Whether they know it or not, most Americans don’t go a day—or often a single meal—without eating ultra-processed foods.
From sugary breakfast cereals to frozen pizzas for dinner, to chips, soda and ice cream, ultra-processed foods make up about 60% of the American diet. For children and teens, it’s even higher: about two-thirds of what they eat.
This is concerning because ultra-processed foods are linked to a number of negative health effects, from obesity and diabetes to heart disease, depression, dementia and more. A recent study suggests that eating these foods may increase the risk of premature death.
The science of nutrition, however, is complex, and most of the research to date has established links, not evidence, about the health consequences of these foods.
Food manufacturers say processing improves food safety and supply and provides an inexpensive, convenient way to provide a diverse and nutritious diet.
Even if the science were clear, it’s hard to know what practical advice to give when ultra-processed foods make up, according to one study, 73% of the U.S. food supply.
The Associated Press asked several nutrition experts and here’s what they had to say:
What are ultra-processed foods?
Most foods are processed, whether through freezing, grinding, fermentation, pasteurization, or other means. In 2009, Brazilian epidemiologist Carlos Monteiro and his colleagues were the first to propose a system that classifies foods based on the degree of processing they undergo, rather than their nutrient content.
At the top of the four-tiered scale are foods created through industrial processes and with ingredients such as additives, colorings and preservatives that you couldn’t reproduce in a home kitchen, said Kevin Hall, a researcher who focuses on metabolism and nutrition at the National Institutes of Health.
“These are most, but not all, of the packaged foods you see,” Hall said.
These foods are often marketed as both cheap and irresistibly delicious, said Dr. Neena Prasad, director of Bloomberg Philanthropies’ food policy program.
“They have just the right combination of sugar, salt and fat and you just can’t stop eating them,” Prasad said.
However, the level of processing alone does not determine whether a food is unhealthy or not, Hall stressed. Whole-grain bread, yogurt, tofu and baby formula are all highly processed, for example, but they are also nutritious.
Are ultra-processed foods harmful?
Here’s the problem. Many studies suggest that diets high in these foods are linked to negative health effects. But these studies can’t say whether these foods are the cause of the negative effects, or whether something else about the people who eat them might be responsible.
At the same time, ultra-processed foods, as a group, tend to contain higher amounts of sodium, saturated fat, and sugar, and tend to be lower in fiber and protein. It’s unclear whether these nutrients are solely responsible for these effects.
Hall and his colleagues were the first to conduct a small but influential experiment that directly compared the outcomes of similar diets consisting of ultra-processed foods and unprocessed foods.
Published in 2019, the study involved 20 adults who lived at an NIH center for a month. They ate a diet of ultra-processed and unprocessed foods with identical calorie, sugar, fat, fiber, and macronutrient intakes for two weeks each, and were told to eat as much as they wanted.
The researchers found that participants who ate a diet based on ultra-processed foods ate about 500 more calories per day than those who ate unprocessed foods. They also gained an average of about 2 pounds during the study period. When they ate only unprocessed foods for the same period, they lost about 2 pounds.
Hall is currently conducting a more detailed study, but the process is slow and expensive, and results aren’t expected until late next year. Such definitive research is needed to determine exactly how ultra-processed foods affect consumption, he and other researchers say.
“It is better to understand the mechanisms by which they cause adverse health consequences, if they do,” he said.
Should ultra-processed foods be regulated?
Some ultra-processed food advocates, like Prasad, say the many studies linking ultra-processed foods to health problems should be more than enough to prompt government and industry policy changes. She calls for measures like raising taxes on sugary drinks, tightening restrictions on manufacturers’ sodium content, and cracking down on marketing these foods to children, much as tobacco marketing is restricted.
“Do we want to risk our kids getting sicker while we wait for this perfect evidence to come out?” Prasad asked. Earlier this year, FDA Commissioner Robert Califf addressed the issue, telling a conference of food policy experts that ultra-processed foods are “one of the most complex things I’ve ever dealt with.”
But, he concluded, “we have to have a scientific basis and then we have to implement it.”
How should consumers handle ultra-processed foods at home?
In countries like the United States, it’s hard to avoid highly processed foods — and it’s not clear which ones to target, said Aviva Musicus, science director at the Center for Science in the Public Interest, which advocates for food policy.
“The range of ultra-processed foods is so broad,” she said.
It’s best to be mindful of food ingredients. Check labels and make choices that are consistent with current U.S. dietary guidelines, she suggested.
“We have strong evidence that added sugar is not good for us. We have evidence that high-sodium foods are not good for us,” she said. “We have strong evidence that minimally processed fruits and vegetables are really good for us.”
It’s important not to denigrate certain foods, she added. Many consumers don’t have the time or money to cook most of their meals themselves.
“I think food should be joyful and delicious and should not involve moral judgment,” Musicus said.
