A high consumption of ultra-processed foods increases the risk of colonic polyps, precursors of early-onset colorectal cancer, by 45%, according to a recent study.
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In a study of nearly 30,000 nurses under the age of 50, researchers at Mass General Brigham found that a high consumption of ultra-processed foods is associated with an increased risk of developing adenomas – colonic polyps that can be precursors to colorectal cancer.
Colorectal cancer was once considered a disease of old age, but diagnoses have become more common among adults 50 years of age or younger, especially in developed countries such as the United States.
The reason for this trend is unclear, but a new study led by Mass General Brigham researchers, part of the Cancer Grand Challenges PROSPECT team, suggests an important link to ultra-processed foods that deserves further investigation.
Analyzing the diets and endoscopy results of nearly 30,000 women, the team found that participants who reported the highest consumption of ultra-processed foods had a 45% higher risk of developing adenomas – precursors to early-onset colorectal cancer – compared to those who consumed the lowest amounts. The results were published in JAMA Oncology.
“Our findings support the importance of reducing consumption of ultra-processed foods as a strategy to reduce the growing burden of early-onset colorectal cancer”said lead author Andrew Chan, MD, MPH, chief of the Clinical and Translational Epidemiology Unit and gastroenterologist at Mass General Brigham Cancer Institute. “The increased risk appears to be fairly linear, meaning that the more ultra-processed foods you eat, the higher your risk of colon polyps.”
The consumption of ultra-processed foods—ready-to-eat products often high in sugar, salt, saturated fat, and food additives—has increased in parallel with the incidence of early-onset colorectal cancer (EOCRC). Dr. Chan’s research group has previously identified an association between ultra-processed foods and colorectal cancer in general, but this is the first study to link such foods to EOCRC.
How the study was conducted
The researchers analyzed data from the Nurses’ Health Study II, a long-term prospective study that followed nurses born between 1947 and 1964 — a generation known for its increased risk of early-onset colorectal cancer.
24 years of data from 29,105 nurses who performed at least two lower endoscopies before the age of 50 were analyzed for early detection of colorectal cancer precursors.
The participants also completed dietary questionnaires every four years, from which the researchers estimated their average daily intake of ultra-processed foods. Although diet was self-reported, this type of questionnaire has been validated and is considered relevant for the accurate reflection of dietary patterns.
On average, the participants consumed 5.7 servings of ultra-processed foods per day, accounting for 35% of total daily calories—slightly below the US national average.
Study results
Based on the results of the endoscopies, the researchers identified 2,787 participants who developed colorectal cancer precursor polyps. Women who ate the highest amounts of ultra-processed foods (an average of 10 servings per day) had a 45% higher risk of developing conventional adenomas — the precursor most associated with EOCRC — compared to those who ate the lowest amounts (an average of 3 servings a day).
However, no association was identified between consumption of ultra-processed foods and serrated lesions, another type of colorectal cancer precursor that develops more slowly and is less commonly associated with EOCRC.
“One of the strengths of our study is that we had detailed information on other risk factors for colorectal cancer, such as body mass index, type 2 diabetes or low fiber intake”said Dr. Chan. “Even after accounting for these factors, the association with ultra-processed foods remained.”
The authors point out that ultra-processed foods do not fully explain the increase in EOCRC cases, and researchers are working to identify other risk factors. It is also trying to improve the way ultra-processed foods are classified, as some products in this category could be more harmful than others.
“Diet does not fully explain this trend—we see many patients in our clinic with early-onset colorectal cancer who have very healthy diets”said Dr. Chan, who conducted this study as part of the Cancer Grand Challenges PROSPECT team. “Identifying other risk factors for early-onset colorectal cancer is one of the main directions of our research at Mass General Brigham Cancer Institute.”
