A recent study from Mass General Brigham, published in JAMA Oncology, shows a strong association between high consumption of ultra-processed foods (UPF) and an increased risk of adenomas, or pre-cancerous polyps, in women under the age of 50.
The study found that participants who consumed around 10 servings of UPF per day had a 45% higher risk of developing adenomas compared to those who consumed about three servings per day.
Adenomas are benign growths in the colon and rectum, but they are considered early indicators that can develop into colorectal cancer later in life. These findings are significant given that colorectal cancer is one of the most common cancers and the second leading cause of cancer-related deaths in the United States.
More UPFs, Higher Polyp Risk
The research drew on long-term data from nearly 30,000 women enrolled in the Nurses’ Health Study II, a major cohort study involving participants born between 1947 and 1964. All participants had undergone at least two lower endoscopies before turning 50 and completed dietary surveys every four years.
Over more than two decades of follow-up, the study recorded 1,189 cases of conventional adenomas and 1,598 cases of serrated lesions. The results showed that the association with UPF appeared only for conventional adenomas, while serrated lesions did not show a similar link.
Researchers emphasized a “linear” pattern of increased risk, meaning that higher UPF consumption corresponded directly with higher likelihood of developing polyps.
The Issues Behind Ultra-Processed Foods
The UPF category in this study included processed breads, instant breakfast foods, various sauces and condiments, as well as sugary drinks and beverages with artificial sweeteners. These products are typically produced through industrial processes and often contain ingredients not commonly used in home cooking.
Their characteristics include high levels of sugar, salt, saturated fats, and industrial additives such as preservatives, emulsifiers, stabilizers, and colorants. In addition to being low in fiber and high in calories, UPFs are linked to metabolic disorders such as obesity and type 2 diabetes, both of which have long been known to increase colorectal cancer risk.
In this study, UPFs were identified as one of the factors contributing to metabolic conditions that may influence the development of pre-cancerous polyps.
UPFs Are a Key Factor, but Not the Only One
Although UPF is a significant factor, the researchers emphasize that diet is not the sole cause behind the growing number of colorectal cancer cases in younger adults. Genetic predisposition, lifestyle changes, metabolic disorders, and shifts in gut microbiota composition are also believed to contribute.
However, this study is particularly important because it is the first to link UPF consumption with precursors of colorectal cancer that appear at a young age—not just with cancer occurrence in general.
The researchers also noted that most polyps were detected before 2015, during a time when the recommended age for colorectal cancer screening was still 50. This suggests that many participants underwent earlier examinations due to additional risk factors.
Methodological Considerations and Study Limitations
As with other nutrition studies, this research has limitations. Dietary intake data were collected from participants’ recollections through questionnaires, which means some degree of inaccuracy is unavoidable.
The classification of UPF itself remains debated in the scientific community due to the complexity of products and the diversity of processing methods. In addition, the study included only women, meaning further research is needed to determine whether similar patterns apply to men.
The researchers stressed that even after adjusting for other factors—such as body mass index, physical activity, and smoking habits—the association between UPF consumption and adenomas remained consistent. This strengthens the suspicion that UPFs have a biologically relevant influence on the formation of pre-cancerous polyps.
Global UPF Consumption Aligns with Growing Cancer Cases
The rise of early-onset colorectal cancer has occurred alongside a global increase in UPF consumption, especially in the United States. UPFs now account for about 70% of the national food supply and nearly 60% of total adult calorie intake.
By 2025, an estimated 154,000 new cases of colorectal cancer and about 52,900 related deaths are expected. These figures show how serious the disease burden is and how modern diets may be accelerating this trend.
Experts also stress the need for policy changes and broader access to healthy foods to help communities reduce dependence on heavily processed products.
A Strong Warning Signal on UPFs
Funded by Cancer Research UK, the National Institutes of Health/National Cancer Institute, and the American Cancer Society, this study provides an important piece of the puzzle in understanding what is driving the increase in colorectal cancer among younger generations.
While it does not claim that UPF consumption automatically causes cancer, the findings indicate that highly processed foods may play a significant role in the formation of polyps, which represent the earliest stage in the development of cancer.
