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How Ultra-Processed Foods Affect Your Brain, Heart, Gut and More
Accumulating research shows that eating highly processed foods can put you at risk for several health problems
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Hardly a week goes by without a new headline linking ultra-processed foods to health problems such as dementia, obesity, heart disease and more.
While these studies sound worrisome, it’s difficult for people to know what to do. For many, it’s not even clear what ultra-processed foods are. A new survey published in the American Journal of Public Health found that while nearly 60 percent of adults have heard of ultra-processed foods, only about one-third feel confident in defining them.
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“It’s very hard to know what [ultra-processed food] means,” says Dr. Walter C. Willett, professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health. “Part of the problem with the ultra-processed food category is that some of them are quite healthy. Whole-grain bread can be called an ultra-processed food if it’s made in a factory.” Yet most experts would encourage people to eat more whole grains.
Georgina Burrows, a registered dietitian at UPMC, a medical center in Pittsburgh, says a simple way to identify ultra-processed foods is to look at many of the items in your pantry — salty snacks, bottled dressings, packaged desserts and more.
“Ultra-processed foods usually contain ingredients that you wouldn’t usually see in a home kitchen, so things like stabilizers, flavor enhancers or added sugars, refined starches,” she says. They are foods that have “essentially undergone a high level of industrial processing.”
Most research on ultra-processed foods and health is observational, so it can show links but can’t prove cause and effect. Even so, studies have consistently found associations between diets high in ultra-processed foods and poorer health outcomes.
Here’s what experts across medical specialties say about how these foods may affect different systems in the body.
Ultra-processed foods and the brain
When it comes to the brain, research often examines ultra-processed foods’ ties to the development of dementia or cognitive impairment, depression and stroke — what Dr. W. Taylor Kimberly thinks of as the “big three.”
“We think about brain health as avoiding the types of neurological or brain diseases that are common, that have a big impact on our ability to function day-to-day,” says Kimberly, a professor of neurology at Harvard Medical School.
While there are various reasons people develop these neurological conditions, research shows a diet heavy in ultra-processed foods is linked with an increased likelihood of experiencing one.
“Ultra-processed foods are independently associated with the risk of stroke, the risk of dementia, cognitive impairment … and then also depression,” Kimberly says. “It turns out to be an important and modifiable risk factor for these forms of neurological and neuropsychiatric diseases.”
Research shows that a diet full of ultra-processed foods even speeds up the progression of some neurological conditions.
“It’s associated with an increased rate of cognitive decline,” says Dr. Sarah Song, editor in chief of Brain & Life, which is published by the American Academy of Neurology. “People actually decline faster.”
While experts recognize a connection between eating loads of ultra-processed foods and brain health, they’re not quite sure why yet.
“We’ve got to figure out those details because those details matter and they really inform how anyone wants to individually change,” Kimberly says.
Song says some theories on why ultra-processed foods contribute to depression focus on the brain’s reward system. Eating processed foods feels good but causes “withdrawal when you take them away,” she says. This influences mood.
The good news? When people make “small, incremental changes” to consume fewer ultra-processed foods, they experience bolstered brain health, Kimberly says. Something like swapping water for soda can make a difference.
“You may not feel it right away,” Kimberly says. “You may not even realize it three, four or five years down the road. But studies show that that makes a meaningful impact on your brain health.”
People have to maintain these changes to make a difference. Yet they can do it at any age.
“If you make these changes earlier in life, whether it’s midlife or, gosh, I suppose even earlier than that, that’s going to have a big impact,” Kimberly says. “But so is making a change if you’re 60 or even 70 or 80.”
Ultra-processed foods and the heart
Numerous studies show an association between higher ultra-processed food consumption and a greater chance of cardiovascular disease.
“Things like heart attacks and heart failure and strokes — so those are risks that go up with ultra-processed food consumption,” says Dr. Deepak L. Bhatt, director of Mount Sinai Fuster Heart Hospital in New York City. “We know this from studies that have looked at large populations.”
Bhatt says the association in the research is strong enough that doctors worry about ultra-processed foods’ impact on heart health. Many of the ingredients in ultra-processed foods are known contributors to poorer cardiovascular health.
Ultra-processed foods “have a lot of sodium or salt that drives up blood pressure levels,” Bhatt says. “[Bad fats] in ultra-processed foods can lead to elevations in so-called bad cholesterol, or LDL cholesterol levels. So it’s really a type of diet that’s hitting multiple different pathways that raise cardiovascular risk.”
Even if people have consumed a lot of ultra-processed foods, Bhatt says, it’s never too late to reduce them.
“Once you’re in your 50s, or 60s or 70s, cardiovascular risk goes up quite substantially, risks of things like heart attack and heart failure and stroke,” he says. “Since the risk is higher, the potential benefits are also higher. And studies have shown that even plaque and hardened arteries can reverse with really intense regimens of diet and exercise and lifestyle modification.”
Ultra-processed foods and metabolic and liver health
The definition of ultra-processed foods remains “a moving target,” and Willett says some ultra-processed foods are worse than others.
“The most serious ultra-processed food is not actually a food. It’s sugar-sweetened beverages,” he says. “They have no nutritional value, have huge amounts of sugar, which doesn’t seem to induce satiety when we drink sugar the same way as when consuming sugar in solid form.”
A diet high in sugar-sweetened beverages contributes to various metabolic conditions, such as type 2 diabetes and nonalcoholic fatty liver disease, which is now called metabolic dysfunction-associated steatotic disease, or MASLD.
“It’s no big surprise that we’re having this explosive epidemic of obesity and diabetes,” Willett says. Similarly, the prevalence of MASLD has increased by 50 percent in the past three decades.
There’s another common ingredient in ultra-processed foods that contributes to worsened metabolic health. “Refined grains are also related to diabetes risk, as opposed to whole grains,” Willett adds. Refined grains are grains that have been stripped of many key nutrients, including fiber.
Many ultra-processed foods are lower in fiber and protein, both of which make people feel full, and they’re higher in sugar, refined carbohydrates and sodium.
“It becomes a lot easier for someone to overeat on things such as potato chips, sweets, desserts,” Burrows says. “They can lead to more rapid blood sugar spikes and, over time, insulin resistance.”
Insulin resistance can lead to type 2 diabetes, which affects tens of millions of Americans. More than 28 percent of people over 65 have type 2 diabetes.
Burrows encourages people to add more fresh produce and whole grains to their diets — especially if they cannot eliminate ultra-processed foods.
“I would frame it as an opportunity and not a restriction,” she says. “As we age, the risk of conditions like type 2 diabetes, fatty liver disease and heart disease naturally increases. So that’s when nutrition becomes even more important.”
Cutting out sugary drinks can quickly transform metabolic health. Reducing or eliminating them is “related to less weight gain, less risk of type 2 diabetes,” Willett says. “We can change our metabolism just within a couple of weeks.”
Ultra-processed foods and the gut
Much of the research on ultra-processed foods and gut health examines their associations with colon cancer.
“People should be really cautious about the amounts and the types of ultra-processed foods that they’re consuming,” says Dr. William Chey, president of the American College of Gastroenterology and chief of gastroenterology and hepatology at Michigan Medicine in Ann Arbor. “Ultra-processed foods have been associated, for example, in altering the [gut] microbiome, changing intestinal permeability.”
Having more intestinal permeability, a.k.a. a leaky gut, means that partially digested food and bacteria leave the gastrointestinal system and mingle with the immune system and nerves of the digestive tract.
“That can lead to inflammation,” Chey says. “Anything that leads to chronic inflammation is associated with an increased risk of cancer.”
A leaky gut can also “trigger symptoms” in people with irritable bowel syndrome and inflammatory bowel disease, such as Crohn’s disease and ulcerative colitis.
“That association has definitely been reported,” Chey says. “The causation has not been definitively proven.”
Chey understands that many people can’t easily switch from ultra-processed foods to something like the Mediterranean diet because of cost and availability. Many people across the country live in so-called food deserts, where they lack access to lean proteins, whole grains and fruits and vegetables. Even when healthier options are available, they may not be affordable.
Still, Chey encourages people to choose whole foods as often as possible because they support gut health.
The Mediterranean diet “has now been associated with a reduced risk of IBS, probably a reduced risk of inflammatory bowel disease and probably a reduced risk of colon cancer,” he says. “That’s going to be almost universally recommended.”
Ultra-processed foods and the musculoskeletal system
Recently, researchers have been studying the impact of ultra-processed foods on muscle and bone health and have found that these foods can transform the makeup of both.
In one study, researchers, including Dr. Thomas Link and Dr. Zehra Akkaya, found that people who ate more ultra-processed foods performed worse on physical function tests, including gait speed and repeated chair stands tests. The study also looked at diet and its relationship to the development of knee arthritis in participants over 45 who are at risk of osteoarthritis. The researchers found that ultra-processed foods were linked to worsening knee arthritis, especially in women.
Another study, published this year in the journal Radiology, looked at how ultra-processed foods affect musculoskeletal health (the health of the body’s muscles, bones, joints, tendons, ligaments and connective tissues) in people at risk for knee osteoarthritis.
“We found a significant association between the proportion of [ultra-processed foods] in their diet and fatty infiltration in their tight muscles — independent of total daily calorie or fat intake,” says Akkaya, a coauthor on the study and an associate professor of radiology at Ankara University in Turkey.
Having too much fat in the muscles makes them weaker and may cause more inflammation, says Link, also a coauthor of the study. “The function is reduced, but there’s also a higher risk of injury.”
Fatty muscle also heals more slowly than leaner muscle.
Ultra-processed foods are “not very favorable for musculoskeletal health,” says Link, who is chief of the musculoskeletal imaging section at the University of California, San Francisco. “We have found that not only is the muscle negatively impacted by these foods, but also we found that there was a relationship with symptoms of osteoarthritis.”
This research is still emerging, with more studies needed to understand the connection between ultra-processed foods and muscle health. Link says he is now examining ultra-processed foods and bone health.
“It seems like the early-stage research suggests that there may also be some negative effects on bone,” he says.
Like the other experts, he agrees that making changes at any point can have a positive impact. “If you have these risk factors [for arthritis], then you probably have to take diet more seriously,” he says. “[A] healthy diet is really a key to preventing this.”
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