Ultra-processed foods linked to early-onset colorectal adenomas in women

An increased risk of early-onset colorectal cancer (EOCRC) is associated with a high intake of ultraprocessed food (UPF) consumption, according to a recent study published in JAMA Oncology. Previously, obesity, sedentary behavior, Type 2 diabetes, and dietary patterns characterized by low fiber but high processed red meat and added sugars have all been identified as risk factors for EOCRC.

The rising incidence of EOCRC has become a pressing public health concern. Typically diagnosed before 50 years of age, EOCRC rates have climbed in high-income countries, including the United States, even among those without family history or genetic predisposition. Concurrent consumption of UPFs has also increased, “accounting for almost 60% of US adult energy intake.” This trend has prompted researchers to examine modifiable lifestyle and dietary factors that may contribute to disease risk.

Chen Wang, M.D., from the Harvard T.H. Chan School of Public Health and Massachusetts General Hospital, and his team analyzed data from the Nurses’ Health Study II, a large prospective cohort of female registered nurses. Between 1991 and 2015, a cohort of 29,105 women was observed, specifically including individuals who had undergone at least one lower endoscopy prior to the age of 50. Dietary intake was evaluated every four years through validated food-frequency questionnaires, with food items classified using the Nova system as unprocessed, processed or ultra-processed.

The primary outcome measured was the incidence of EOCRC precursors, including conventional adenomas and serrated lesions, verified via medical records and pathology reports. Investigators used multivariable logistic regression models to assess the relationship between UPF intake and the risk of these precursors, incorporating adjustments for established risk factors such as body mass index (BMI), type 2 diabetes, smoking status, physical activity and overall dietary quality.

Higher UPF intake was associated with increased risk of conventional adenomas. Women in the highest quintile of UPF consumption had 45% higher odds of developing adenomas compared with those in the lowest quintile (adjusted odds ratio [AOR], 1.45; 95% CI, 1.19-1.77; P < .001). No significant association was observed for serrated lesions. The risk did not differ across quintiles of UPF intake (AOR, 1.04; 95% CI, 0.89-1.22).

Dietary quality mattered, as participants with higher UPF intake also had lower fiber, folate, calcium and vitamin D intake and lower scores on the Alternative Healthy Eating Index-2010. Lifestyle differences were evident. High-UPF consumers were more likely to have a higher BMI, greater smoking exposure, type 2 diabetes and symptom-driven endoscopies, while being less likely to use multivitamins or undergo screening endoscopies.

EOCRC is increasingly recognized as a distinct clinical entity, often presenting in younger adults without traditional risk factors. Identifying modifiable exposures is crucial for prevention strategies. Widespread consumption of ultraprocessed foods, industrially manufactured products high in refined starches, unhealthy fats and additives, is not slowing down among U.S. adults.

Wang writes that UPFs may contribute to colorectal carcinogenesis by disrupting gut microbiota, promoting intestinal inflammation and reducing intake of protective nutrients. Supporting dietary quality improvement measures is one possible strategy, Wang suggests.

By focusing on precursors such as adenomas, this study provides an early window into how diet influences tumorigenesis before cancer develops. Given the increasing prevalence of EOCRC, enhancing dietary quality constitutes a practical and evidence-based approach to prevention.