The American diet is killing us. On that point, public health experts largely agree.
And in recent years, people who want to make Americans healthier — across the ideological spectrum — are targeting ultra-processed foods, which make up the majority of what Americans eat.
Health Secretary Robert F. Kennedy Jr. has said these foods are "poisoning" Americans and blames them for the chronic disease epidemic. California last month became the first U.S. state to ban certain ultra-processed foods from school lunches. And the Trump administration is working on its own definition of ultra-processed foods to help guide federal policy — and consumers. One recent survey found the majority of U.S. shoppers say they're trying to avoid these foods.
But here's the dilemma: Public health and nutrition experts don't agree on a definition of ultra-processed foods that will actually help make Americans healthier.
'They're not all junk foods'
The term ultra-processed food was developed by Brazilian researchers to describe the level of processing foods undergo. They came up with the NOVA classification system. On one end of the spectrum, there's unprocessed or minimally processed foods — such as an apple or frozen peas.
On the other end, there's ultra-processed foods, which are made from manufactured ingredients and contain additives like artificial colors, flavors, emulsifiers and preservatives. Think processed deli meats, packaged cookies and candies, sweetened beverages and frozen ready meals.
"It's about additives and processing methods that aren't used in home cooking," says Dr. Dariush Mozaffarian, head of the Food is Medicine Institute at Tufts University.
He says nearly 100 observational studies and three different randomized controlled trials have linked overconsumption of ultra-processed foods to a host of health harms — including an increased risk of Type 2 diabetes, obesity, cardiovascular disease, certain cancers and even depression.
But not all foods that fit the definition of ultra-processed are unhealthy, says Julia Wolfson, an associate professor at the Johns Hopkins Bloomberg School of Public Health.
For instance, packaged whole grain breads, plant-based milks and some yogurts are considered ultra-processed, but they can be beneficial for health. One study noted that yogurts were linked to a lower risk of colorectal cancer, even if they had added sugar. Other studies have found ultra-processed whole grain breads are linked to a lower risk of Type 2 diabetes and cardiovascular disease.
And some of these foods can save time and money when cooking at home, such as jarred pasta sauce.
"They're not all junk foods," Wolfson says, so any health policy or regulation shouldn't treat them all the same. "I think it's important to identify foods that are of most concern for health, and not just treat all ultra-processed foods with the same broad brush."
But which foods do you focus on? That's a big point of contention.
Should we target the nutrients?
On one side of the debate you have people like Dr. David Ludwig, a professor of nutrition at the Harvard T.H. Chan School of Public Health and co-director of the New Balance Foundation Obesity Prevention Center Boston Children's Hospital. He thinks the focus should be on the overall nutritional quality of foods, not the processing.
He argues that the concept of ultra-processed foods is too imprecise and can stigmatize healthy food while giving unhealthy food a false health halo. For example, he says, a low-sugar packaged cereal with added protein would be considered ultra-processed, but plain cornflakes are considered minimally processed — even if you pour a bunch of sugar on top at home. He says he'd much rather see kids eating the former breakfast.
The same thing goes with additives. While some additives, such as emulsifiers, have been linked to disruptions in the gut microbiome, others, such as added dietary fiber, are helpful or benign, Ludwig says.
"There are healthful ultra-processed foods and then there are unhealthy ultra-processed foods," Ludwig says. If the category is so diverse, "what's the purpose of the concept in the first place?"
He worries that by targeting this one food category, we could end up with something similar to the 'fat-free' era of the 1980s and '90s. That resulted in a surge of low-fat, high-carb packaged snack foods, which were often loaded with sugar.
Instead of focusing on ultra-processed foods, he says it makes more sense to target nutrients of concern with decades of evidence of harm. Chief among them are highly processed carbohydrates such as added sugars and refined grains like white rice, he says.
The Institute of Food Technologists, which represents food scientists around the globe, has endorsed a similar approach. In comments submitted to the U.S. Food and Drug Administration and the Department of Agriculture, IFT called for a definition that focuses on the nutritional quality of food — such as whether foods are high in salt, sugar and fat — not on the degree of processing.
But can you really ignore the processing?
Any definition that ignores the role of processing is missing the big picture, says Mozaffarian of Tufts University. While ultra-processed foods do tend to be high in salt, sugar and refined starches, "that's not the whole story."
He says,"there's something about the processing itself that's important."
High levels of processing alter the physical and chemical structure of foods in ways that change how our bodies digest them, Mozaffarian says. "We have now molecularly disassembled and reassembled foods in a way that's never been done before in human history."
Think cheese puffs, which are pretty unrecognizable from the corn meal they start with.
"When you lose natural, intact structure, you get very, very rapid digestion of the food in the stomach and small intestine," Mozaffarian says. "So you get bursts of sugar and highly processed starch in your bloodstream."
Over time, these sugar spikes increase the risk of insulin resistance and Type 2 diabetes. Meanwhile, the rapid digestion of food means fewer nutrients reach your lower intestine, where the vast majority of our gut microbes live. So you end up starving your gut microbiome. And that's not good for health because gut microbes break down food that your body can't digest and in turn, they produce chemical messengers that influence everything from your blood sugar levels to your immune system.
And evidence suggests our bodies absorb more calories from ultra-processed foods than they do from high-fiber whole foods.
Mozaffarian says more research is needed to work out the exact mechanisms linking ultra-processed foods to health harms, but he thinks "we know enough to start taking action."
So what's a consumer to do?
For now, there's no avoiding the fact that the majority of the foods sold in grocery stores are ultra-processed, says Wolfson of Johns Hopkins. And for many people, these foods are often the more affordable and accessible option. If the Trump administration truly wants to help Americans become healthier again, Wolfson says it also needs to adopt policies that help people afford healthier options.
In the meantime, she says there are ways to make smarter choices within the ultra-processed category. For example, when shopping for packaged breads, look for whole grain options. And try to reduce consumption of sugar and artificially sweetened beverages and processed meats, two food categories that are most strongly linked to health harms.
And she says, get in the habit of reading ingredient lists. If it's really long and full of emulsifiers, dyes, and colorings, try to find an alternative product "with the fewest of those ingredients that you don't know and can't pronounce."
You might not always find an option that's not ultra-processed but you can "try to maximize the nutrition and minimize the processed ingredients," she says. "It's a tradeoff."
Eat as many whole foods as you can. Beans, frozen fruits and vegetables are often more affordable options.
Ultimately, though, "If all the experts are disagreeing right now about exactly what to do, imagine what it's like for the average consumer?" Mozaffarian says. That's why he wants to see federal policy to provide guidance.
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