Colorectal cancer is striking younger Americans at a disturbing pace — and a major new study suggests ultraprocessed foods may be one reason why.
Ultra processed foods (UPFs) now make up about 70% of the U.S. food supply and nearly 60% of adult calorie intake. As their popularity has exploded, so have cases of colon and rectal cancers in people under 50.
A first-of-its-kind study in JAMA Oncology followed more than 29,100 female nurses for a median of 13 years and found women who ate about 10 servings of ultraprocessed foods per day faced a 45% higher risk of developing early-onset colorectal adenomas — the precancerous polyps that can lead to cancer — compared with those eating just over three servings.
The biggest culprits included ultraprocessed breads and breakfast foods, condiments and sauces, and sugar-sweetened or artificially sweetened beverages.
Even after accounting for obesity, type 2 diabetes, and low fiber intake, the association held firm.
Why These Foods May Be a Problem
Ultraprocessed foods are typically low in fiber and high in added sugars, sodium, refined grains, additives, and omega-6-rich seed oils. These industrial ingredients can disrupt the gut lining, alter the microbiome, trigger inflammation, and create harmful metabolites during digestion.
The study linked UPFs specifically to classic adenomas, but not to serrated lesions — suggesting they may influence a particular pathway toward colon cancer.
Most adenomas in the study were found before the routine screening age dropped from 50 to 45, meaning many were discovered because of symptoms or family history.
Researchers also note that ultraprocessed foods from the 1990s weren’t identical to today’s versions, which now contain new additives and updated formulations.
What to Watch For
Precancerous colorectal growths often cause no symptoms, but larger ones can lead to:
Dark or bloody stools
Abdominal pain
Iron-deficiency anemia
Unintended weight loss
Constipation caused by a blockage
Screening is recommended starting at age 45, or earlier if there is a family history.
The Bottom Line
This study doesn’t prove causation — but it adds robust evidence that diets high in ultraprocessed foods may set the stage for early colorectal changes at a time when young-onset cancer rates are rising sharply.
Medical Disclaimer: This article is for informational and educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional regarding any medical concerns or dietary changes.
