‘The health challenge of our time’: What academic experts want you to know about ultra-processed foods

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In July 2025, the U.S. Food and Drug Administration (FDA) and the Department of Agriculture (USDA) attempted to define one possible culprit for the nation's poor health: ultra-processed foods (UPFs). While concerns have been growing for decades about the link between chronic disease and a poor diet, it is only in the past few years that researchers have singled out highly processed foods as being uniquely and specifically harmful.

But clarity is needed to guide federal policy, regulate the food industry, and help Americans make healthy food choices. One survey found that 74% of U.S. adults believe UPFs are bad for their health, but most have trouble identifying them.

The term "ultra-processed foods" was coined in 2009 by Carlos Monteiro, PhD, a nutrition epidemiologist at the University of São Paulo, in Brazil, as part of a food-classification system known as NOVA, which categorizes foods by the degree of processing they undergo: (1) unprocessed or minimally processed; (2) processed culinary ingredients such as vegetable oils, butter, sugar, and vinegar; (3) processed foods, including canned vegetables and fish, cheese, and unpackaged fresh breads; and (4) ultra-processed foods, or UPFs.

Examples of UPFs include soft drinks, packaged snacks, candy, ice cream, salad dressings, jarred sauces, sweetened cereals, packaged breads, pastries, cookies, fast foods, processed meats, and many other ready-to-eat or ready-to-heat products.

"These are industrially manufactured foods that often contain ingredients not typically used in home cooking, such as additives, emulsifiers, flavor enhancers, colors, and other compounds designed to improve taste, texture, shelf life, and convenience," says Michael Shapiro, DO, the Fred M. Parrish professor of cardiology and molecular medicine at Wake Forest University School of Medicine, in Winston-Salem, North Carolina. Shapiro has studied the effects of UPFs, most recently on cardiovascular health.

Research shows UPFs account for 57% of the calories adults in the United States consume and 67% of the calories in children's diets. And a growing body of data links heavy consumption of UPFs to dozens of adverse health outcomes. A 2024 umbrella-review study found a strong correlation between UPFs and no fewer than 32 different "health parameters spanning mortality, cancer, and mental, respiratory, cardiovascular, gastrointestinal, and metabolic health outcomes," the authors wrote.

"This is the health challenge of our time," says Dariush Mozaffarian, MD, DrPH, director of the Food is Medicine Institute at Tufts University, in Boston, and distinguished professor, dean emeritus, and Jean Mayer professor at the Friedman School of Nutrition Science and Policy at Tufts.

The link between UPFs and poor health

Since NOVA was introduced, hundreds of studies have detailed health harms due to UPFs. In the past year alone, UPFs have been linked to arthritis, precancerous colon polyps in women younger than 50, prediabetes in young adults, reduced fertility, cognitive decline, and a higher risk for developing multiple sclerosis.

A recent study implicating UPFs for poor bone health is typical.

"High intake of UPFs was related to a reduction of bone mineral density at multiple sites, including the femoral neck, femur trochanter, lumbar spine, and total body," says study author Lu Qi, MD, PhD, chair and professor at the Tulane University Weatherhead School of Public Health and Tropical Medicine, in New Orleans, and director of Tulane's Obesity Research Center and its Personalized Health Institute.

Researchers have demonstrated a particularly strong link between UPFs and cardiovascular health, with significant repercussions for people.

"Fourteen out of 15 adults have suboptimal cardio metabolic health if you look at just four risk factors: blood pressure, blood glucose, blood cholesterol, and body weight," says Mozaffarian. "And that's not even counting mental health, gut health, immunity, brain health - all the other things that we know that diet affects."

Giulia Menichetti, PhD, a principal investigator and assistant professor of medicine at Brigham and Women's Hospital and Harvard Medical School, shares the concern. "Nutrition is among the strongest drivers of human health," she says. Menichetti studies UPFs and heads the Foodome Project, an initiative aimed at deciphering the chemical complexity of food, to better understand what we eat. Her lab has determined that 73% of the U.S. food supply is composed of UPFs.

How UPFs harm health

In fact there are several mechanisms by which UPFs harm health. Processing strips helpful nutrients from whole foods, while adding new components that can pose a threat, experts say. Packaging itself can expose foods - and people - to dangerous substances.

To start, UPFs typically contain unhealthy fats, sugar, and salt in levels associated with obesity and poor overall health.

"Lots of studies show that UPFs have worse nutritional profiles [than unprocessed foods]," says Mozaffarian. "The two biggest problems are with refined starch and salt, followed by added sugars."

The processing itself also appears to play a critical role in the connection between these foods and disease. One problem is the loss of nutrients intrinsic to the process.

"Beyond what we measure, like fiber and traditional vitamins, there are thousands of trace compounds - like cocoa flavonoids or phytonutrients in blueberries - in whole foods," says Mozaffarian. "It's very likely that industrial and commercial processing destroys those, and so we're losing the natural diversity of nutrients in foods." That could contribute to chronic diseases such as heart disease, diabetes, and cancer.

Moreover, by taking apart and then recombining food molecules, processing destroys the natural cellular structure of foods, with potentially hazardous consequences.

"The molecular disassembly of UPFs dramatically changes where and how quickly food is digested. You have more rapid digestion, which leads to a higher glycemic index," Mozaffarian explains. "And by doing that, you're not getting calories to the large intestine and to gut bacteria there, so they're not able to supply the normal wealth of beneficial metabolites they normally produce."

The presence of a myriad of food additives also concerns experts. "There's increasing evidence for potential harms from artificial sweeteners, artificial preservatives, colors and dyes, and even emulsifiers and stabilizers - things we thought were innocuous," Mozaffarian says. "But there's more and more evidence that these things are not inert and might have harms."

In addition, by combining nutrients, such as sugar and salt, in ways that aren't found in nature, UPFs are engineered to be highly palatable, which can lead to overeating.

"The sensory characteristics that are basically driven by these exotic combinations are believed to override satiety signals, promoting excess intake," says Menichetti. And that can displace healthier foods from the diet.

Dangers may even lurk in food packaging, from contaminants to microplastics and chemicals, including bisphenols and phthalates, Mozaffarian adds.

Not all processed foods are bad

Still, some amount of processing is OK in the scheme of things, experts say. Instant oatmeal and packaged yogurt, for instance, can be good choices.

"Not all UPFs are the same in terms of their links with adverse health outcomes," says Casey Rebholz, PhD, MPH, an associate professor of cardiovascular and clinical epidemiology at the Bloomberg School of Public Health at Johns Hopkins University, in Baltimore. Rebholz has studied UPFs extensively. "Some of the most consistent findings we've seen are that meats and sugar-sweetened beverages that are ultra-processed are adversely associated with health outcomes. Other types of UPFs, including yogurt and cereals, are less consistently associated with adverse outcomes."

Scientists are trying to figure out the differences. But they're finding that the most processed foods contain "nutritional dark matter," the term Menichetti uses to describe the thousands of unknown chemical compounds found in foods.

Menichetti's lab is involved in ranking UPFs by their potential harms and is also in the process of mapping the compounds present in all foods.

Food is usually described through the number of calories, and the presence of macronutrients, vitamins, and minerals, Menichetti explains. USDA databases focus on a relatively small number of nutrients, about 150.

However, "our work has shown that food contains a much larger molecular universe," Menichetti says.

Using network science, which relies on computational modeling to map complex relationships between ingredients, chemical compounds, and health outcomes, Menichetti's Foodome Project has identified more than 140,000 distinct food molecules - molecules that don't just fuel the body but regulate the gut microbiome and a variety of other cellular processes. The project aims to map nutritional dark matter in a way similar to what the Human Genome Project did for the human body.

Governments are stepping in

Cataloging nutrients is one step toward the goal of improving America's nutritional status. But changes in the food industry may be necessary to make a significant difference in the nation's health, Mozaffarian says. Currently, unlike in many other countries, U.S. food manufacturers can use a regulatory loophole to alter foods in hidden and potentially questionable ways.

"One of the questions I'm frequently asked by patients or members of the public is, how have Europe, Australia, and New Zealand banned all these additives and the U.S. hasn't?" Mozaffarian says. "And the answer is the GRAS [generally regarded as safe] loophole."

GRAS refers to a category of ingredients that can be added to processed foods and was originally intended for common substances such as turmeric or ginger.

"But under the loophole, food companies can decide for themselves if ingredients are safe or unsafe, notification [to the FDA] is voluntary, and they don't need to make safety testing public," says Mozaffarian. "Basically 99% of compounds have entered the food supply in the U.S. under the GRAS pathway, which means that the FDA doesn't even know they're there. And the assumption is something is safe until harm is proven. It puts the burden of proof on public health rather than on industry."

The U.S. Department of Health and Human Services (HHS) is taking steps to close the GRAS loophole, however. Last year HHS Secretary Robert F. Kennedy Jr. directed the FDA to explore new rules to eliminate the pathway, and they are under review with the administration, Mozaffarian says.

"When the vast majority of Americans are sick with diet-related disease, we can no longer rest on the presumption of safety," he says. "We have to reverse the process."

At the same time, at least 30 states are passing bills to define and address ultra-processed foods. A California bill establishes a definition for UPFs and calls for some to be removed from school meal programs by 2035. And San Francisco has filed a lawsuit against 12 major food manufacturers, alleging that the UPFs they produce are addictive and fuel chronic diseases such as heart disease and cancer.

Meanwhile, the FDA and the USDA have gathered public information and continue to work to develop a consistent definition of UPFs for the public and policymakers.

Doctors help patients navigate the complexities

Even without federal or state intervention, though, physicians have been working to educate their patients.

"Ultra-processed foods are inexpensive, convenient, heavily marketed, widely available, and often engineered to be highly appealing," says Shapiro. "For many people, especially those with limited time, limited income, or limited access to healthier foods, simply saying 'Eat less processed food' is not very helpful."

He suggests starting with substitutions: Replace sugary cereals with oatmeal or higher-fiber options, and packaged snacks with nuts, fruit, yogurt, or simple whole-food snacks. Cook more meals at home when feasible, and choose foods with shorter ingredient lists. Veer toward minimally processed foods "rather than trying to be perfect," Shapiro adds.

Rebholz concurs. Data suggest that the more UPFs you eat, the higher your health risks, but "any reduction could result in potentially substantial improvements in cardiometabolic health," she says. She recommends shopping the perimeter of the grocery store, where the produce, protein, and dairy products are typically placed, and studying food labels on packaged items, which dominate the store's middle aisles.

Acknowledging the ubiquity of UPFs, Shapiro also offers advice to his fellow clinicians and physician-scientists:

"We need to avoid framing this as purely an issue of personal responsibility," he says. "Many dietary choices are shaped by cost, access, time, marketing, and the surrounding food environment."