March 2025 Issue
Great Debates: Ultraprocessed Food
By Carrie Dennett, MPH, RDN
Today’s Dietitian
Vol. 27 No. 3 P. 20
Are these polarizing foods helpful, harmful, or both?
The argument that ultraprocessed foods (UPFs) are harmful to health has been building for the past 15 years, heightened recently by some key events. Late last year, the Dietary Guidelines Advisory Committee came under fire for indicating that there wasn’t sufficient evidence to recommend reducing or avoiding UPFs.1 Shortly after that, lawyers filed a lawsuit against 11 multinational food companies on behalf of a Pennsylvania teenager who says he developed type 2 diabetes and fatty liver disease as a result of consuming UPF.2,3
One of the lawsuit’s claims is, “The explosion and ensuing rise in UPF in the 1980s was accompanied by an explosion in obesity, diabetes, and other lifechanging chronic illnesses.”3 Among the evidence cited is the 2023 book Ultra-Processed People: The Science Behind the Food, by British doctor Chris van Tulleken, who increased his usual UPF intake from 30% to 80%—including sugary cereal, soda, chips, and fast foods—for four weeks. He gained weight, reported constant cravings for UPFs, and said he felt 10 years older.4,5
A 2022 study6 using data from the National Food and Nutrition Examination Survey estimated that Americans consumed an average of 58.2% of calories from UPF as defined by the NOVA classification system, the most commonly used scale for classifying foods by degree of processing. But does NOVA fully capture what makes a food healthful? And does the current body of evidence on UPF support claims that it is a prime culprit in chronic disease?
What Does “Ultraprocessed” Mean?
The term “ultraprocessed” was coined by Brazilian epidemiologist, Carlos Augusto Monteiro in 2009.7 In 2010, he and his research team presented the NOVA scale,8 which classifies foods into four groups depending on their degree of processing. Group 1 foods are unprocessed or minimally processed, with no added salt, sugar, oils, or fats. They may be fresh, frozen, dried, or ground. Group 2 are processed culinary ingredients, including salt, butter and lard, corn starch, sugar, molasses, honey, maple syrup, olive oil, and seed and nut oils.9,10 Group 3 foods are processed, and typically Group 1 foods with sugar, oil and/or salt added to increase shelf life or enhance taste. These include canned vegetables, fruits, and beans; salted, cured, or smoked meats; canned fish; fruits in syrup; cheese; and freshly made breads.
UPFs are in Group 4, and include most foods and beverages produced by the food industry because all foods containing at least one marker of ultraprocessing are automatically placed in this group. These markers include food processes such as extrusion cooking, molding, and prefrying, as well as ingredients not traditionally used in culinary preparations or with no domestic equivalents,11 including ingredients used to modify color, aroma, taste, or texture.11,12
While this group includes chips, candy, and sugar-sweetened beverages, it also includes enriched grains, such as breakfast cereal, snack bars, and mass-produced breads. “Taking those out of the diet of at-risk populations would result in lower intake of iron and several B vitamins13 that are especially important for women in their reproductive years,” says Boston-area writer and nutrition consultant Elizabeth Ward, MS, RDN. “Including folic acid in enriched grains was a public health milestone.”
Group 4 also includes plant-based cheese and meat substitutes, tofu, tempeh, and soy milk.14 Taylor Wolfram, MS, RDN, LDN, a Chicago-area dietitian in private practice, says classifying even calcium-fortified unsweetened organic soy milk as a UPF is problematic. “It’s a rich source of calcium and vitamin D, and it’s difficult for vegans to meet the DRI for calcium on whole plant foods alone. If people are trying to eliminate ultraprocessed foods, they’re eliminating major calcium sources by eliminating plant milks and calcium-set tofu. Soy is also a great source of protein and an important source of choline, which can be tricky to find in a plant-based diet.” A 2023 study found that vegans who consume less UPF were more likely to have inadequate protein intake.15 “For a lot of people, eating several servings of whole legumes a day, which is what would be recommended for a vegan who’s not eating any plant meats, just isn’t realistic.”
Infant formulas, nutritional drinks and shakes, and enteral formulas used for tube feeding are also classified as UPF. “If we are dietitians and saying, ‘Don’t eat ultraprocessed foods,’ I think we don’t recognize that we recommend that people eat ultraprocessed foods all the time,” says Sacramento, California-based dietitian Jessica Wilson, MS, RD, author of It’s Always Been Ours: Rewriting the Story of Black Women’s Bodies and host of the Making It Awkward podcast. “We know [NOVA] was not made by a clinician or anyone who’s actually had to talk to somebody about food, and processing of food can often be a good thing. We’ve developed a lot of these ways of processing foods to make them safer and more shelf stable. In this country we’re not all going to be able to buy fresh fruits and vegetables, and as dietitians, we know that things don’t lose all their nutrient value when they’re canned or when they’re frozen. But nobody puts that together.”
Marie Spiker, PhD, RDN, an assistant professor in the University of Washington School of Public Health in Seattle, points out that UPF can fill important gaps. “There are occasions where you really need something that’s convenient, fast, or shelf stable,” she says, such as for people who don’t have consistent access to refrigeration or schools that send students home with food for the weekend through a backpack program. “A student might not get home for a few hours, so in this situation it’s important to stick to nonperishables for food safety reasons.” She also notes the infrastructure challenges faced by hunger relief organizations. Perishable foods are highly desired, but cold storage is costly.
Nutrients vs Processing
Wilson says she hears a lot of, “Canned tuna, canned chicken, aren’t those unhealthy?” even though they’re Group 3 foods. “Many people can’t hold the complexity of processing. It’s easy to simplify and collapse all processed foods into one so we don’t know if we’re talking about black beans in a can or if we’re talking about Cheetos.” In fact, under the NOVA classification system, many nutritious foods are in the same category as foods with few nutrients. This raises a question of whether it’s the processing or the nutrient density we should be concerned with when it comes to chronic disease prevention.
A 2023 review16 argued that while there needs to be some form of classification of “processing” and “ultraprocessing” to help guide public health policies, these terms are ill-defined, and NOVA’s UPF classification has repeatedly changed for unclear reasons. The authors said NOVA conflicts with evidence-based evaluation of foods because it claims that how the food is produced is more important than the food itself or how much of it is consumed. Also, NOVA factors in the assumed “purpose” for which companies design and produce UPFs—to create branded, convenient, hyperpalatable and highly profitable food products. This introduces a subjective, possibly ideological bias to the food classification process.
In response to van Tulleken’s experiment, Wilson did her own month-long UPF experiment in 2023. She swapped eggs for soy chorizo at breakfast and replaced her thrown-together lunches with ready-to-eat tamales or other meals. She snacked on cashew milk yogurt with granola instead of grabbing a spoon of peanut butter. Dinners included premade pupusas—thick masa tortillas stuffed with meat and cheese—or chicken sausage with canned vegetables and tater tots.17 She said she felt fuller and had a better mood and more energy, possibly because she was eating an actual meal at lunch, had more readily available calories, and stressed less about what to eat.
For a 2023 proof-of-concept study, USDA scientists created a seven-day, 2,000-calorie diet with 91% of calories coming from NOVA-defined UPFs and a Healthy Eating Index of 86—a score of 100 meets all Dietary Guidelines for Americans (DGA) recommendations, while the average score among American adults is 59. The study diet aligned with all DGA recommendations except for sodium and whole grains.18,19 Conversely, the same group created a version of the nutrient-poor “Standard American Diet” using less-processed foods in place of more-processed foods, such as white bread that was scratch-made instead of mass-produced. They found the less-processed diet was not more nutritious, was more expensive, and had a shorter shelf life—in short, the NOVA classification alone does not guarantee a high-quality diet.20
“Lumping foods such as orange cheese curls with things like tofu and tempeh and seltzer water, and saying that all ultraprocessed foods are bad for you, is dangerous and silly and confusing,” Ward says. “I think the whole problem with the NOVA system is that it ignores nutrition entirely, it subjectively puts these foods in certain categories.” She says NOVA’s main flaw is that it puts nutritious, affordable foods such as peanut butter and enriched grain foods, along with foods such as protein powder that can help people with small appetites, in the ultraprocessed category.
The Evidence on UPF
The evidence base linking intake of UPFs to adverse health outcomes is almost exclusively based on observational studies with small effect sizes that don’t always control for confounders. Systemic reviews and meta-analyses of these studies from the past few years have found associations between higher intake of UPF and increased risk of metabolic disease;21 cardiovascular events and all-cause mortality; 22,23 multiple sclerosis, Parkinson’s disease, and cognitive impairment;24 dementia;25 depression;26 colorectal cancer, colon cancer, and noncardia gastric cancer;27 gestational diabetes;28 chronic29 and incident30 kidney disease; chronic insomnia;31 and biological aging.32
However, one 2024 review of UPF-cardiometabolic risk associations noted that the quality of the evidence was “not satisfying,” and the level of risk changed by as much as 50% depending on the methodology used to assess UPF intake, suggesting caution when interpreting and extrapolating the results.33 Similarly, a 2024 umbrella review involving almost 10 million people found associations between UPF intake and 32 health parameters. However, while there was convincing, moderate-quality evidence to support an association between UPF and type 2 diabetes risk, all other evidence was of low or very low quality and/or had a credibility of highly suggestive, suggestive, or weak.34
Recent analyses of data from the Nurses’ Health Studies and Health Professional Follow-Up Study found positive associations between total UPF intake and cardiovascular risk35 and type 2 diabetes risk36 in US adults, but inverse associations between cardiovascular and diabetes risk and intake of certain UPF subgroups, including bread, breakfast cereals, sweetened yogurt, dairy desserts, and savory snacks. The current Dietary Guidelines Advisory Committee found limited evidence that higher-UPF dietary patterns were associated with higher fat mass, waist circumference, or BMI. There was insufficient evidence, or consistent evidence, to make any statement about UPF and infants and young children, pregnant people, or postpartum adults.1
One issue is that there have been only two randomized controlled trials—both small, short, cross-over metabolic ward studies—investigating the effects of UPFs, but only on weight gain.37,38 Both trials found that participants consumed more calories and gained weight on the UPF diet, although there was a steady, significant decrease in calorie intake across the course of the UPF diet arms. The often-cited National Institutes of Health study37 did not control for macronutrient profile and therefore calorie density, which is known to have a strong effect on weight gain.39 Participants also received supplemental soluble fiber on the UPF diet, whereas they consumed a wider variety of fiber on the unprocessed diet.
Mechanisms of Risk
Another research gap concerns biological plausibility. If UPF causes poorer health, what are the mechanisms? Proposed mechanisms include hyperpalatability, higher energy density, promotion of a faster eating rate,40 gastric emptying time, impact on the gut microbiome, the ability to stimulate hunger and suppress fullness,41 the presence of contaminants or certain food additives, and the high-heat treatment of many UPFs.40,42,43 Another study proposed that UPFs may be addictive.44
A 2021 study looked at mechanisms that might explain associations between UPF intake and CVD risk,45 emphasizing the role of added sugar and sodium and lack of dietary fiber, and the possibility that UPFs displace fruits and vegetables in the diet. However, the authors primarily cited studies on Western-style diets, not UPFs per se, as well as animal studies. A 2023 review of proposed mechanisms that might explain UPF-weight gain associations found no evidence directly linking UPFs with increased BMI.41
Another proposed mechanism is degradation of the food matrix—the chemical and physical components of food plus their molecular relationships which affect how food is digested and metabolized—on health. The authors of a 2024 review argue that the food industry should respond to concerns about UPFs not by reformulating them—replacing one ingredient or process for another—but by developing less-processed industrialized foods with better ingredient quality and more preserved food matrices.12
Potential Effects of Eradicating UPFs
A 2022 study authored by NOVA’s creator stated that despite not knowing the mechanisms by which UPF could harm health, existing evidence is sufficient to recommend the avoidance of UPFs to optimize health.46 As the time of writing this article, potential political appointees were talking about eliminating UPFs from schools and elsewhere in the food system. What could be the resulting impact?
“All of the people who don’t have time for meals are not going to eat them,” Wilson says. “Or, to feed a family, somebody’s going to have to give up at least part of their workday in order to cook for five people or however many people are in their home.”
Shana Minei Spence, MS, RDN, CDN, Brooklyn, New York-based author of Live Nourished: Make Peace With Food, Banish Body Shame, and Reclaim Joy, points out that many people are working more than eight hours a day and often more than one job. “Overall, we need convenience foods because we do not have the quality of life or work-life balance as other places to accommodate home cooked meals,” she says. “Until we start acting like European countries and shutting down for meals completely and getting adequate time off work, we will need convenience foods. Not to mention that there will always be folks with disabilities who cannot cook from scratch and need convenience foods.”
Wilson thinks there could be a return to parental and clinical intolerance of children who don’t or won’t eat what is served for dinner. “Now, if kids are going to eat something, I think a lot of parents realize that something is better than nothing” Wilson says. “And we’ll start policing people even more than we do right now for not being able to breastfeed their child. And if they can’t feed them formula, they don’t go back to work.”
Ward finds the laser focus on certain processing methods interesting. “It seems like it’s uncorked some rage about our food. But processed foods are here to say. Let’s learn how to deal with them. Let’s teach consumers how to evaluate a food on its own merits.”
— Carrie Dennett, MPH, RDN, is the nutrition columnist for The Seattle Times, owner of Nutrition By Carrie, and author of Healthy for Your Life: A Non-Diet Approach to Optimal Well-Being.
References
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