Estimated time - 11 min

Not a week goes by without a new study blaming so-called ultra processed foods: these foods that were once called “junk food”, “bad food”, and which are now (relatively) better defined and characterized by consumers. Studies come from all countries, all continents: South America initially (Brazil in particular), but also Europe (France in particular, with the NutriNet-Santé study) and also North America (United States, Canada).

ultra processed food

Overall all the studies agree: ultra processed foods are associated -if they are observational studies-, or lead -if they are clinical intervention studies-, to metabolic dysfunctions, and ultimately diseases well known to Western societies : obesity, type 2 diabetes, cardiovascular diseases, .. It is important to insist on this concordance of the scientific corpus: because often, in human nutrition, scientific studies are contradictory, which makes nutritional recommendations difficult to establish. In the case of ultra processed foods, things seem clear, crisp and to the point.


Will ultra-transformation occupy a prominent place in the Clean Label of tomorrow? It is difficult to claim the opposite, as long as the clean label is an intrinsically vague concept and the definition of which varies according to the desires of consumers. The very intuitive opposition between real food and processed food can quickly gain ground in the minds of consumers, even though the concept of transformation is very poorly defined. To make matters worse, the ground is very well prepared in France: for several years now, smartphone apps have enabled everyone to decode the list of ingredients in a food at a glance, so that consumers are used  to use them when shopping. In fact, there are an estimated 22 million Yuka app users around the world. The two popular ultra-transformation classifications, NOVA and Siga, are referenced in the OpenFoodFacts (NOVA score), myLabel (NOVA score), Siga (Siga score), Scan’Up (Siga score) apps.

What about Yuka and the Nutri-Score ?

NOVA and Siga classify ultra processed foods

Neither Yuka nor the Nutri-Score take into account the degree of processing of the products, within the meaning of NOVA and Siga. These last two classifications rely on ultra-processing markers to recognize ultra-processed foods: some additives, but not all, are among these markers. In a way, Yuka could take this notion of ultra-processing into account in part, since it is the emphasis on additives that made the app famous; however, Yuka does not fully take this into account, since the other ingredients are not scrutinized.

ultra processed foods

Nutriscore doesn’t take ultra processed foods into account

On the other hand, the Nutri-Score, by focusing exclusively on macronutrients and fibers, seems totally out of the picture when taking ultra-processing into account. This situation is all the more problematic as, since the beginning of the 2010s, the scientific relevance of Nutri-Score has been highlighted. To the point of putting under media pressure agrifood companies who initially refused to apply the Nutri-Score, before complying for some. The perverse effect of reformulating according to the Nutri-Score rules is that it can potentially lead to ultra-processed food. Therefore, how should the latest opinion of the PNNS be interpreted which supports the nutriscore and now recommends a 20% reduction in the consumption of ultra-processed foods in the French population by 2022? This question without a clear answer illustrates the difficulties and uncertainties on the scientific level, but also on the level of food reformulation.

Mechanisms of action of ultra processed foods

How ultra processed foods act on human health ?

It remains to be explained how ultra-processed foods act on human health, so as to increase the prevalence of cardio-metabolic diseases (type 2 diabetes, obesity, cardiovascular diseases). In other words, what mechanism(s) of action make it possible to physiologically explain the correlations observed in observational studies? What in ultra-processed foods causes type 2 diabetes, cancer and cardiovascular disease? Beyond the purely scientific and academic aspect of this question, the final objective remains the physiological understanding of ultra-processed foods, to allow a relevant reformulation of NOVA 4 foods.

A reductionist approach

A detailed reading of observational studies incriminating NOVA 4 foods shows a reductionist approach independently from the speakers: researchers, founders of NOVA and Siga, but also PNNS. Unsurprisingly, additives occupy a prominent place, being ideal scapegoats despite a relatively meager body of science to be able to actually point them out as culprits. Moreover, the PNNS explicitly mentions this reduction in additives to combat ultra-processing. The “fat, sugar and salt” trio is also very popular, in particular to try to rehabilitate an increasingly criticized Nutri-Score. As for Siga, the establishment of a list of ultra-transformation markers (certain additives, protein isolates, processed sugars, refined oils, etc.) tacitly leads them to be considered as suspects, even if others mechanisms are being considered. In the end, a huge number of ingredients, additives and nutrients are pilloried but with a variety of mechanisms of action still poorly characterized.

Food intake is another interesting approach

Rather improbably, the only clinical intervention study incriminating NOVA 4 foods is diluted in the mass of observational studies; while this is the study with the highest level of evidence. This study, conducted by Kevin Hall in the United States in 2018, however suggests a mechanism much more powerful than the reductionist approach adopted so far, namely: food intake. NOVA 4 foods, because they are energetically dense and because they are quickly consumed due to their low satiating capacity, very quickly leads to an overflow of energy, which the body inevitably ends up storing in adipose tissue: it is exactly what the researchers observed, after only 14 days of a NOVA 4 type diet. This fat gain is very interesting: repeated over a lifetime, this is what potentially explains the low-grade inflammation, type 2 diabetes, obesity, cardiovascular disease, in other words explains all the findings of observational studies.


There is clearly a public health problem with ultra-processed foods, at least concerning foods classified as NOVA 4. The fact that all the studies on the subject point in the same direction is too rare a phenomenon in human nutrition. Ambitious public health policies are therefore expected.

ultra processed food

This alarming finding does not, at the same time, prevent us from scientifically questioning the causality, and therefore the mechanisms of action, of ultra-processed foods. According to the scientific corpus, and the associated level of evidence, it is the high energy density coupled with rapid consumption of these NOVA 4 foods that seems to explain most of the observed effects. The hype emphasizes a more simplistic reasoning, but not necessarily the most scientifically relevant, namely the responsibility for a wide variety of ingredients (additives, processed sugars, refined oils).

The agro-food industries, for their part, will have to examine with interest the rise in importance of the notion of ultra-processing, with a view to a new reformulation of foods. The task promises to be difficult, as the Nutri-Score is about to be accepted at European level. As mentioned, the two scores capture different information; everything will therefore depend on the attitude of the consumer.


Do you want to reformulate your food according to the different definitions of the clean label (additives, ultra-processed ingredients)? FOODINNOV experts can support you in this process:

If you would like to know more and discuss your project with one of our experts

Please contact us