A new study published November 13, 2025, in JAMA Oncology found an association between ultra-processed food intake and the risk of precancerous colorectal polyps in women under 50. Women with the highest intake of ultra-processed foods had a 45% higher risk of developing conventional adenomas—polyps that can progress to colorectal cancer—compared with women with lower intake.
Study design and findings
Researchers analyzed medical records and dietary data from more than 29,000 female nurses in the Nurses’ Health Study II. Participants provided baseline data in 1991 and completed follow-up questionnaires about their diet every four years through June 2015, with a median follow-up of 13 years. All participants had at least one lower endoscopy before age 50 and no prior history of cancer (except nonmelanoma skin cancer).
Ultra-processed food intake in the study mainly came from processed breads, breakfast foods, sauces, spreads, condiments, and sugar-sweetened or artificially sweetened beverages. The highest intake group averaged about 10 servings per day; the lowest intake group averaged about three servings per day. During follow-up, researchers documented 1,189 cases of early-onset conventional adenomas and 1,598 serrated lesions. High ultra-processed food intake was associated with increased risk of adenomas but not with serrated lesions.
Limitations
Experts noted several limitations: the study included only women, dietary data were self-reported, and the definition of “ultra-processed” was broad. Alcohol was counted as an ultra-processed food in this analysis, and because alcohol independently raises cancer risk, future studies should examine ultra-processed food intake with and without alcohol.
Expert reactions and context
Outside experts said the findings align with previous research linking unhealthy diets, obesity, and environmental exposures to rising colorectal cancer rates in younger adults. They highlighted potential mechanisms—ultra-processed foods are typically low in fiber, vitamins, and polyphenols and high in unhealthy fats, refined starches, and additives (emulsifiers, artificial sweeteners) that may disrupt gut microbiota and increase intestinal inflammation, promoting carcinogenesis. Ultra-processed foods can also promote excess calorie intake and weight gain, which are established colorectal cancer risk factors.
Previous studies have linked ultra-processed food consumption to increased colorectal cancer risk in men and women and to substantial numbers of preventable deaths in the U.S. Food-supply estimates and dietary surveys suggest a large share of U.S. calories come from ultra-processed foods.
Public health context and recommendations
The CDC reported nearly 150,000 colorectal cancer cases in the U.S. in 2022; more than 50,000 people died from the disease in 2023. While incidence and mortality remain higher in men overall, colorectal cancer rates have been rising in younger adults—about 2% per year for some age groups—and earlier onset is a growing concern.
The American Cancer Society and other experts recommend limiting ultra-processed foods and emphasizing whole, nutrient-rich options to reduce cancer risk. Key dietary and lifestyle recommendations include:
– Eat a variety of vegetables and fruits and choose whole grains.
– Favor nutrient-rich foods that support a healthy body weight.
– Limit red and processed meats, sugar-sweetened beverages, highly processed foods, refined grain products, and alcohol.
– Maintain a healthy body weight, be physically active, and reduce sedentary time.
Practical advice from clinicians emphasizes frequent healthy eating over occasional indulgences: occasional processed-food treats are less concerning than frequent consumption. Further research is needed to confirm mechanisms, examine effects in men, and separate the role of alcohol from other ultra-processed foods.
