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MONDAY, Nov. 17, 2025 (HealthDay News) — Younger adults who eat lots of ultra-processed foods are more likely to develop polyps that can become , a new study says.

Women under 50 whose diets contained the largest amounts of ultra-processed foods had a 45% higher risk of developing pre-cancerous polyps in their colon, researchers reported Nov. 13 in .

“Our findings support the importance of reducing the intake of ultra-processed foods as a strategy to mitigate the rising burden of early-onset colorectal cancer,� said senior researcher , chief of the Clinical and Translational Epidemiology Unit at the Mass General Brigham Cancer Institute in Boston.

“The increased risk seems to be fairly linear, meaning that the more ultra-processed foods you eat, the more potential that it could lead to colon polyps,� he added in a news release.

The findings might partially explain a rapid increase in colon cancer cases among younger adults.

Diagnoses of advanced-stage colon cancer among people under 55 doubled from 11% in 1995 to 20% in 2019, according to a 2023 American Cancer society .

Ultra-processed foods are made mostly from substances extracted from whole foods, like saturated fats, starches and added sugars. They also contain a wide variety of additives to make them more tasty, attractive and shelf-stable.

Examples include packaged baked goods, sugary cereals, ready-to-eat or ready-to-heat products and deli cold cuts.

“These foods have low nutritional value and often include unhealthy additives such as artificial flavorings, stabilizers, emulsifiers, gums and synthetic food coloring,� said , an associate professor and cancer epidemiologist at the Northwell Health Cancer Institute in Great Neck, N.Y., who was not involved in the study.

“Ultimately, they are extensively processed to the point where they are devoid of their inherent nutrient value,� she added in a news release. “Food manufacturing in the U.S. has dramatically changed over the last century where we barely recognize the food or the ingredients in the foods that we are eating.�

For the new study, researchers analyzed 24 years of data from a long-term health study of female nurses born between 1947 and 1964.

Their analysis included more than 29,000 nurses who received at least two lower endoscopies before they turned 50 to screen for early signs of colon cancer.

Nearly 2,800 of the women had developed pre-cancerous polyps that were found during their colon cancer screening, researchers found.

The participants also completed diet surveys every four years, from which researchers estimated their average intake of ultra-processed foods.

On average, the nurses ate 5.7 servings of ultra-processed foods per day, amounting to 35% of their total daily calories, researchers said. That’s slightly lower than the U.S. national average.

Women who ate the most ultra-processed foods – 10 servings per day on average – had a 45% higher risk of developing pre-cancerous polyps in their colon, compared to women who ate three servings a day on average.

“One of the strengths of our study was that we had detailed information about other colorectal cancer risk factors in the participants, such as such as body mass index, type 2 diabetes and low fiber intake,� Chan said. “Even after accounting for all these other risk factors, the association with ultra-processed foods still held up.�

Even though the study featured women, Molmenti said its findings likely apply to men as well.

“This is a message for the entire population,� Molmenti said. “If you did the same study and replicated it in a large cohort study among men, you might find the same result. This does not show any disparity between men and women in terms of risk factors.�

Researchers are now working on ways to better categorize ultra-processed foods, since some might be more harmful than others.

They’re also trying to identify other risk factors for early-onset colon cancer.

“Diet isn't a complete explanation for why we're seeing this trend — we see many individuals in our clinic with early-onset colon cancer who eat very healthy diets,� researcher Chan said.

Meanwhile, Molmenti noted that there are many ways that ultra-processed foods might increase colon cancer risk.

“Everything that we eat touches our colon; good or bad,� she said. 

Junk foods and ultra-processed foods can disrupt the microbiome, Molmenti said, and can also lead to inflammation. In addition, they can lead to insulin resistance and metabolic dysregulation so that the body and colon are not in sync.

"And, they're just not in a format that they can prevent disease,� she said

“Ultra-processed foods and junk foods promote disease, and that is why this study, I think, is showing that there is this increased risk among young women under 50 who are consuming large amounts of these foods,� Molmenti said.

More information

Yale School of Public Health has more on .

SOURCES: Mass General Brigham, news release, Nov. 13, 2025; Northwell Health, news release, Nov. 13, 2025

What This Means For You

People who want to reduce their colon cancer risk and improve their health should cut down on the processed foods they eat daily.