A new study published in JAMA Oncology has identified ultra-processed foods as a potential driver of the rising colon cancer rates among women under 50. Researchers analyzed data from nearly 30,000 women over 24 years and found that those who consumed the highest amounts of these foods had a 45 percent higher risk of developing precancerous polyps.
Researchers tracked nearly 30,000 women for more than two decades
The study used data from the Nurses’ Health Study II, which has followed the health and lifestyle habits of tens of thousands of women since 1989. For this analysis, researchers focused on 29,105 female participants under 50 who had completed detailed food questionnaires, undergone at least one lower endoscopy, and had no prior history of cancer, inflammatory bowel disease, or colorectal polyps at the start of the study.
Every four years, the women reported how often they ate various foods. Researchers categorized the foods based on their level of industrial processing. Ultra-processed foods include packaged breads, sweetened beverages, flavored yogurts, breakfast cereals, snack foods, and ready-to-eat meals. These items are often calorie-dense, low in nutrients, and contain additives to improve taste, texture, or shelf life.
The findings reveal a clear relationship
Women who consumed the most ultra-processed foods, about 5.7 servings per day or roughly one-third of their daily calories, had a 45 percent higher risk of developing precancerous polyps compared to those who ate the least. The link was specific to conventional adenomas, the type of polyp most likely to turn into colorectal cancer over time. Researchers did not find the same association with serrated lesions, another type of polyp.
The foods most strongly tied to increased risk included sugar-sweetened beverages, ready-to-eat meals, processed meats such as hot dogs and deli slices, breakfast cereals, packaged breads, and bottled condiments. These convenience foods are common in many weekly shopping carts.
A related article notes that many colon cancer cases are preventable and lists ways to reduce risk.
Why ultra-processed foods might be driving precancerous changes
Scientists do not yet know with certainty that ultra-processed foods directly cause colorectal cancer, but they have strong hypotheses. Ultra-processed foods are known to trigger chronic low-grade inflammation throughout the body, including in the gastrointestinal tract. Inflammation can create an environment where cells accumulate DNA damage and mutations, which are early steps toward cancer.
These foods also disrupt the gut microbiome. They tend to be low in fiber and high in additives like emulsifiers and artificial sweeteners, which can reduce microbial diversity and promote harmful bacteria. Additionally, many ultra-processed foods contain advanced glycation end products, compounds formed when proteins or fats combine with sugars during high-heat processing. These compounds accumulate in body tissues and are linked to oxidative stress and inflammation.
What this means for women’s health and how to take action
With early-onset colorectal cancer rising and routine screening not recommended until age 45, prevention becomes important. The study authors suggest several practical shifts in daily eating habits.
Reducing ultra-processed staples, not just snacks, is key. Packaged breads, sweetened yogurts, cereals, flavored coffee creamers, and bottled sauces were major contributors to ultra-processed food intake in the study. Prioritizing fiber-rich whole foods, aiming for 25 to 35 grams daily from vegetables, beans, whole grains, berries, nuts and seeds, helps feed the gut microbiome and support digestion. Keeping sugary drinks to a minimum is also recommended, as they were a consistent contributor to ultra-processed intake and have been tied to metabolic and digestive disturbances.
Choosing items with shorter ingredient lists when possible is another step. If the ingredient panel reads like a chemistry set, the product is more likely to be ultra-processed. Knowing the warning signs is also important: persistent changes in bowel habits, blood in the stool, unexplained weight loss, ongoing abdominal cramping, or unusual fatigue should prompt a conversation with a doctor, regardless of age. When caught early, colorectal cancer has a survival rate above 90 percent.
The takeaway
The study focused exclusively on white female nurses, so more diverse research is needed to understand how these findings apply across different racial, ethnic, and socioeconomic groups. The relationship between diet and disease does not affect everyone equally; genetics, access to healthcare, environmental factors, and cultural food traditions all play roles.
The core message is that diet is changing cancer risk, potentially decades before symptoms appear. The rise in early-onset colorectal cancer is happening alongside dramatic shifts in food production and consumption. Dietary choices made today lay the groundwork for health in the future.
Source: JAMA Oncology, https://jamanetwork.com/journals/jamaoncology/article-abstract/2841354
