(CNN) — Eating a greater amount of ultraprocessed food was associated with a higher risk of developing cancers of the upper digestive tract, such as mouth, throat and esophageal cancer, according to a new study. In the United States, a 2019 study estimated some 71% of the food supply may be ultraprocessed.
People who consumed 10% more ultraprocessed foods than others in the study had a 23% higher risk of head and neck cancer and a 24% higher risk of esophageal adenocarcinoma, a type of cancer that grows in the glands that line the insides of organs, researchers found.
“This study adds to a growing pool of evidence suggesting a link between UPFs (ultraprocessed foods) and cancer risk,” said Dr. Helen Croker, assistant director of research and policy at World Cancer Research Fund International, which funded the study, in a statement.
Much more research and data collection are needed to understand the link the new report found, said study coauthor Dr. Ingre Huybrechts, a nutritional epidemiologist in the Nutrition and Metabolism Branch at the International Agency for Research on Cancer, which helped sponsor the study.
The dietary data was collected in the 1990s, “when the consumption of UPFs was still relatively low,” Huybrechts said. “As such, associations may potentially be stronger in cohorts including recent dietary follow-up assessments.”
Ultraprocessed foods — such as sodas, chips, nuggets, packaged soups, ice cream and more — contain ingredients “never or rarely used in kitchens, or classes of additives whose function is to make the final product palatable or more appealing,” according to the Food and Agriculture Organization of the United Nations.
The list of additives includes preservatives to resist mold and bacteria; emulsifiers to keep incompatible ingredients from separating; artificial colorings and dyes; anti-foaming, bulking, bleaching, gelling and glazing agents; and added or altered sugar, salt and fats designed to make food more appealing.
Body fat as a risk factor
The new study, published Tuesday in the European Journal of Nutrition, analyzed diet and lifestyle data, including questions on ultraprocessed food consumption, on 450,111 adults who were participating in the European Prospective Investigation into Cancer and Nutrition, or EPIC. One of the largest such studies in Europe, EPIC recruited participants between 1992 and 1999 from 23 centers across 10 European countries and the United Kingdom.
Being overweight or obese is a well-known risk factor for developing at least 13 types of cancer, including cancer of the esophagus, according to the US Centers for Disease Control and Prevention. Ultraprocessed foods are often calorie-dense and are considered to be a driver of excess weight, experts say.
After performing statistical analysis on the results, however, researchers found increases in body fat accounted for only some of the statistical association between ultraprocessed food and cancers of the upper digestive tract over a 14-year period.
An increased waist-to-hip ratio only explained 5% of the 23% higher risk for head and neck cancer, according to the study. An increase of body mass index, or BMI, explained 13% of the 24% additional risk for esophageal cancer, while waist-to-hip ratio explained 15%.
“In other words, if UPFs contribute to cancer risk, they do it to a small extent by contributing to obesity, and to a much larger extent by other mechanisms,” said Dr. David Katz, a specialist in preventive and lifestyle medicine who was not involved in the study.
“What might those be? Diet-induced inflammation; disruption of the microbiome; adverse epigenetic effects; and many other possibilities come to mind,” said Katz in an email. Katz founded the nonprofit True Health Initiative, a global coalition of experts dedicated to evidence-based lifestyle medicine.
It’s possible that ingredients such as emulsifiers, preservatives, artificial sweeteners and toxins found in food packaging might also play a role in the link between ultraprocessed food and cancer or other diseases, the study authors said.
An unusual link
Oddly, the study also found a link between ultraprocessed food and accidental deaths, which was being used as a control for the study.
“The researchers used accidental death as a ‘negative control,’ i.e. something with which UPFs should not be associated if only direct impacts were being tallied,” Katz said in an email.
“UPFs were, however, associated with a higher rate of accidental death — suggesting that UPFs are a marker for adverse circumstances in general. Among the factors that might contribute to this association are poverty, discrimination, environmental blight and so on.”
Therefore, it’s not clear just what is behind the link, said study coauthor Dr. George Davey Smith, a professor of clinical epidemiology at the University of Bristol in the UK.
“UPFs are clearly associated with many adverse health outcomes, yet whether they actually cause these, or whether underlying factors such as general health-related behaviours and socioeconomic position are responsible for the link, is still unclear,” he said in a statement.
A growing association
This is not the first study to find a link between ultraprocessed food and cancer. An August 2022 study found eating ultraprocessed foods significantly increased men’s risk of colorectal cancer as well as a higher risk of heart disease and early death in both men and women.
A study published in January found each 10% increase in ultraprocessed food consumption was associated with a 2% increase in developing any cancer — and a 19% increased risk for being diagnosed with ovarian cancer.
Another recently published study using EPIC data found eating higher amounts of ultraprocessed food raised the risk of being diagnosed with multimorbidity, which is having multiple chronic conditions such as diabetes, heart disease and cancer. In that study, eating more ultraprocessed animal products and sweetened beverages explained a good part of the association.
Another 2023 study found eating greater amounts of ultraprocessed food and drinks, especially if those items are artificially sweetened, could be linked to the development of depression in women. Eating 400 calories a day of ultraprocessed food as part of a 2,000-calorie diet increased the risk for dementia, according to a 2022 study.
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