Ask the Experts: What are ultra-processed foods and how do they impact our health?

Three UC Davis experts answer your questions to provide insight based on research

Diet. Just the word alone can trigger an uneasy feeling and heated discussions with seemingly endless flavors of recommendations. Over the years, Americans have shifted in our general approach to food based on evolving guidance. In the span of a few decades we have gone from the “eat less fat, cholesterol and salt” model to a heightened focus on reducing sugar consumption, and most recently towards eating more natural foods and avoiding those that are heavily processed.

Now we are hearing a lot about ultra-processed foods.

Many are confused, wondering what we should do and who we can trust.

A rapid sequence of actions added fuel to the discussion and concerns. Leading up to the national election of 2024, Robert F. Kennedy Jr., now the Secretary of the U.S. Department of Health and Human Services, raised concerns on the links between ultra-processed foods and chronic diseases. California Governor Newsom confirmed it to be a bipartisan issue with an order to ban several food additives. Soon after, the FDA banned red dye No. 3 from foods.

The rapid nature of this conversation and actions are raising a lot of questions and concerns.

To help clear up the confusion, we reached out to UC Davis experts in nutrition and food science, asking them to provide some clarity based on research.

Q&A

The term “ultra-processed” is new to many of us. Can you explain what it means and how it differs from other processed foods?

CHARLOTTE: “Ultra-processed food” or UPF refers to foods that are comprised of industrially produced ingredients and created through a series of industrial techniques and processed. It is a narrower and more specific category than “processed food,” which doesn’t have a clear meaning. Critics tend to argue that all processed food is bad and should be avoided, while advocates tend to argue that all food is processed, so attacking processed food is nonsensical.

The “ultra-processed” category was developed in 2009 by a group of Brazilian public health researchers led by Carlos Monteiro, as part of a classification system called NOVA that groups foods by extent and purpose of processing. The four categories are:

  1. Unprocessed and minimally processed foods, those we would think of as whole foods such as meat, produce and eggs.
  2. Processed culinary ingredients, or those used to prepare whole foods such as butter, oils and spices.
  3. Processed foods, or those foods made through combining the previous two groups and processing through preservation or cooking.
  4. Ultra-processed foods, or those made of industrially produced ingredients non-existent or rare in culinary use and created through a series of industrial processes. Includes soft drinks, many packaged snacks, mass produced breads and pastries, flavored yogurts, and instant soups.

It is helpful to keep in mind that the category was not designed to classify individual foods. The goal of the NOVA classification system is to provide a tool researchers can use to understand the health impacts of dietary patterns that include high percentages of ultra processed food.

 

Are there “good” and “bad” processed foods? Are there aspects we should be aware of that distinguish the two that we should consider when shopping?

Charlotte: Thinking about “good” and “bad” food in terms of processing, rather than nutrients, challenges the nutritional classifications that have long shaped dietary advice in the US (and elsewhere), such as MyPlate, which focuses on food groups and does not take processing into consideration at all. Many countries now use NOVA as the basis for dietary guidelines, including Brazil and France. In the process of determining the 2025 dietary guidelines for Americans the USDA has considered addressing processing, but appears not to be moving forward with any processing-related recommendations.

Nitin: Advancements in food technology and processing have played a vital role in enabling the development of safe food products with high nutritional quality and desired shelf life to improve food availability. Pasteurization technologies, including heat or high pressure (cold-pressed), significantly contribute to several nutritious food products’ safety and shelf life, including infant foods, fruit, vegetable- and dairy-based food products, and beverages.  Drying and freezing technologies, including spray drying, vacuum microwave drying, and individual quick freezing (IQF), play a key role in preserving foods and enhancing the availability and maintaining the nutritional properties of several seasonal food products. Furthermore, food packaging technologies, including barrier films and modified environment packaging, have significantly contributed to extending the shelf life, maintaining the nutritional properties of diverse food products, and reducing food waste.

Recent advances in food processing technologies to enhance environmental sustainability include significant efforts to electrify various heating and drying technologies. Examples include microwave and ohmic heating for pasteurization and sterilization of food products and ultrasound and microwave-assisted drying applications. Multiple technologies, including advanced heat pump technologies, are actively explored in research and industrial operations to capture waste heat from food processing operations.

 

What does research show in terms of the links to health-related diseases? Does this research point to specific aspects that we should look to avoid or consume more/less of?

Angela: There are two types of approaches used to establish links between food and health.  The first is intervention studies, which are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease. The second is observational, where people are asked to report on what they eat and then scientists take that information and apply statistical analysis techniques to explore associations with various health outcomes. As you can imagine, reporting an accurate inventory has many challenges…. people often either don’t remember or simply don’t admit to what they are truly consuming

The vast majority of research on ultra-processed foods (UPF) has been observational in nature. it may very well be the case that part of the reason for the strong links observed between the intake of UPFs and various disease outcomes is that these foods and diet patterns are particularly easy to account for with this approach. Another important point is that observational studies can only ever tell us about an “association” but not “causation.” This means that if we observe a positive association between the reported intake of a certain food or class of foods and a particular disease outcome, we are not able to know whether that association is actually being influenced by something else. For example, it could be the case that people who report eating more UPFs also vape more, drink more alcohol, are more food insecure and stressed, or exercise less. So we can’t really know from an observational study whether the association between the intake of UPFs and the disease outcome is caused by the intake of UPFs or if it is just one of the factors in an overall lifestyle that contributes to the increased risk for that disease.

In general, such studies found an associate between the intake of UPFs and obesity, cardiovascular health, some cancers, depression and gastrointestinal disorders.

There are very few intervention studies with UPFs. One study in only 9 overweight Japanese males showed that when assigned to UPFs the participants gained about 2 pounds more weight and consumed on average 800 more Calories per day over the course of one week compared to when they were assigned to non-UPFs (https://pubmed.ncbi.nlm.nih.gov/39267249/). A more robustly conducted intervention study in which 20 participants consumed UPFs vs. non-UPFs for 2 weeks in an in-patient setting also showed that participants consumed 500 more Calories per day when they were assigned to eat UPFs compared to when they consumed non-UPFs and similarly gained more weight (https://pubmed.ncbi.nlm.nih.gov/31105044/). In both studies the foods offered were matched for total content of carbohydrates, protein, fat, fiber, etc. and in both cases the participants were allowed to eat as much as they wanted. So these studies tell us that there is something about UPFs that makes us want to eat more and that including UPFs in the diet will likely lead to weight gain.

All that said, there are several key aspects about UPFs that we should all keep in mind. First, in general, UPFs are nutrient-poor, calorie-dense, very tasty/appealing or all of the above. Nutrient-poor foods are those that basically for every Calorie of that food that you eat you get very little in the way of nutrients (protein, vitamins, minerals, fiber, etc.). This is a problem because when you eat these foods you have consumed Calories but not any of the rest of what you need to be getting out of your food to sustain all of the various processes that the body needs to perform. When foods are Calorie-dense and particularly tasty it is easy to overeat and end up consuming more Calories per day than you need. Doing this consistently over time will lead to weight gain. So consuming UPFs has two main problems, one being that we can more easily overconsume Calories and thus gain weight, but also that we may be missing the nutrients that we would be getting if we were consuming nutrient-dense whole foods like fruits, vegetables, legumes, nuts, eggs, yogurt, chicken, fish, etc.

 

Are the links to diseases direct or indirect (via obesity or metabolic disorders)?

Angela: It is likely that the links between UPF consumption and disease outcomes are both indirect and direct. It is likely that both the excess Calories consumed leading to weight gain and metabolic disorders and the lack of nutrients (vitamins, minerals, polyphenols, etc) together contribute to the increased risk for a variety of diseases. It is also possible that certain ingredients in UPFs are particularly harmful in some individuals and groups. For example, the various artificial colors, flavors, stabilizers and preservatives used in many UPFs may also play a significant role in increasing disease risk, and this may be particularly the case for children, in whom the doses of these ingredients per pound of body weight are higher than in adults.

However, it is also important to point out that if one eats, say, 1 snack-size bag of chips with artificial flavors and colors once a month or less, it is extremely unlikely that these types of ingredients would have any negative health effects. On the other hand, if one eats a 1-pound bag of the same chips twice a day every day, now we are talking about potentially serious doses of these chemicals that may have a chance to accumulate and have measurable negative health effects. The dose makes the poison.

 

How do ultra-processed foods influence the gut microbiome? What is the importance/significance of this influence on physical and/or mental health?

Angela: There is little evidence from intervention studies and the only data that we really have are observational data. For any observations that have been found of an association between the intake of UPFs and negative outcomes related to the gut microbiome, we simply don’t know at this point how much of the problem can be attributed to consuming these foods vs. how much of the problem is due to NOT consuming healthy foods high in fiber and polyphenols, which are known to be beneficial for gut health.

 

Do ultra-processed foods affect people differently? If so, is that affect observed by age group, geographic location, socioeconomic levels, genetic factors, other?

Angela: We really just don’t have the answers to any of these questions yet. As mentioned previously, all we really have is hundreds of observational studies and reviews of those observational studies. What these tell us is that in those groups of individuals who consume large amounts of UPFs there is a slew of negative health associations. However, it is actually likely that all this points to more of a cultural and socio-economic problem more than differences between susceptibility to the effects of these foods between different groups of individuals.

I am personally fascinated by the fact that in the US today eating these UPFs has been completely normalized. It is now completely normal to see kids eating Cheetos and even candy as a “snack” at school. At the college level I see students eating pizza and burgers and fries from a fast-food restaurant as a “normal lunch.” Families eat out at fast food restaurants or other convenience locations as a “normal dinner.” These all used to be exceptions not the rule. American culture has drastically changed over the last several decades from one where home-prepared meals were normal and these convenience foods were a “special exception” or “special treat” to one where cooking at home is considered a hassle and many people consume UPFs for the sake of convenience, and perhaps even cost. I think it is a mistake to blame the UPFs themselves for the health problems they can cause. It is not these foods that are the problem it is their overconsumption and acceptance as normal foods that is at the heart of the problem, in my opinion. The problem with blaming the foods themselves is that it will only prompt the food industry to reformulate and it is not clear that this reformulation will lead to better outcomes. Instead, it appears to me that we need to fundamentally change our culture around food and in fact our perceptions about what is “food” vs. what is “edible entertainment.”

Food is supposed to “nourish” us, which means it needs to be delivering all the nutrients we need, from protein, carbohydrates, fiber and fat, to all the vitamins, minerals, and various other food components like polyphenols, that are known to be needed for a variety of metabolic and physiologic functions. It is not just a matter of adding these individual pieces to individual foods either because food companies cannot predict or control how much of any one product an individual might eat in a day. For example, I have some serious concerns about all of the various nutrient-boosted drinks out there. If people are drinking 5 vitamin waters per day they may be getting way too much niacin, for example, which was recently found to be associated with negative effects on vascular function when consumed in excess of the RDA. I am fascinated to hear Charlotte’s perspective on all of this as someone who thinks much more carefully about the relationships between culture and food.

 

Sources estimate that on average the diet in the U.S. are comprised of around 60-70 percent ultra processed foods. Why have we reached such high levels in the U.S.?

Charlotte: I completely agree with Angela that solving dietary health problems through product reformulations misunderstands the problem. The very definition of Ultra Processed food (intentionally) points us to the reasons why they are so widely consumed:

“Processes and ingredients used for the manufacture of ultra-processed foods are designed to create highly profitable products (low-cost ingredients, long shelf-life, powerfully branded). Their convenience (imperishable, ready-to-consume), hyper-palatability, and ownership by transnational corporations using pervasive advertising and promotion, give ultra-processed foods enormous market advantages. They are therefore liable to displace all other NOVA food groups, and to replace freshly made regular meals and dishes, with snacking anytime, anywhere.” (citation)

 

Product formulation may introduce more natural sounding ingredients, rearrange ingredients in new ways, or market products toward growing concerns about ultra processed food, but it does nothing to address the underlying reasons why ultra processed foods are so prevalent. At the same time, it doesn’t make sense to blame individuals for having diets so heavy in ultra processed foods; eating habits are shaped by their environments and UPFs are cheap, accessible, heavily marketed (including in schools and college campuses) and designed to be delicious (if not addictive – add link). according to NOVA, that is, precisely what makes them UPF!

Instead, we need to understand the systems and structures that shape our current food system. We have a farm subsidy system which has made corn and soy cheap to grow, a regulatory system that allows food companies to essentially self-govern the introduction of new additives and places very few limits on marketing, and market forces that require food companies to constantly deliver growth and profits. Changing the level of UPF in American diets will have to include regulatory and policy changes, not just product reformulation or dietary advice and education.

 

What explains the difference between ingredients used in food products in European countries vs. the United States? Is it local and/or federal regulations, market demand, cultural preferences, local and/or international supply chains, other?

CHARLOTTE: Europeans have long adopted the precautionary principle, which means that additives must be proven safe before they can be included in food. US food regulators have been unwilling to adopt this model, even though they have been pressed by consumer groups to do so. Instead, US food regulation is shaped by a “proof of harm” model that speeds innovation and supports business interests by making it much easier to introduce new ingredients, while placing the burden of navigating a potentially unsafe food environment on consumers (mainly women) (see Norah MacKendrick’s Better Safe than Sorry.)

 

What drives the use of such ingredients or processes (as well as trends)? Are they forced to decide between factors such as environmental sustainability, cost, taste, texture, and/or consumer health?

CHARLOTTE: Product development is a complex negotiation between the pragmatics of what is possible (materially and economically) and the pressures of consumer preferences, or trends. Since the early years of the 21st century food companies have been trying to develop and market products to appeal to consumer who want “real” food. As I write about in my new book, public attitudes toward processed foods have become increasingly negative due to a confluence of legitimate concerns about health, sustainability, regulatory laxity, and the appropriation of scientific authority by the food industry. Products that are labelled “natural,” have short ingredients with only words you can pronounce, or are covered in “free from” claims may appeal to consumers, but they cannot address the larger concerns about food, the food industry and the food system that have shaped the idea that good food is “real.”

 

Do you encounter any common “myths” about ultra processed foods that can be dispelled by your research or by other research done in your field of study?

CHARLOTTE: A common myth among experts in the food industry and related sciences is that the public is concerns about processed / ultra processed food because they don’t understand the science behind processing and are irrationally fearful of things they don’t understand. These assumptions have shaped all kinds of education and information campaigns aimed at building trust by educating the public about the benefits of processed food (can link to the book, or directly to examples of this, or we could embed this graphic, with a little explanation of how it illustrates this). From my point of view, this is a misunderstanding of the public and – its reasons for being skeptical about processed food and other food system technologies – that leads to greater, not less alienation and mistrust. (happy to say more here if you like this direction).

Nitin: Most of the debate about ultra-processed foods focuses on ingredient and formulation concepts, and the role of processing technologies in terms of food classification is not well established. Research is needed to clearly understand the individual roles of ingredient formulations and processing in influencing food properties and their impact on human health.

 

How would you describe the role of “trust” between consumers, regulators, food growers and manufacturers, and health care providers?

CHARLOTTE: The food industry recognizes that consumer trust is waning and sees this as a problem manufacturers must address, particularly if they want to continue to operate with minimal restrictions, or regularly hurdles. The work of building trust with consumers has largely been taken on by trade associations, such as the International Food Information Council (IFIC), and “front groups” (ie those working on behalf of industry while claiming to be impartial) such as the Center for Food Integrity.  For example, IFIC started an organization called the Alliance to Feed the Future that developed a curriculum for k-8 grades promoting the benefits of “modern food processing” and processed foods. Concerned that traditional, facts focused efforts like these are no longer working, the Center for Food Integrity develops and disseminates new models based on “transparency” and “shared values.” My research suggests that all of these efforts fail to address the underlying questions and concerns of the public, which have to do not just with health and safety but also the aims and trajectory of the food system itself, and the power dynamics that shape the kinds of questions that seem reasonable to ask about food as well as the kind of expertise that is deemed relevant to answering questions about food. (can add links)

 

What technological advances are (or will likely) changing the complex landscape of ultra-processed foods?

Nitin: Ingredient formulations play a significant role in the classification of foods as ultra-processed food products. Many of these ingredient formulations are selected to create specific textures or structures, for example, the use of emulsifiers and stabilizers to stabilize dispersed oil in water systems or enhance the mouthfeel of the food products. Similarly, food ingredient formulations may include preservatives to maintain the shelf life and nutrient content of foods. In certain products, the selection of specific artificial colors may be based on the requirements to maintain the color of products during the heating or cooking of foods.

Based on technological advances, novel structuring or texturization processes may be developed to reduce the requirements of emulsifiers and stabilizer ingredients in food products. Similarly. advances in both food packaging and processing technologies may reduce the reliance on preservatives to maintain the shelf life and nutritional properties of food. Furthermore, advances in food chemistry and processing may enable the selection and stabilization of natural colors in food products.

In addition, the current classification approaches for ultra-processed foods have not clearly described the role of the ingredient formulations and processing technologies in impacting the nutritional and health aspects of food. Research is needed to clearly understand the individual roles of ingredient formulations and processing in influencing food properties and their impact on human health.

 

In what ways might AI play a role in the food processing system moving forward? Is the use of AI limited to food growers, manufacturers, consumers, doctors, or researchers?

Nitin: Digital information about food systems and their analysis with AI models are expected to play a significant role in advancing food processing systems. These roles may include AI-enabled digital twin technologies for enhancing consistency and efficiency in food production.  Similarly, advances in AI-assisted bio-analytical technologies will improve food safety and the quality of food products, as well as reduce the cost of implementing regulatory requirements. AI-enabled analysis of food systems, including food by-products, may significantly enable us to improve the sustainability of food systems, recovery of vital nutrients from food by-products and reduce food waste. Similarly, AI-enabled analysis of food composition and structure and their integration with food digestion is expected to improve the nutritional and health impacts of food. Thus, the applications of AI in food systems are expected to connect food growers, manufacturers, consumers, researchers, and medical professionals and result in improved food safety and nutrition and reduce food waste.

 

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