A new study links high intake of ultra-processed foods (UPFs) to an increased risk of early-onset colorectal cancer (EOCRC) precursors in women, highlighting diet as a modifiable risk factor for a disease rising sharply in younger adults.
Published in JAMA Oncology, the research builds on prior evidence connecting EOCRC to obesity, sedentary lifestyle, type 2 diabetes, and diets low in fiber but high in processed meats and added sugars. EOCRC, typically diagnosed before age 50, has surged in high-income countries, including the United States, even among those without genetic predisposition. UPFs now account for nearly 60% of U.S. adult daily energy intake, prompting investigation into their potential role in disease development.
The study, led by Dr. Chen Wang of the Harvard T.H. Chan School of Public Health and Massachusetts General Hospital, analyzed data from 29,105 women in the Nurses’ Health Study II. Participants, all of whom had undergone at least one lower endoscopy before age 50, reported their diet every four years through validated food-frequency questionnaires. Foods were classified as unprocessed, processed, or ultra-processed using the NOVA system.
Researchers focused on EOCRC precursors, including conventional adenomas and serrated lesions, confirmed through medical and pathology records. Using multivariable logistic regression, the team adjusted for established risk factors such as body mass index (BMI), type 2 diabetes, smoking, physical activity, and overall diet quality.
Results showed that women with the highest UPF intake had a 45% higher likelihood of developing conventional adenomas compared with those in the lowest intake group (adjusted odds ratio [AOR], 1.45; 95% CI, 1.19–1.77; P < .001). No significant association was found for serrated lesions (AOR, 1.04; 95% CI, 0.89–1.22).
High-UPF consumers also had poorer overall dietary quality, with lower intake of fiber, folate, calcium, and vitamin D, and lower scores on the Alternative Healthy Eating Index-2010. They were more likely to have higher BMI, type 2 diabetes, greater smoking exposure, and symptom-driven endoscopies, while less likely to take multivitamins or undergo screening endoscopies.
Dr. Wang noted that UPFs may promote colorectal carcinogenesis by altering gut microbiota, increasing intestinal inflammation, and reducing intake of protective nutrients. By targeting precursors like adenomas, the study sheds light on how diet may influence tumor development before cancer occurs.
Given the growing prevalence of EOCRC and the widespread consumption of ultraprocessed foods, improving dietary quality represents a practical, evidence-based strategy for prevention.
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