The rise of colorectal cancer in younger adults has puzzled researchers for years, and the numbers keep climbing. At the same time, ultra-processed foods have taken over diets across many countries, now making up nearly 70 percent of the U.S. food supply and close to 60 percent of the average American adult’s daily calories. With both trends moving in the same direction, scientists have been increasing their focus on how these foods may shape long-term health. Recent research has delivered findings that strengthen the concern, especially as more teams study the early steps that lead to cancer.
The Growing Evidence Linking UPFs To Cancer Risk
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Several major studies released in 2025 drew wide attention for their findings on ultra-processed foods, often referred to as UPFs under the NOVA classification system.
These foods rely heavily on industrial techniques and additives, including preservatives, emulsifiers, gelling agents, bleaching agents, and flavor enhancers. They tend to be low in fiber and high in refined grains, added sugars, calories, sodium, and fats. Many also include ingredients that rarely appear in home cooking.
Two extensive studies have stood out for the strength of their data.
The first study was part of the Norwegian Women and Cancer Study, which followed more than 77,000 women for an average of 17.4 years. After analyzing diets and classifying foods according to their level of processing, researchers found that high UPF intake was associated with a higher risk of overall colorectal cancer. The increased risk was especially pronounced for right-sided colon cancer. Women consuming more than 466 grams of UPFs daily showed a 58 percent higher risk for cancers in that region compared with those who consumed 274 grams or less.
The second study, published in JAMA Oncology, followed more than 29,100 U.S. nurses for about 13 years. Instead of looking at cancer cases, it examined noncancerous colorectal adenomas, growths that can later progress to cancer if untreated.
Participants who consumed the highest levels of UPFs had a 45% higher risk of developing these adenomas before the age of 50 than those with the lowest intake. UPF consumption mainly came from packaged breads and breakfast items, sauces, condiments, and sugar-sweetened or artificially sweetened drinks.
These findings shed light on a pattern that researchers have suspected for years: diets dominated by ultra-processed foods may play a role in the early stages of colorectal cancer development.
Scientists Are Concerned About These Foods
The potential pathways are becoming clearer. UPFs can alter the gut microbiome and weaken the intestinal lining’s protective barrier. This combination may lead to increased inflammation over time. When these foods are broken down in the body, some can produce harmful byproducts that irritate cells in the colon and rectum.
Researchers also highlight the possible influence of ingredients such as seed oils rich in omega-6 fatty acids, which are extremely common in UPFs. Beyond direct biological effects, UPF-heavy diets often lead to weight gain. Obesity is a known risk factor for colorectal cancer.
Scientists emphasize that the studies so far don’t establish direct causation, but the strength and consistency of the associations are signaling a problem worth serious attention.
Understanding The Research Limitations
Nutrition studies always carry challenges, and the scientists behind these projects acknowledge them openly.
Much of the dietary information was obtained from food-frequency questionnaires, which rely on individuals recalling their habits over the prior year. These studies also focused on specific populations, primarily female nurses in the U.S. and women in Norway. Hence, the findings cannot be automatically applied to all populations or countries. Additionally, the studies employed different endpoints, with one tracking cancer cases and the other tracking benign tumors.
Even with these limitations, the associations remained after adjusting for factors such as age, smoking, exercise, education, and total calorie intake. Researchers agree that larger, more diverse studies are needed, along with lab-based work to understand the mechanisms underlying these results.
How Ultra-Processed Foods Took Over Modern Diets
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The rapid rise of UPFs has changed the way people eat. These products are inexpensive, convenient, widely marketed, and engineered for taste and shelf stability.
Sauces, packaged breads, frozen meals, sweetened drinks, flavored snacks, breakfast bars, and many other items fall into this category.
Since these products are designed to be appealing, they often encourage frequent snacking and make it easy to exceed calorie intake without noticing. Their structure and added ingredients can also reduce satiety compared with whole foods.
What These Findings Mean For Everyday Eating
Scientists aren’t calling for perfection or a complete removal of UPFs. Instead, experts suggest being mindful of how often these products appear in meals and snacks.
Diets focused on fruits, vegetables, whole grains, legumes, nuts, seeds, and minimally processed foods consistently show better long-term outcomes in research. It’s not new guidance, but the emerging cancer data has given it renewed urgency. It also highlights structural issues in food access.
Many people rely on UPFs because they are the most affordable or accessible options in their communities. Public health specialists point out that creating healthier food environments is as important as individual dietary choices.
What Researchers Want People To Know
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Scientists agree that the growing body of evidence is concerning enough.
Reducing UPF intake, when possible, may help lower the likelihood of developing the types of polyps that can turn into cancer, especially for people under age 50 who are seeing rising rates of colorectal disease.
Early screening remains essential. Several symptoms, including dark or bloody stools, unexplained weight loss paired with digestive discomfort, anemia, or persistent changes in bowel habits, should prompt a medical visit. Screening starting at age 45 can detect problems before they become dangerous.
The rise in early-onset colorectal cancer is complex, and UPFs are only one piece of a much larger puzzle. Researchers are exploring lifestyle, environmental exposures, changes in the microbiome, medications, additives, and many other factors.