From breakfast cereals and protein bars to flavored yogurt and frozen pizzas, ultraprocessed foods are everywhere, filling aisle upon aisle at the supermarket. Fully 58 percent of the calories consumed by adults and 67 percent of those consumed by children in the United States are made up of these highly palatable foodstuffs with their highly manipulated ingredients.
And ultraprocessed foods are not just filling our plates; they’re also taking up more and more space in global conversations about public health and nutrition. In the last decade or so, researchers have ramped up efforts to define ultraprocessed foods and to probe how their consumption correlates to health: A wave of recent studies have linked the foods to heightened risk for conditions ranging from cardiovascular disease and cancer to obesity and depression.
Still, some researchers—and perhaps unsurprisingly, industry representatives—question the strength of the evidence against ultraprocessed foods. The category is too poorly defined and the studies too circumstantial, they say. Plus, labeling such a large portion of our grocery carts as unhealthy ignores the benefits of industrial food processing in making food affordable, safe from foodborne pathogens, easy to prepare and in some cases more sustainable—such as through the development of plant-derived products designed to replace meat and milk.
“You cannot throw the baby out with the bathwater and decide that you’re going to just dump everything” that’s ultraprocessed, says Ciarán Forde, a sensory science and eating behavior researcher at Wageningen University in the Netherlands and coauthor of a 2022 look at food processing and diets in the Annual Review of Nutrition.
As the debate about ultraprocessed foods roils on, one path forward is to invest in understanding the mechanisms by which ultraprocessed foods affect health. If the foods are indeed harmful, what about them—what features?—makes them so, and why? Through feeding volunteers carefully formulated diets and watching their consumption behavior, researchers can identify the qualities that make these foods both so appealing and so unhealthful, they say. Such studies could help to pinpoint the most harmful types of ultraprocessed foods—ones that might be targeted with warning labels and other policies—and guide companies in tweaking their recipes to produce more healthful options.
“I think the biological mechanisms are really important both to strengthen the evidence, but also to find solutions,” says Filippa Juul, a nutritional epidemiologist at New York University. That said, Juul adds, she thinks there’s already enough evidence about the harms of ultraprocessed foods to recommend that people eat less of them.
Sifting the evidence on ultraprocessed foods
To study ultraprocessed foods, researchers must be able to define them, and even this is contentious. Food preparation involves processes like grinding, cooking, fermenting and pasteurizing — methods that have long been used to make foods safer and more digestible, palatable and storable. But according to the most widely used classification system, called NOVA, ultraprocessed foods are distinguished by additional industrial techniques, like hydrolysis, hydrogenation and extrusion, and with ingredients like emulsifiers, thickeners, flavors and other additives that are rarely found in home kitchens.
|Industrially manufactured food products made of several ingredients including sugar, oils, fats and salt (generally in combination and in higher amounts than in processed foods) and substances of no/rare culinary use (such as high-fructose corn syrup, hydrogenated oils, modified starches and protein isolates||All carbonated soft drinks; “fruit” drinks and energy drinks
|Industrial techniques in their manufacture such as extrusion, molding and pre-frying||Poultry and fish “nuggets” and “sticks”
Sausages, hot dogs, luncheon meats, and other reconstituted meat products
|Additives used to make the product palatable or hyper-palatable (flavors, colorants, non-sugar sweeteners and emulsifiers)||Plant-based meat substitutes
Extruded breakfast “cereals”
|Designed to be convenient, palatable alternatives to less processed/freshly prepared dishes and meals||Powdered “instant” soups, noodles and dessert
Infant formulas and “follow-on” milks
“Health” and “slimming” products such as meal-replacement shakes and powder
|Distinguishable from processed foods by the presence of food substances of no culinary use or of additives with cosmetic functions (flavors, flavor enhancers, colors, emulsifiers, emulsifying salts, sweeteners, thickeners and anti-foaming, bulking, carbonating, foaming, gelling and glazing agents) in their list of ingredient||Packaged breads, pastries, cakes, cookies, cake mixes
Sweet or savory snacks; cured meats; ready-to-heat products such as burgers, and pre-prepared pies and pasta and pizza dishes (when made up of food substances of no culinary use and/or contain classes of additives with cosmetic function
|Unprocessed or minimally processed foods are absent or present in small amounts||Alcoholic beverages|
|Adapted from E. Martinez-Steele et al / Nature Food 2023|
Lots of foods are processed to some degree—think canning and bottling or the use of preservatives and antioxidants. But ultraprocessed foods are manipulated far beyond that. Here are the attributes of ultraprocessed foods according to NOVA, a broadly used food classification system developed by researchers at the University of Sao Paulo, Brazil.
Most of the evidence that ultraprocessed foods are harmful comes from observational studies in which participants are asked about the foods they eat and have their health tracked over time. These studies have consistently found that people who ate more ultraprocessed foods were more likely to develop cardiovascular disease, high blood pressure, type 2 diabetes, some types of cancer, obesity, depression, and inflammatory diseases of the gastrointestinal tract such as Crohn’s disease, as well as to die during the course of the studies.