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Eat|Ultraprocessed Foods Linked to Colorectal Cancer Risk in Women Under 50
https://www.nytimes.com/2025/11/13/well/eat/ultraprocessed-foods-colorectal-cancer-risk.html
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The study’s findings track with recent research on the alarming rise of the cancer in younger adults.
Nov. 13, 2025, 11:03 a.m. ET
About 15 years ago, Dr. Andrew T. Chan, a gastroenterologist at Mass General Brigham in Boston, noticed that more of his colorectal cancer patients were skewing younger than usual. Some were in their 20s, 30s and 40s compared with his more typical patients in their 60s and 70s.
His observation was part of an alarming trend that experts are now racing to understand: Colorectal cancer rates have been mysteriously climbing among people under 50. In a study published today in JAMA Oncology, Dr. Chan and his colleagues suggest that ultraprocessed foods — which have increased in our diets over the decades — may be playing a role.
He and his team looked at women in their 20s, 30s and 40s. Those who ate more ultraprocessed foods had higher risks of developing precancerous colorectal polyps — abnormal clumps of cells that grow in the colon or rectum and can develop into cancer — before they turned 50 compared with those who consumed fewer. Ultraprocessed foods include sugary sodas, processed meats, candies, chips and other products made with ingredients you wouldn’t typically find in a home kitchen.
The study was large and was the first to look at how ultraprocessed foods may influence the development of colorectal polyps in people under 50, said Dr. Y. Nancy You, a colorectal surgeon at the University of Texas MD Anderson Cancer Center in Houston, who was not involved with the research. The findings add important context to the larger question of why colorectal cancer rates are rising in younger people, she said.
But the study also had limitations, Dr. You cautioned. While it found an association between ultraprocessed foods and precancerous polyps, it could not directly prove that eating the foods caused the growths.
What the New Study Concluded
From 1991 to 2015, researchers followed more than 29,000 female nurses who were in their mid-20s to early 40s at the start of the study. The nurses filled out detailed dietary questionnaires every four years, and all of them had at least one colonoscopy before age 50.
