In a major development, the connection between ultra-processed food consumption and early signs of colorectal cancer has been firmly established. According to a study published November 13, 2025, adults—specifically women under 50—who consumed high amounts of ultra-processed foods showed a significantly elevated risk of developing adenomas, the precancerous growths of colorectal cancer.
Table of Contents
Key Study Findings
- Researchers from Mass General Brigham analysed data on 29,105 women in the U.S., all of whom had at least two lower endoscopies before turning 50.
- On average the participants reported consuming 5.7 servings of ultra-processed foods per day, amounting to around 35% of total calories—slightly below typical U.S. averages.
- Women who reported 10 servings per day of ultra-processed foods (versus 3 servings for the lowest intake group) had a 45% higher risk of developing conventional adenomas.
- The association remained even after adjusting for other risk factors, such as body mass index (BMI), type 2 diabetes and fibre intake.
- Notably, the study found no significant association between ultra-processed food intake and the risk of serrated lesions—another type of polyp tied to colorectal cancer but less common in early onset cases.
What Counts As Ultra-Processed Foods?
The term “ultra-processed foods” refers to those that are ready-to-eat or ready-to-heat, often containing high levels of sugar, salt, saturated fats and chemical additives. Examples include frozen meals, processed meats, packaged snacks, sugary drinks and many convenience foods.
The dietary processing classification system known as NOVA categorises foods by the extent of processing—from unprocessed to ultra-processed—and ultra-processed foods sit at the highest level of industrial transformation.
Why This Matters for Early-Onset Colorectal Cancer
Historically, colorectal cancer (CRC) has been seen in older adults. However, incidence of early-onset colorectal cancer (diagnosed before age 50) has been rising in high-income countries like the U.S.
The current study suggests ultra-processed food consumption may help explain part of that rise. According to senior author Andrew T. Chan, MD, MPH:
“We’re seeing more cases of bowel cancer in younger adults, and we still don’t understand why… Our study suggests these foods could be linked to a higher risk of developing polyps.”
While this study does not demonstrate that ultra-processed foods directly cause colorectal cancer, the link with precancerous adenomas is a strong warning sign.
Study Limitations & Context
- The research focused on U.S. women (female nurses) under 50, so the findings may not generalise to men or to other demographic groups.
- Because diet data were self-reported via food-frequency questionnaires, measurement error is possible.
- The outcome measured was adenoma formation (precursor growths), not full-blown cancer. The pathway from adenoma to cancer can vary in timing and risk.
- The researchers emphasise that ultra-processed food intake alone does not account for the full rise of early-onset colorectal cancer; other risk factors are still under investigation.
Implications for U.S. Diet and Public Health
Given that many Americans derive a large share of their daily calories from ultra-processed foods, the implications are significant. While this study targets polyp risk in women under 50, the findings invite broader reconsideration of ultra-processed food consumption for the adult U.S. population.
Practical take-aways:
- Reducing ultra-processed food consumption may be a proactive strategy to lower adenoma risk.
- Emphasising minimally processed foods—vegetables, fruits, whole grains, lean proteins—supports gut health and may counteract some of the risks tied to ultra-processed foods.
- Early colon-screening discussions might need to include dietary history around ultra-processed food consumption, especially in younger adults.
- Public health campaigns may increasingly focus on ultra-processed foods as potential modifiable risk factors for colorectal harm.
Quick Reference: Key Stats from the Study
| Metric | Value |
|---|---|
| Number of women analysed | ~29,105 |
| Average servings/day | ~5.7 (≈35% of calories) |
| Highest intake group | ~10 servings/day |
| Lowest intake group | ~3 servings/day |
| Increased risk of adenoma | 45% higher in highest vs lowest intake |
What’s Next in Research?
Researchers with the PROSPECT team (part of the global Cancer Grand Challenges initiative) are already planning follow-up work that will:
- Explore ultra-processed food links in more diverse populations (including men, different racial/ethnic groups).
- Examine potential biological mechanisms (microbiome changes in the gut, inflammation, metabolic disruption) that might mediate the effect of ultra-processed foods on polyp formation.
- Investigate whether specific types or categories of ultra-processed foods carry higher risk than others.
In conclusion, this latest research adds compelling evidence that ultra-processed food consumption deserves serious attention in the context of colorectal health, especially for younger adults. We’d love to hear your thoughts or experiences—please leave a comment below and keep following for updates on this evolving topic.