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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 cereals at breakfast to frozen pizzas at dinner, plus in-between snacks of potato chips, sodas and ice cream, ultra-processed foods make up about 60% of the U.S. diet. For kids and teens, it’s even higher (about two-thirds of what they eat). 

That’s concerning because ultra-processed foods have been linked to a host of negative health effects — from obesity and diabetes to heart disease, depression, dementia and more. One recent study suggested that eating these foods may raise the risk of early death. 

Nutrition science is tricky, though, and most research so far has found connections, not proof, regarding the health consequences of these foods. 

Food manufacturers argue that processing boosts food safety and supplies, and offers a cheap, 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 account for what one study estimates is 73% of the U.S. food supply. 

The Associated Press asked several nutrition experts, and here’s what they said. 

What are ultra-processed foods? 

Most foods are processed, whether it’s by freezing, grinding, fermentation, pasteurization or other means.  

In 2009, Brazilian epidemiologist Carlos Monteiro and colleagues first proposed a system that classifies foods according to the amount of processing they undergo — not by nutrient content. 

At the top of the four-tier scale are foods created through industrial processes and with ingredients such as additives, colors and preservatives that you couldn’t duplicate in a home kitchen, said Kevin Hall, a researcher who focuses on metabolism and diet at the National Institutes of Health. 

“These are most, but not all, of the packaged foods you see,” Hall said. 

Such foods are often made to be both cheap and irresistibly delicious, said Dr. Neena Prasad, director of the 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 doesn’t determine whether a food is unhealthy or not, Hall noted. Whole-grain bread, yogurt, tofu and infant formula are all highly processed, for instance, but they’re also nutritious.  

Here’s the tricky part: Many studies suggest that diets high in such foods are linked to negative health outcomes.  

But these kinds of studies can’t say whether the foods are the cause of the negative effects — or whether there’s something else about the people who eat these foods that might be responsible. 

At the same time, ultra-processed foods, as a group, tend to have higher amounts of sodium, saturated fat and sugar, and tend to be lower in fiber and protein. It’s not clear whether it’s just these nutrients that are driving the effects. 

A small, interesting study 

Hall and his colleagues were the first to conduct a small but influential experiment that directly compared the results of eating similar diets made of ultra-processed versus unprocessed foods. 

Published in 2019, the research included 20 adults who went to live at an NIH center for a month. They received diets of ultra-processed and unprocessed foods matched for calories, sugar, fat, fiber and macronutrients for two weeks each, and were told to eat as much as they liked. 

When participants ate the diet of ultra-processed foods, they consumed about 500 calories per day more than when they ate unprocessed foods, researchers found — and they gained an average of about two pounds during the study period.  

When they ate only unprocessed foods for the same amount of time, they lost about two pounds. 

Hall is conducting a more detailed study now, but results aren’t expected until late next year. He and others argue that such definitive research is needed to determine exactly how ultra-processed foods affect consumption. 

“It’s better to understand the mechanisms by which they drive the deleterious health consequences, if they’re driving them,” he said. 

What it means for you 

So, how should consumers manage ultra-processed foods at home? 

In countries like the U.S., it’s hard to avoid highly processed foods — and not clear which ones should be targeted, said Aviva Musicus, science director for the Center for Science in the Public Interest, which advocates for food policies. “The range of ultra-processed foods is just so wide,” she said. 

Instead, it’s better to be mindful of the ingredients in foods. Check the labels and make choices that align with the current U.S. Dietary Guidelines, she suggested. 

“We have really good evidence that added sugar is not great for us. We have evidence that high-sodium foods are not great for us,” she said. “We have great evidence that fruits and vegetables which are minimally processed are really good for us.” 

It’s important not to vilify certain foods, she added. Many consumers don’t have the time or money to cook most meals from scratch. 

“Foods should be joyous and delicious, and shouldn’t involve moral judgment,” Musicus said. —AP