By Lew Kizer — 2026-10-17 — Health & Nutrition
The short answer
In a PLOS Medicine study published October 15, 2026, National Cancer Institute researchers followed 461,682 U.S. adults aged 50 to 71 for a median of 18.8 years. Total ultra-processed food intake was not associated with colorectal cancer (highest vs. lowest fifth: HR 0.97). But fiber, whole grains, dairy and calcium were linked to lower risk, and processed meat to higher risk, whether or not those foods were classified as ultra-processed.
Key facts
- 461,682 adults in the NIH-AARP Diet and Health Study; 10,075 colorectal cancer cases.
- Median follow-up 18.8 years; diet measured once in 1995–96.
- Total ultra-processed food: HR 0.97 (95% CI 0.91–1.03), no association.
- Fiber from ultra-processed sources: HR 0.72 per 10 g/day; reconstituted meat and fish products: HR 1.10.
- Meat was linked to higher risk from both processed (HR 1.08) and non-processed sources (HR 1.04) per daily serving.
- Observational study in an older, mostly white cohort; it cannot prove cause and effect.
KINGSPORT, Tenn., Oct. 17, 2026 — Ultra-processed food has become shorthand for everything wrong with the modern diet. A major new study from the National Cancer Institute says the picture, at least for colorectal cancer, is more complicated.
This article reports research and is not medical advice. Talk with your doctor about colorectal cancer screening.
The headline finding
Researchers analyzed 461,682 adults aged 50 to 71 who joined the NIH-AARP Diet and Health Study in 1995–96. Over a median of 18.8 years, 10,075 developed colorectal cancer. People who ate the most ultra-processed food were no more likely to develop it than those who ate the least (hazard ratio 0.97). The result held for the colon and rectum separately.
What sat inside the averages
When the researchers broke ultra-processed food into its parts, the pieces pulled in different directions:
| Food or nutrient | Association with colorectal cancer |
|---|---|
| Fiber from ultra-processed sources (per 10 g/day) | Lower risk (HR 0.72) |
| Whole grain from ultra-processed sources (per serving/day) | Lower risk (HR 0.87) |
| Dairy, any source (per serving/day) | Lower risk (HR 0.75–0.90) |
| Reconstituted meat and fish products (top vs. bottom fifth) | Higher risk (HR 1.10) |
| Meat, processed or not (per serving/day) | Higher risk (HR 1.04–1.08) |
People with poor overall diet quality had higher risk even at moderate ultra-processed intake. Replacing 10% of ultra-processed food grams with minimally processed food was linked to slightly lower risk (HR 0.98).
Limits the authors flag
Diet was measured once, nearly 30 years ago, using a questionnaire not designed to capture processing. The cohort was older and mostly white. The study could not examine additives. As an observational study, it shows associations, not cause and effect.
The practical takeaway
The authors say their results support existing advice: eat whole grains, fiber, dairy and calcium, and limit processed meat. If you eat gluten-free, look for naturally gluten-free whole grains such as brown rice and quinoa, plus beans and vegetables. Our new guide to closing the fiber gap shows how, and a companion study on how ultra-processed meals affect insulin adds another angle.
Browse this week's meals and check the fiber on each label.
Commentary, not medical advice
The SmashMeals perspective
We like this study because it refuses the easy headline. A label like “ultra-processed” is a starting point; what the food actually delivers is what counts. For colon health, the evidence keeps pointing to fiber, whole grains, dairy and calcium, and to going easy on processed meat. We build meals around real protein and vegetables, and our posted nutrition shows the fiber in each one.
Frequently asked questions
Does ultra-processed food cause colon cancer?
In this large NIH study, total ultra-processed food intake was not associated with colorectal cancer. The authors suggest that is partly because ultra-processed foods include items linked to both higher risk (processed meat) and lower risk (high-fiber breads and cereals).
What foods were linked to lower colorectal cancer risk?
Higher fiber, whole grains, dairy and calcium were associated with lower risk. These were observational associations, not proof.
Should I still limit ultra-processed food?
This study looked at one cancer. Other research links some ultra-processed foods to other health problems. A practical approach is to focus on fiber, protein and vegetables and limit processed meat and sugary drinks.
Sources and credits
Follow the original sources for context and verification. A reference is not an endorsement of SmashMeals.
- Associations of food processing and dietary risk factors with colorectal cancer incidence in the NIH-AARP Diet and Health Study (opens in a new tab)
PLOS Medicine
Why it matters: The peer-reviewed study and all hazard ratios cited here.
- Total ultra-processed food intake not linked to colorectal cancer in large US cohort study (opens in a new tab)
Medical Xpress
Why it matters: News summary of the findings.