Ultra-processed foods: true villain or just misunderstood?

It’s all anyone talks about but what are ultra-processed foods exactly?

Processing occurs on a spectrum, with the commonly accepted mischief makers, ultra-processed foods (UPFs) falling at the extreme. To define them, the Nova classification system is most often used. It categorises foods into four categories with UPFs in Group 4 on the right below. (Ref)

‘Source: Crimarco, Anthony & Landry, Matthew & Gardner, Christopher. (2021). Ultra-processed Foods, Weight Gain, and Co-morbidity Risk. Current Obesity Reports. 11. 1-13. 10.1007/s13679-021-00460-y, adapted from Monteiro et al. (2018)

The originator of the Nova system, Brazilian academic Carlos Montero defined them thus:

“Ultra-processed foods are formulations of ingredients, mostly of exclusive industrial use, that result from a series of industrial processes….Colours, flavours, emulsifiers and other additives are frequently added to make the final product palatable or hyper-palatable. Processes end with sophisticated packaging, usually with synthetic materials.” (Ref)

Maybe you already see the problem. It’s not always clear which category some foods fall into. The consumer isn’t usually privy to the processing a food has undergone, while ingredients are often listed as numbers, many of which are garden-variety foods, for example, 100 is the code assigned to a yellow food colouring, though you might know it as turmeric. (Ref) Even experts are inconsistent when asked to categorise various foods into NOVA groups, (Ref) suggesting a practical shortcoming.

Still, we’re all eating an awful lot of UPFs

Even allowing for some grey area, a 2012 Australian survey found we obtained some 42% of our calories from UPFs (and this likely undershoots the figure thirteen years later). (Ref)  A European population study found intakes ranged from 16% of daily calories in Italy to 45% in Denmark; (Ref) while research in the US suggested 56% of Americans’ energy came from UPFs. (Ref)

More UPFs  mean more health problems

And as UPF consumption increases, so do health problems. A 2024 review of observational studies found associations with cardiovascular disease, type 2 diabetes, breast and colorectal cancers, anxiety and mental health conditions, poor sleep and obesity. (Ref)

The European population study mentioned above also found links to cancer, heart disease and type 2 diabetes. Interestingly though, it found UPF animal-based foods; and soft drinks (sugar and artificially sweetened) had the strongest associations; while UPF breads and cereals were protective (though this is such a broad group that it’s hard to be precise); and UPF plant-based meat alternatives were also borderline protective. Meanwhile, other UPF categories were roughly neutral. (Ref) This detail is important, suggesting as it does that not all UPFs are unhealthy and perhaps that processing per se is not the main issue. This is also the conclusion that the Scientific Committee for the American Dietary Guidelines reached (See this article).

These are all observational studies though! Well yes, interventional trials are thin on the ground to date. Perhaps the best trials have been conducted in examining the effects of UPFs on weight and body fat. And amongst these trials, by far the most cited must be Kevin Hall’s feeding trial that compared UPFs against minimally processed foods (MPFs) with participants allowed to eat as much as they desired of their assigned diet. (Ref) The results were telling: participants ate a, not insubstantial, 500-odd extra calories daily on the UPF compared to the MPF diet and gained roughly as much weight and body fat after two weeks eating UPFs, as they lost eating MPFs. At the same time, blood cholesterol and inflammatory markers, both indicators of chronic disease, rose significantly with the UPF compared to the MPF diets, supporting the theory that UPFs cause these diseases.

So what makes UPFs unhealthy?

Reason 1 - Hate the game not the player: Gimme, gimme shiny food!!

UPFs don’t happen naturally: they’re invented, and rarely with purely philanthropic intent – that is, they’re there to make money. We may buy UPFs because they’re ready-to-eat; for their low-maintenance, pantry-dwelling properties; or just for the cool-factor. Whatever the core need, it makes sense to edge out competition by making each UPF more tasty than the last, leading many a rational, profit-seeking manufacturer, to add sugar, salt and fat which, though linked to disease (Ref, Ref, Ref), are all cheap and tasty (and, handily, also extend shelf-life). (Ref) While they’re at it, fibre is minimised since it slows eating rate and makes food more filling, and that’s not going to help sales! True, these factors are not unique to UPFs but UPFs are just everywhere and a yen for a tasty food treat (perhaps prompted by a well-placed UPF cue) need rarely go unanswered. The 2012 Australian dietary survey did indeed find that saturated fat, sugar and salt increased with UPF consumption, while fibre decreased, to suggest we were in fact seeking out the tastiest UPF options and that our UPF habits were harming our health. (Ref)  

Reason 2 - The opportunity cost of the road untravelled

Eating half our food as UPFs, implies eating a lot less minimally processed food. With UPFs, nutrition isn’t really the point, unless it can be used to make a nutrition claim on the pack to drive sales - something that is quite tightly regulated by Food Standards Australia New Zealand (FSANZ). By definition, UPFs are assemblies of stripped-down components, with healthy elements that detract from sensory properties, such as bitter tastes or tough fibre, extracted directly, while remaining vitamins, minerals, and biologically active compounds may well be lost during chemical and physical processing along the way. Displacement of these beneficial components may well cause equivalent harm as excesses of salt, sugar and fat.  

Reason 3 - Bad chemicals. Maybe.

Additives, whether included to preserve food in a box-fresh state, or enhance appearance, taste or texture, have been tested by FSANZ and their use permitted only with a wide margin for safety. However, it’s also true that permissions are revoked from time to time as new evidence emerges. It may also be the case, that some additives, though not overtly harmful, run interference to the long-term detriment of health, which may be even harder to pick up if it’s only a subgroup of susceptible people who are affected. For instance, several food dyes show adverse effects on some children’s behaviour; (Ref) while carboxymethylcellulose, a common emulsifier, is suggested (and little more than that) to be implicated in gut inflammation in predisposed people. (Ref)

There are also several additives which are more restricted overseas than in Australia. (Ref) While FSANZ explains its rationale for including these, it’s a potential caveat. Here’s a full list of all permitted additives.

Reason 3 - Food matrix adulteration. Seems so, yes.

The food matrix? That is, the structure of nutrients in food. An undisturbed food matrix usually requires more chewing and internal digestive fire power for the body to gain access to the nutrients, which promotes fullness through both greater food volume (fibre and water) and longer eating time, while also shielding some of the calories from digestion and so reducing caloric load. This was one reason suggested for the findings in the Hall study. So, for example, compare peanuts (intact matrix) and peanut butter, where the peanut cell walls have been pulverised to release the fats and and make it a more compelling proposition. Many cereals have fibre stripped away to deliver a product that needs a lot less chewing - think about the jaw workout delivered by brown rice compared to white. Or, juices have all the fun stuff (sugar) without a lot of the boring fibre (or peeling, chopping and chewing). While none of these examples would qualify as UPFs just because the matrix was meddled with, they do illustrate humans’ desire for an effortless calorie and, of course, this is something that any right-thinking profit-seeking food producer would seek to deliver.

Conclusion

So where does this leave us? UPFs themselves aren’t always easy to identify and the properties that may make them harmful (a surfeit of unhealthy elements coupled with a lack of improving components,  additives with dubious health impacts plus modification of the food matrix) are not unique to UPFs. Rather the problem seems to be one of magnitude brought about by the constant prompting to consume products explicitly designed to override our more sensible selves, entailing much reward and little work and crowding out more nutritious (yet, less alluring) options. In short, we are victims of our own biology, abundantly enabled by a free market economy. This combination of factors implies we might need saving from ourselves through regulation, where the evolution of smoking restrictions may be extended as a template. Any such suggestion has been resisted in Australia to date, though several examples from around the world provide cause for optimism. This, however, is a subject for a separate article.