Ultra Processed Food

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25 Apr 2024

How ultra-processed food harms the body and brain

Consuming ultra-processed foods that are typically high in salt, sugar, and fat—and cheap and accessible—may boost the risk of heart disease, diabetes, anxiety, depression, and cognitive decline.

Although many ultra-processed foods—soda, candy, energy bars, fruit-flavored yogurt, frozen pizza, and frozen meals—can satisfy cravings for sweet, fatty, salty foods, emerging research suggests these items are particularly bad for the heart and brain, with mood and cognition taking a hit.

The most recent meta-analysis looking at the impact of ultra-processed food, published in BMJ in February, found the most far-reaching and unsettling results. Researchers identified direct links between higher consumption of ultra-processed foods and a greater risk of heart disease-related deaths, type 2 diabetes, obesity, wheezing, anxiety, depression, sleep problems, and deaths from all causes.

These results are consistent with earlier studies. Diets high in these foods were linked to a 44 percent greater risk of depression and a 48 percent higher risk of anxiety, according to a meta-analysis published in the journal Nutrients. In one of these studies, risk rose from consuming just 33 percent of calories from ultra-processed food. A separate study from Brazil that tracked 10,775 people found that taking in just 20 percent of calories from these foods was linked to a 28 percent faster rate of cognitive decline compared with people who ate less processed food.

Also alarming is a study tracking about half a million people living in England, Scotland, and Wales that found the risk of dementia went up by 25 percent for every 10 percent increase in ultra-processed food.

“While the exact cause-and-effect relationship is still unknown, the strongest observational evidence from prospective studies leans towards the idea that eating high amounts of ultra-processed foods increases the risk of depression onset in the future,” lead researcher of the Nutrients article, Melissa M. Lane, wrote in an email. She is a post-doctoral research fellow at Deakin University’s School of Medicine, in Geelong, Australia.

It is common knowledge that eating too much salt, sugar, and/or saturated fat is linked to chronic inflammation, high blood pressure, high blood sugar, heart disease, and type 2 diabetes. What the public may not appreciate, however, is that all these conditions affect the brain by raising the risk for vascular dementia—which is decreased blood flow to the brain. Additives such as certain artificial sweeteners and monosodium glutamate may also interfere with the production and release of brain chemicals such as dopamine, norepinephrine, and serotonin, which can adversely affect mental and emotional well-being.

Another problem with ultra-processed foods is that they might be addictive. “Ultra-processed foods have more in common with a cigarette than foods by Mother Nature,” says Ashley Gearhardt, professor of psychology at the University of Michigan, Ann Arbor.

That’s by design; “Multi-billion-dollar companies create these foods to hook us, so our agency around food is low. I see this as a food sovereignty issue,” says Cindy Leung, assistant professor of public health nutrition at Harvard T.H. Chan School of Public Health, Boston.

Humans have evolved to respond to foods that are sweet, fatty, and high in calories. For most of human existence this helped us survive. But in nature, foods are only modestly high in sugar—like berries—or high in fat, like nuts.

“You don’t find foods high in both sugar and fat,” says Gearhardt. “That’s a hallmark of ultra-processed foods. Add in salt, artificial flavorings, and bright colors, and our brain simply loses control over these foods.”

Unprocessed vs. processed vs. ultra-processed

Processed foods can be healthy, it’s the ultra-processed items that are linked to poor health. What’s the difference? Very generally, ultra-processed foods use ingredients not found in a home kitchen. A more precise description comes from the NOVA classification system.

Unprocessed or minimally processed foods such as fresh or frozen fruit, vegetables, seafood, meats, flour, and pasta, usually have just one item on their ingredient lists.

Processed ingredients, such as vegetable oils, sugar, corn starch, are extracted directly from unprocessed foods.

Processed foods, such as bakery bread without preservatives, most cheeses, and tuna, beans or vegetables canned in salt and water have short ingredient lists with recognizable terms, and salt is the main preservative.

Ultra-processed foods include items such as soda, candy, cookies, cake, energy bars, fruit-flavored yogurt, meal replacement bars and shakes, hotdogs, many types of packaged breads and cereals, and frozen meals. They are often high in fat, sugar and/or sodium and typically enhanced with flavorings, dyes, artificial sweeteners and/or other additives. Ingredient lists can be long, like the 48 items in a Nutri-grain Soft Baked Strawberry Breakfast Bar.

How ultra-processed foods mess with your brain

A diet high in ultra-processed foods could hurt your brain for similar reasons that these diets are linked to a slew of other chronic diseases. They’re often high in calories, for example, there’s nearly a day’s worth in the 1,603-calorie Burger King Texas Double Whopper. High calorie diets can lead to obesity, which is linked to depression. One reason why might be that fat cells become dysfunctional and release inflammatory molecules, which are triggers for depression, anxiety, and dementia.

“Ultra-processed foods are effortless to consume in large quantities because they’re generally soft and easy to chew,” Lane explains. They’re also hyper-palatable—that’s the research term for very tasty. “These attributes may disrupt and override the normal 'I’m full' communication between your gut and your brain.”

That’s one explanation for why people spontaneously ate 500 more calories a day, and gained, on average, two pounds during a two-week-long ultra-processed food diet; they lost two pounds on a whole food diet, in a carefully controlled National Institutes of Health experiment.

As these foods are typically hyperpalatable, about 14 to 20 percent of adults and 12 to 15 percent of children and adolescents are food addicted, based on research using the Yale Food Addiction Scale which Gearhardt helped develop. “Those are similar rates of addiction of alcohol and cigarettes,” she says.

By consuming ultra-processed food people neglect the “good stuff” like fruits, vegetables and simply-prepared whole grains.

“That means you’re shortchanged on nutrients that are good for the brain, including phytonutrients—beneficial substances in plants,” Lane wrote. For example, there are about 8,000 varieties of polyphenols that have antioxidant and anti-inflammatory properties; early studies indicate that diets low in these compounds are linked to depression.

Who’s eating them?

U.S. adults take in about 57 percent of calories from ultra-processed foods; children and teens a whopping 67 percent, according to the government’s most recent Health and Nutrition Examination Survey, which is nationally representative. That’s high—levels as low as 20 percent have been linked to ill effects on the brain.

This survey also reveals that Americans of all education and income levels exceed the 50 percent mark for calories from ultra-processed foods. “But people with low food security have an even higher intake,” says Harvard’s Leung, who has done this research.

One reason is that food companies target lower income communities with advertising for soda and other ultra-processed foods. These items are also often the most affordable and accessible, flooding the likes of Dollar Stores and corner markets.

Kicking the habit

Want to reduce the quantity of ultra-processed foods in your diet? Here are some recommendations from our experts that might help.

The first step, says Gearhardt, is to “treat yourself with compassion. It’s not your fault, you’re in an environment designed to addict you.”

Strive to eat three meals and one or two snacks each day. Regular meals prevent you from getting overly-hungry, which leaves you vulnerable to impulse purchases of quick, cheap, ultra-processed food that stimulates the reward centers of the brain.

Switch to less processed foods you still enjoy, such as nuts, and in-season, ripe fruit. “One of my go-to lunches is eggs, a green salad tossed with a delicious dressing and topped with Parmesan cheese, and handful of berries,” says Gearhardt.

Compare labels and choose foods with less sodium and added sugar; and focus on those with a short list of recognizable ingredients.

Some ultra-processed foods are healthier than others, such as supermarket whole wheat bread which offers fiber and other nutrients. “For most people, it’s not practical to go to a bakery to buy bread that doesn’t contain preservatives or other additives,” says Leung.

Leung also suggests that parents make children aware of how the marketing departments of food companies are trying to trick them into buying certain ultra-processed products, and the consequences of eating these items. “Tap into children’s sense of righteous indignation,” she suggests, “by telling them how food companies manipulate them, from the way ultra-processed foods are formulated, to the packaging with cartoon characters, to the placement at eye level and at the check-out aisle.”