Recent months have seen growing interest in a newly-popularised idea in health and nutrition: ‘ultra-processed foods’.
The term refers to foods which fall in Category 4 of the NOVA classification system, and the public appears to have become increasingly wary of such foods in terms of their healthiness. While it is true that higher consumption of ultra-processed foods has been linked to worse health outcomes on average in epidemiological studies, this categorisation poses at least three problems.
First, the definition of the ‘ultra-processed’ category is not clear to consumers. Only 40% of consumers understand what ultra-processed means, and consumers are unable to accurately identify most ultra-processed foods when tested. Moreover, there is very low consistency between people when it comes to categorising foods as ultra-processed. This creates confusion and renders the system difficult to apply in practice.
Second, there is substantial disagreement and criticism of the system within food science. Criticism of the NOVA classification system highlights ‘major inconsistencies and mistakes’. As one criticism puts it:
“On the one hand, “yogurt with no added sugar or artificial sweeteners” is specifically cited as an example of a NOVA1 food. On the other hand, it is clearly stated that non-alcoholic fermentation, the process by which yogurt is made (i.e., lactic fermentation), is characteristic of NOVA3 foods. It is further mentioned that “substances […], such as casein, lactose, whey”—ingredients often present in yogurt—are “only found in ultra-processed products,” meaning NOVA4 foods.”
Similar examples of this kind of contradiction and inconsistency in the NOVA system abound, leading many food scientists to question its foundational approach.
Third, any time we categorise food into groups, we risk sweeping generalisations. Foods in the same group are then assumed to be equally good or equally bad, even though foods within a group can be very diverse. For example, we know that men are, on average, taller than women – but we all understand that this doesn’t mean that all men are taller than all women. Analogously, even if it is true that ultra-processed foods are less healthy on average, it can also be true that some foods which happen to fall into the ultra-processed category are, in fact, very healthy – such as wholegrain bread and fortified cereals.
The NOVA classification operates on the degree of food processing rather than specific nutritional content. This means that foods with a similar degree of processing, but with vastly different nutritional profiles may be grouped together, leading to oversimplifications. Categorising foods according to their degree of processing is not an informative way to analyse their healthiness when we have better data available. We can analyse the healthiness of foods directly based on their nutritional contents. Moreover, categorising foods according to this framework is the subject of public confusion and scientific contention, yielding this framework inconsistent.