A new analysis found an association between high intake of ultra-processed foods and precancerous colon polyps in women under 50. Women with the highest consumption of ultra-processed foods had about a 45% greater risk of developing conventional adenomas — polyps that can progress to colorectal cancer — compared with women who ate the fewest ultra-processed foods. The report was published November 13, 2025, in JAMA Oncology.
Study and methods
Researchers analyzed records from more than 29,000 participants in the Nurses’ Health Study II, a cohort of female nurses who provided baseline data in 1991 and periodic diet questionnaires every four years. The investigators reviewed data collected between 1991 and 2015, with a median follow-up of 13 years. Participants were, on average, 45 years old during follow-up and had undergone at least one lower endoscopy before age 50. Those with a prior cancer history (other than nonmelanoma skin cancer) before their endoscopy were excluded.
Ultra-processed food intake in this study primarily included processed breads, many breakfast foods, sauces, spreads, condiments, and sugar-sweetened or artificially sweetened beverages. The highest category of consumption was about 10 servings per day versus about three servings per day in the lowest category.
Findings
Among study participants, 1,189 were documented as having early-onset conventional adenomas and 1,598 had serrated lesions during follow-up. Higher ultra-processed food intake was associated with an increased risk of conventional adenomas by age 50, but the researchers did not find a link between ultra-processed foods and serrated lesions.
Interpretation and expert reactions
Authors of the study concluded that these data highlight a potential role for ultra-processed foods in early-onset colorectal tumorigenesis and support improving dietary quality to help reduce the rising burden of colorectal cancer in younger adults.
Independent experts said the findings align with prior research linking diet and other lifestyle factors to increased colorectal cancer risk in younger people. Katherine Van Loon, MD (gastrointestinal cancer specialist), noted a global rise in colorectal cancer among younger adults and said diet, obesity, and environmental exposures are likely contributors. Kristin Kirkpatrick, RD, emphasized that the results are consistent with evidence showing adverse effects from high ultra-processed food consumption. Caroline Um, PhD, MPH (American Cancer Society), said limiting ultra-processed foods and emphasizing whole, nutrient-rich items are consistent with cancer prevention guidelines.
Some experts cautioned about generalizing the results. Tracey Childs, MD, pointed out the study only included women, so it cannot directly assess whether men have similar risks. Others noted limitations related to self-reported dietary questionnaires and a broad definition of “ultra-processed,” which in this study included alcohol — a known independent cancer risk factor. Authors and commentators suggested future work should examine ultra-processed food effects with and without alcohol included.
Context and related research
Colorectal cancer remains common: CDC data reported nearly 150,000 U.S. cases in 2022 and more than 50,000 deaths in 2023, with men experiencing higher incidence and mortality than women overall. While incidence has declined in people 65 and older and remained stable for ages 50–64, cases have been rising among adults under 50, roughly 2% per year in some age bands. Prior studies have linked obesity and diabetes with higher colorectal cancer risk in younger adults. Other recent research, including large cohort studies, has also associated ultra-processed food consumption with increased colorectal cancer risk in men and women and with substantial numbers of preventable deaths.
Estimates suggest a large proportion of the U.S. food supply and caloric intake is ultra-processed: Food Tank has estimated about 73% of the U.S. food supply is ultra-processed, and some research indicates almost 60% of U.S. adults’ calories come from ultra-processed foods.
Why ultra-processed foods may raise risk
Ultra-processed foods are industrially produced items formulated for long shelf life and convenience and typically contain refined starches, unhealthy fats, added sugars, and a variety of additives (emulsifiers, artificial sweeteners, etc.) while being low in fiber, vitamins, and polyphenols. Study authors and independent experts suggested these characteristics could alter the gut microbiome, increase intestinal inflammation, promote excess calorie intake and weight gain, and thereby contribute to colorectal carcinogenesis. The roles of specific additives and long-term effects remain incompletely understood.
Recommendations
The American Cancer Society and other experts recommend dietary and lifestyle approaches to reduce cancer risk for adults, including:
– Emphasize nutrient-rich foods to help maintain a healthy body weight.
– Eat a variety of colorful vegetables and fruits.
– Choose whole grains.
– Limit red and processed meats, sugar-sweetened beverages, highly processed foods and refined grains, and alcohol.
– Maintain a healthy weight, be physically active, and reduce sedentary time.
Experts note that occasional indulgence is unlikely to be harmful, but frequent consumption of ultra-processed foods appears to carry greater risk. Practical advice includes choosing whole-grain options, fruits and vegetables for sweetness and fiber, and minimizing routine reliance on processed convenience foods.
Limitations and next steps
Key limitations of the study include its observational design, reliance on self-reported diet, a somewhat broad definition of ultra-processed foods that included alcohol, and that it only included women. Future studies in diverse populations, including men, with refined exposure definitions and mechanistic research on microbiome and additive effects, are needed to confirm the findings and clarify causal pathways.
Bottom line
This study adds to growing evidence that high consumption of ultra-processed foods may be linked to early development of colorectal cancer precursors in younger adults, at least in women, and supports public-health and individual recommendations to favor whole, nutrient-dense foods and limit highly processed products.
