By Mahes Muniandy

Research has shown that ultra-processed foods (UPF) is associated with all-cause mortality and several health conditions, including cardiovascular and mental health diseases (Lane et al., 2024). While it has long been known that UPFs are not the healthiest food options, most people struggle to make the switch to healthier food options. Indeed, in the US and UK, UPFs make up a staggering half of the daily energy intake (Henney et al., 2024). In Finland, this number is 41% (Monteiro et al., 2018).

The term UPF instinctively leads us to believe processing, and lots of it, is the enemy here. But it turns out, most food is processed. The NOVA classification system considers, instead, both the degree and purpose of the processing. This classification system includes four incrementally processed groups: (1) unprocessed or minimally processed food, (2) processed culinary ingredients, (3) processed food, and (4) ultra-processed food (Monteiro et al., 2019). So, a tomato that’s been washed belongs to group 1 and bread made from flour that has been milled belongs to group 3. Both have been processed, albeit to differing degrees. To clarify the term UPF, Chris Van Tulleken in his book “Ultra-processed people” says: “The presence of ingredients that you do not have in your kitchen is an indicator of UPF”.

So how did UPF invade our lives so completely? It all started rather unsuspectingly with human civilization. As Van Tulleken clarifies, processing food started barely a million years after humans diverged from chimpanzees. Beyond a few wild berries, oysters, raw milk and mushrooms, most foods are indeed processed. Picking meat off a mammoth carcass, cooking with fire, genetically modifying crops and animals by breeding them selectively? –– all processed foods (Van Tulleken, 2023). Starting from this simple processing, UPFs developed progressively, all to meet various needs that arose over time.

Presently, UPFs seem to have infiltrated our lives quite thoroughly and with reason. On the one hand, food manufacturers achieve longer food shelf-life and often-times cheaper production and distribution. Van Tulleken offers up the example of ice cream that doesn’t melt while being transported for long hours in trucks. Consumers, on the other hand, get food that looks appealing and tastes good. Think cake, fries and hamburgers, what’s not to love? As if we needed any further encouragement, they make life so easy –– few people want to cook wholesome minimally processed food from scratch after a long day’s work or studying. Beyond these practicalities, humans also seem to have an instinctive pull toward UPFs. The brain easily detects the degree of processing in foods, as early as 130 milliseconds in (Coricelli et al., 2019).

Even if you are actively seeking healthier options, there can also be some difficulty in differentiating between a UPF and non-UPF. Is bread baked at home less processed than bread bought at the bakery –– probably not, if the bakery is getting the flour from the same place as the home baker. What about when UPF is the better option? For example, tomato paste has more beta carotene than tomatoes. Meat alternatives are free of animal-cruelty and much more sustainable. So which option should one get?

And so, we turn to research to show us the way. Unfortunately, research on UPFs has proven to be challenging. Knowledge about the exact components in UPFs that are associated with adverse health has remained elusive. It’s clearly not the high sodium, high fat content – some UPFs are low in fat and sodium but are still a UPF. There is also a lack of understanding of the exact mechanism that links UPF with adverse health outcomes. Potential mechanistic pathways include altered gut microbiota composition and function, degradation of the food matrix, contaminants from food packaging (e.g., bisphenol), and food additives. Association studies on UPFs face confounding from socio-economic factors and reverse causation, while epidemiological study results have mostly focused on processed meat and sweeteners and not on other UPFs. If all this research isn’t daunting enough, some research-backed evidence is vilified on social media. Let’s take seed oil, which evidence has shown to be a better alternative to non-seed oil. “UPFs use seed oil, so seed oil is bad” is a common argument prevalent on social media.

But wait, there’s another hurdle beyond the research. Once we figure out what in UPFs is detrimental to our health, we need to figure out what to do with this information. Different countries have different ways of providing dietary guidelines. Brazil was the first to emphasize UPFs in their dietary guidelines instead on focusing mainly on nutrient content. Because NOVA classification is a research tool, not a policy tool, it’s up to the different countries on what the guidelines should be. Interestingly, a study of guidelines from 137 countries found that nutrient-based messages seem to be more common than messages about processing levels (Zheng et al., 2022).

It’s clear that the confusion around UPFs is going to continue to baffle us for a while yet. While we look to improved nutritional guidelines to communicate the concept of ultra-processing in consumer-friendly formats, what do we do in the meantime? Most people seem to be aware that UPFs do more harm than good. Perhaps the simplest way out is indeed to just ask ourselves “How many of the ingredients listed on the food label are available in my kitchen?”.

Mahes Muniandy,
Biostatistician and Obesity Researcher,
Obesity Research Unit,
Research Program for Clinical and Molecular Metabolism (CAMM),
Uni. Helsinki

References:

Coricelli, C., Toepel, U., Notter, M.-L., Murray, M. M., & Rumiati, R. I. (2019). Distinct brain representations of processed and unprocessed foods. European Journal of Neuroscience, 50(8), 3389-3401. https://doi.org/https://doi.org/10.1111/ejn.14498
Henney, A. E., Gillespie, C. S., Alam, U., Hydes, T. J., Boyland, E., & Cuthbertson, D. J. (2024). Ultra‐processed food and non‐communicable diseases in the United Kingdom: A narrative review and thematic synthesis of literature. Obesity Reviews, 25(4), e13682.
Lane, M. M., Gamage, E., Du, S., Ashtree, D. N., McGuinness, A. J., Gauci, S., Baker, P., Lawrence, M., Rebholz, C. M., Srour, B., Touvier, M., Jacka, F. N., O’Neil, A., Segasby, T., & Marx, W. (2024). Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ, 384, e077310. https://doi.org/10.1136/bmj-2023-077310
Monteiro, C. A., Cannon, G., Levy, R. B., Moubarac, J.-C., Louzada, M. L., Rauber, F., Khandpur, N., Cediel, G., Neri, D., & Martinez-Steele, E. (2019). Ultra-processed foods: what they are and how to identify them. Public health nutrition, 22(5), 936-941.
Monteiro, C. A., Moubarac, J.-C., Levy, R. B., Canella, D. S., da Costa Louzada, M. L., & Cannon, G. (2018). Household availability of ultra-processed foods and obesity in nineteen European countries. Public health nutrition, 21(1), 18-26.
Van Tulleken, C. (2023). Ultra-processed people. WW Norton.
Zheng, K., Gao, W., Cao, W., Lv, J., Yu, C., Wang, S., Huang, T., Sun, D., Liao, C., & Pang, Y. (2022). Education, income, and obesity: A nationwide Chinese twin study. Obesity, 30(4), 931-942.