New research suggests that women under 50 who consume high amounts of ultra-processed foods (UPFs) face a significantly increased risk of developing abnormal bowel growths that can precede cancer. The findings add to a growing body of evidence connecting UPFs to serious long-term health issues, including metabolic disorders and chronic inflammation.
Understanding Ultra-Processed Foods
UPFs are industrially formulated products, typically low in whole ingredients, fiber and micronutrients, while high in additives, sugar, saturated fats and salt. Although some debate remains about whether all UPFs are harmful, numerous studies have linked high consumption to heart disease, obesity and premature mortality.
The latest study focused specifically on the relationship between UPFs and early-onset intestinal abnormalities, notably conventional adenomas — common precancerous polyps that can serve as early indicators of colorectal cancer development.
Study Design and Key Findings
Published in JAMA Oncology, the study analyzed data from the long-running Nurses’ Health Study II, involving more than 29,000 female participants. Between 1991 and 2015, researchers tracked dietary patterns through recurring food questionnaires and compared these with colonoscopy findings.
Participants were grouped into five categories of UPF consumption. Women consuming the highest amounts — an average of 9.9 servings per day — showed a 45 percent increased risk of developing early-onset conventional adenomas compared with those consuming the least, averaging 3.3 servings per day. This association remained even after adjusting for BMI, smoking, physical activity and other lifestyle factors.
No similar association was found for serrated lesions, another type of bowel polyp. Researchers emphasized that while most polyps do not progress to cancer, the majority of colorectal cancers in younger adults originate from these early lesions.
Potential Biological Mechanisms
Although the findings do not demonstrate causation, the researchers identified several plausible explanations. UPF-heavy diets have previously been linked to metabolic conditions including obesity and type 2 diabetes, both recognized as risk factors for colorectal cancer. Other possible mechanisms include chronic low-grade inflammation, disruptions to gut microbiota and compromised gut-lining integrity.
Experts caution that food classification challenges and reliance on self-reported dietary data present limitations. Additionally, the study did not track actual cancer incidence, focusing instead on early precancerous markers.
Implications for Public Health
While the study emphasizes that eating UPFs does not guarantee disease development, it contributes important context to rising colorectal cancer rates among younger adults. Health organizations stress that dietary patterns as a whole matter more than any individual food category.
Public health experts, including representatives from Cancer Research UK, note that structural, policy-level efforts are needed to ensure widespread access to healthier food choices. Further research is expected to explore whether the findings apply equally to men and to clarify the biological links between UPFs and cancer development.
Conclusion
The study offers a significant insight into how diets rich in ultra-processed foods may influence early changes in the bowel that precede colorectal cancer, especially among women under 50. While more evidence is needed, the findings reinforce the importance of maintaining balanced, nutrient-rich diets and reducing reliance on heavily processed foods.