A new study from Mass General Brigham has found a strong link between frequent consumption of ultraprocessed foods and a higher risk of early-onset colorectal cancer in adults under 50. The research, published in JAMA Oncology, examined data collected over more than 20 years from nearly 30,000 women who participated in the Nurses' Health Study II.
All participants, born between 1947 and 1964, underwent at least two lower endoscopies before age 50 and completed detailed dietary surveys every four years.
Researchers found that women who consumed around 10 servings of ultraprocessed foods per day had a 45% higher risk of developing adenomas - benign but precancerous growths in the colon or rectum - compared to those who consumed about three servings daily. These adenomas are known early indicators of colorectal cancer.
Ultraprocessed foods include many ready-to-eat products high in sugar, salt, saturated fat, and additives. Senior author Dr Andrew Chan said the findings highlight the need to reduce intake of these foods as part of cancer prevention efforts. He noted a “fairly linear” pattern: the more ultraprocessed foods people ate, the higher their risk of developing colon polyps.
While earlier studies have linked such foods to colorectal cancer overall, this is the first to directly connect them to early-onset cases. Researchers emphasized that diet alone does not fully explain the rise, and other factors - including metabolic disorders, genetics, and lifestyle - may also play a role.
In the US, colorectal cancer remains the third-most common cancer and the second-leading cause of cancer death, with an estimated 154,000 new cases and 52,900 deaths expected in 2025.
