Study: Ultra-processed foods boost cancer risk

A new study shows that eating ultra-processed foods can increase cancer risk and other diseases. Here’s what you can do to reduce those risks.
March 10, 2023
A woman reads the label on a bag of potato chips while standing in the snack food aisle at a grocery store.
A new study shows that eating processed foods can raise cancer risk. Ultra-processed foods have also been implicated in increased risk for diabetes, dementia and cardiovascular disease. Photo: Getty Images.

Ultra-processed foods again made the news recently, and again for all the wrong reasons. This time, a British study involving nearly 200,000 UK Biobank participants found that every 10% increment in the ultra-processed food content of one’s diet increased the average risk of 34 types of cancer by 2% – and that of ovarian cancer by 19%.

In a country awash in ultra-processed foods (they comprise close to 60% of our total calories), that’s bad news indeed.

Dr. Marisa Moroney, a University of Colorado School of Medicine and UCHealth gynecologic oncologist, said that while the ovarian cancer data were notable, the key takeaway was its reminder of the bigger picture of ultra-processed foods’ impact on well-being.

“It adds to the growing evidence that ultra-processed foods negatively impact our health, and one of the ways that seems to be is through increasing the risk of cancer,” Moroney said.

Ultra-processed foods – classic junk foods and sugary sodas, as well as many breakfast cereals, packaged baked goods, ready-to-eat meals, snack bars, and sweetened yogurts– have a long rap sheet indeed. They’ve been implicated in diabetes, dementia, cardiovascular disease, and other health problems. While there are no hard and fast definitions, ultra-processed foods have long ingredient lists and, often, a ton of fat, sugar, sodium, and artificial flavors crafted by savvy food engineers to enrapture the human tongue.

The rest of the body seems less enamored. The study’s design made it impossible to determine what might be causing cancer upticks, but it’s something besides sociodemographic characteristics, smoking status, physical activity, body mass index, and alcohol and calorie intake – all of which the researchers statistically adjusted for.

What is the link between eating ultra-processed foods and cancer?

What, then, might it be? The authors provided a few possibilities: food additives, contaminants such as acrylamide created chemically during ultra-processing, artificial sweeteners, nitrates, and endocrine-disrupting phthalates and bisphenols leached in from plastic packaging.

Dr. Marisa Moroney, University of Colorado School of Medicine and UCHealth gynecologic oncologist, discusses the new study regarding the link between ultra-processed foods and cancer.
Dr. Marisa Moroney

But nobody really knows, and the British study was observational – patients self-reported their diets between 2009 and 2012, and researchers cross-referenced patients with cancer-registry data through about 2015 in Scotland and 2019 in England and Wales. Such studies don’t establish cause and effect.

“Because this is an observational study, we just don’t know what it is about these foods that our body reacts to in a different way that causes the increased risk of cancer,” Moroney said.

Moroney, who specializes in treating ovarian cancer, was surprised by the study’s eyebrow-raising ovarian cancer finding. She says that she’d like to see follow-on studies that support the apparently extreme link between ultra-processed foods and ovarian cancer. The main risk factors for ovarian cancer, she says, are genetics (such as the BRCA gene) and how many years a woman has been ovulating.

“It may be an inflammatory process, and we think inflammation can lead to certain cancers,” Moroney said.

Watch the sugar, fat

Better understood are two linked factors proven to elevate cancer risk: one between ultra-processed foods and weight gain, and a second between excess body weight and cancer incidence.

“There’s a lot of evidence that being overweight or obese as an adult puts someone at risk for a lot of different cancers,” said Amy Weiman, the clinical nutritional supervisor for Oncology at the UCHealth Cancer Care – Anschutz Medical Campus. “Just having extra body fat increases inflammation throughout the body and being in a state of chronic inflammation puts people at risk for cancer-cell growth.”

Being overweight or obese also boosts growth-hormone production that can stimulate cancer growth, Weiman added.

Sugar and corn syrup, abundant in many ultra-processed foods, stoke inflammation, Weiman says. Overeating carbohydrates – be it sugar consumed directly or broken down from simple starches – kicks off insulin production and a chain reaction that turns excess carbs into fat, and that process is also inflammatory, she says. That’s bad for you regardless of body weight, she adds.

Amy Weiman, the clinical nutritional supervisor for Oncology at the UCHealth Cancer Care – Anschutz Medical Campus, discusses the new study regarding the link between ultra-processed foods and cancer.
Amy Weiman

Despite all that, Weiman doesn’t tell patients or those looking to improve their diets to give up ultra-processed foods completely – though she does recommend skipping sugary soda, a font of empty calories with no nutritional value.

“But everything else, I try to put in a realistic and attainable way. If you like pizza, have pizza once a month so it doesn’t make you crazy,” she said. “I have a sweet tooth, so I might skip the starch, have a dinner of lean meat, roasted veggies, and a salad, and then have a piece of banana bread that I made.”

Steps to cut back on ultra-processed foods

The biggest step one can take in cutting back on ultra-processed foods, Weiman says, is boosting intake of whole foods and plants – fresh fruit, vegetables, whole grains, beans, nuts, and healthy carbohydrates and starches such as sweet potatoes, and squash. Plants also provide antioxidants and phytonutrients that may help prevent chronic diseases including cancer. Also, their fiber makes them slower to digest than ultra-processed foods, which keeps you sated longer.

For proteins, she points to eggs and unprocessed meats (though red meat is linked with colon cancer and is best limited to three times a week, she says) including rotisserie chicken, which, while seasoned, are not highly processed. Canned tuna, lowfat Greek yogurt, and milk are also good protein options, though plant-based milk has less protein than cow milk.

Part of the game is having more control over what you eat. A baked russet potato is better than potato chips or macaroni and cheese, Weiman says – plus you can limit what you put on it.

“Everything in moderation,” she said. “I never tell people, ‘Don’t eat the foods you crave.’ Just try to eat them less, so you eat the healthy foods more.”

The new British study asks as many questions as it clears up, but it further bolsters the case for avoiding ultra-processed foods. Given how addictive, convenient, and, for industrial food makers, profitable these products are, it’s going to take increased awareness and a heaping portion of willpower to do so.

About the author

Todd Neff has written hundreds of stories for University of Colorado Hospital and UCHealth. He covered science and the environment for the Daily Camera in Boulder, Colorado, and has taught narrative nonfiction at the University of Colorado, where he was a Ted Scripps Fellowship recipient in Environmental Journalism. He is author of “A Beard Cut Short,” a biography of a remarkable professor; “The Laser That’s Changing the World,” a history of lidar; and “From Jars to the Stars,” a history of Ball Aerospace.