dietary intake outcomes, although significant effects were not observed for most of the evaluated outcomes. The limited number and significant methodological limitations of the studies prevent definitive conclusions. Further well-designed and conducted RCTs are needed to understand the effects of UPF consumption on health.”

Is a diet low in ultra-processed food affordable?

A 2019 study in the USA estimated that the weekly cost for ingredients to prepare 8,400kJ (2000 Calories) per day of ultra-processed meals was US$161 versus US$229 for unprocessed meals. In other words, the diet low in UPFs cost US$68 more per week, or >40% more.

Similarly, a 2024 study compared the cost, shelf life (time to expiration) and diet quality of less-processed to more-processed foods, again using the NOVA system. The “per person” cost reflecting the amount of food needed to provide 8,400kJ (2000 Calories) per day was $9.85/day for the more-processed foods and US$15.91/day for the less-processed, or >60% more. Median time to expiration of the less-processed foods was 35 days versus 120 days for the more-processed foods. Finally, the less-processed foods diet had similar nutrient density and diet quality scores to the more-processed foods diet.

In other words, a diet higher in ultra-processed foods is nutritionally equivalent to one lower in ultra-processed foods, but it is significantly cheaper, and the foods last a lot longer.

Much ado about nothing?

There is a large and seemingly ever-increasing volume of evidence associating ultra-processed foods consumption with adverse health effects. However, most of the evidence is poor quality. The definition of ultra-processed foods is not clear to many scientists and food regulators, and it is difficult to apply in the real world. More high-quality research is therefore desperately needed before recommendations to reduce ultra-processed food consumption are made to the general public by means of dietary guidelines.

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