Ultraprocessed Foods Linked to Higher Risk of Early-Onset Colorectal Adenomas

Women under age 50 who consume higher amounts of ultraprocessed foods (UPFs) face significantly increased odds of developing early-onset colorectal adenomas, according to findings from a recent US cohort study.¹ These findings reinforce concerns that UPFs may contribute to rising colorectal cancer (CRC) rates among younger adults.

The prospective cohort study is published in JAMA Oncology.

“The global incidence of early-onset colorectal cancer (EOCRC), diagnosed before age 50 years, has increased over recent decades, especially in high-income countries such as the US,” wrote the researchers of the study. “This trend reflects birth-cohort effects, particularly among those born in or after 1960. Given that EOCRC often occurs in individuals without family history of or identifiable genetic predisposition to CRC, modifiable environmental and lifestyle exposures may have outsized effects on its development.”

UPFs make up a majority of daily calorie intake in the US, accounting for about 62% of children and teens’ calories and 53% for adults, according to the CDC.² Common sources include burgers, hot dogs, peanut butter and jelly sandwiches, salty snacks, sugary drinks, and baked goods. While intake has slightly decreased in recent years, the findings underscore the need for targeted efforts to reduce harmful UPFs in American diets, particularly among children, while distinguishing healthier options from those that pose risks.

The study drew on data from the Nurses’ Health Study II (NHS II), a large ongoing US cohort of female registered nurses established in 1989.¹ Researchers followed participants from 1991 to 2015 and included women who completed the baseline food-frequency questionnaire and underwent at least 1 lower endoscopy before age 50.

UPF intake was assessed every 4 years using validated questionnaires and categorized into quintiles based on energy-adjusted servings per day. Early-onset colorectal neoplasia—conventional adenomas and serrated lesions—was confirmed through medical records and pathology reports. The team calculated adjusted ORs (AORs), accounting for established and potential risk factors, including lifestyle characteristics, medical history, and dietary variables.

Over 24 years of follow-up among 29,105 women (mean [SD] age, 45.2 [4.5] years), the study identified 1189 cases of early-onset conventional adenomas and 1598 serrated lesions. UPFs accounted for a median (IQR) of 5.7 (4.5-7.4) servings per day, representing 34.8% of total daily calories.

Women in the highest quintile of UPF consumption had 45% higher odds of developing early-onset conventional adenomas compared with those in the lowest quintile (AOR, 1.45; 95% CI, 1.19-1.77; P < .001). In contrast, no significant association was observed for serrated lesions (AOR, 1.04; 95% CI, 0.89-1.22; P = .48). These associations persisted even after adjusting for body mass index, type 2 diabetes, dietary quality, and micronutrient intake.

However, the researchers acknowledged several limitations, which include using precursor lesions rather than EOCRC due to few cancer cases, potential misclassification of UPFs despite detailed subgrouping, and a cohort of mostly well-educated female nurses, which may have limited generalizability. Furthermore, residual confounding could be ruled out, warranting further study in diverse populations.

Despite these limitations, the researchers believe these findings suggest reducing UPF intake may be effective in preventing EOCRC.

“In this study, higher UPF intake was associated with increased risk of early-onset colorectal conventional adenomas in a cohort of 29,105 female nurses in the NHS II,” wrote the researchers. “Our findings highlight the importance of diet in early-onset colorectal carcinogenesis and support dietary quality improvement as a strategy to mitigate the increasing burden of EOCRC.”

References

1. Wang C, Du M, Kim H, et al. Ultraprocessed food consumption and risk of early-onset colorectal cancer precursors among women. JAMA Oncol. Published online November 13, 2025. doi:10.1001/jamaoncol.2025.4777

2. Bonavitacola J. Children’s diets primarily made up of ultra-processed foods, finds CDC. AJMC^®. August 7, 2025. Accessed November 18, 2025. https://www.ajmc.com/view/children-s-diets-primarily-made-up-of-ultra-processed-foods-finds-cdc