Large US Cohort Study Finds No Overall Link Between Ultra-Processed Food and Colorectal Cancer

Ultra-processed foods have become the villain of modern nutrition science, blamed for everything from obesity to heart disease. But a sweeping new investigation of more than 400,000 American adults suggests the story is far more complicated than a simple warning label could convey. In a study published October 15 in the open-access journal PLOS Medicine, Erikka Loftfield of the National Cancer Institute and colleagues report that total ultra-processed food intake was not associated with an increased incidence of colorectal cancer, one of the most common and deadly malignancies in the United States. The finding challenges the increasingly popular assumption that the degree of industrial processing alone determines whether a food harms or protects the body.

Ultra-processed foods, defined under the widely used NOVA classification system as industrial formulations assembled largely from substances derived from foods plus additives, flavorings, and cosmetic ingredients, now account for more than half of the energy intake among U.S. adults. Their rapid displacement of freshly prepared meals has coincided with rising rates of several chronic diseases, and observational studies have repeatedly linked high UPF consumption to elevated risks of cardiovascular disease, type 2 diabetes, and certain cancers. Colorectal cancer has been of particular interest because diet is one of its few modifiable risk factors, and because incidence in younger adults has been climbing for reasons that remain poorly understood. Yet the new analysis indicates that the processing category itself may be a poor predictor of cancer risk when the nutritional character of the foods within it is taken into account.

To untangle these relationships, the research team turned to one of the largest dietary cohorts ever assembled: the NIH-AARP Diet and Health Study. Between 1995 and 1996, 461,682 adults aged 50 to 71 years completed a detailed food frequency questionnaire documenting their habitual eating patterns. The researchers used these responses to estimate each participant’s intake of ultra-processed foods and then followed the cohort through 2018, a median of 18.8 years, during which incident colorectal cancer cases were identified through linkage with cancer registries. This combination of scale and follow-up duration gives the analysis statistical power that few dietary studies can match, allowing the investigators to detect even modest associations between food groups and cancer risk.

The headline result was striking in its simplicity: when all ultra-processed foods were considered together, there was no association between total UPF intake and colorectal cancer incidence. Participants who ate the most UPF overall were not more likely to develop colorectal cancer than those who ate the least. This null finding stands in contrast to the monolithic framing that has dominated public discussion of ultra-processed foods, in which the category is often treated as a single, uniformly hazardous block of the food supply. The data suggest that this framing obscures more than it reveals, because the health consequences of a food depend on what the food actually is, not merely on how it was made.

When the researchers disaggregated the UPF category into its constituent food groups, the picture changed dramatically. Higher intake of whole grains, fiber, dairy products, and calcium derived from ultra-processed sources was associated with a lower incidence of colorectal cancer, while meat from ultra-processed sources was associated with a higher incidence. In other words, an ultra-processed whole grain bread and an ultra-processed sausage sit at opposite ends of the risk spectrum despite sharing the same processing label. The associations observed within these food groups were consistent with long-standing dietary guidance for colorectal cancer prevention, which emphasizes whole grains, fiber, dairy, and calcium while recommending limits on red and processed meat.

The team also performed a substitution analysis that offers a practical takeaway for readers. Replacing 10 percent of gram weight from ultra-processed food intake with minimally processed foods was associated with a 2 percent lower incidence of colorectal cancer. While the magnitude of this effect is modest, it reinforces the value of shifting the overall balance of the diet toward fresh and minimally processed options. The result also implies that the potential benefit of reducing UPF consumption lies less in avoiding the processing category as a whole and more in the specific nutritional substitutions that such a shift typically involves, such as trading processed meats for vegetables, legumes, and whole foods.

These findings arrive at a moment when ultra-processed foods have become one of the most hotly debated topics in nutrition science and public health policy. Several countries have considered front-of-package warnings or taxation schemes targeting the UPF category, and recent dietary guidelines in some nations have begun to explicitly recommend limiting ultra-processed foods regardless of their nutritional profile. The new study does not settle that policy debate, but it does provide a caution against treating the NOVA processing category as a proxy for healthfulness. A food’s position within the processing spectrum, the data suggest, is a far less reliable guide to colorectal cancer risk than the food’s actual composition, particularly its content of whole grains, fiber, dairy, calcium, and meat.

The researchers are careful to acknowledge the boundaries of their evidence. The study cohort consisted primarily of older, white Americans, and the findings cannot be generalized with confidence to younger, more diverse populations whose dietary patterns and cancer risk profiles may differ substantially. In addition, UPF intake was measured only once, at baseline in the mid-1990s, a period when ultra-processed foods were less ubiquitous in the American food supply than they are today. As eating habits changed and new UPF products became available over the following decades, the single baseline measurement may have underestimated participants’ actual long-term intake, potentially biasing the results in unpredictable directions. Future studies with repeated dietary assessments and more diverse cohorts will be needed to confirm whether the food-group pattern observed here holds in other populations and eras.

Loftfield summarized the implications in a statement accompanying the publication: in this large population of older U.S. adults, the team did not observe an association between total ultra-processed food intake and colorectal cancer incidence, but when the investigators examined food groups such as whole grains, dairy, and meat by their UPF or non-UPF source, the associations aligned with current dietary guidance for colorectal cancer prevention, such that higher whole grain and dairy intakes and lower meat intakes were associated with lower colorectal cancer incidence. The study, funded by the Intramural Research Program of the National Cancer Institute, with authors from the United States, France, the Netherlands, Brazil, and Australia, ultimately suggests that ultra-processed foods should not be treated as a monolith. For readers seeking to reduce their colorectal cancer risk, the message is refreshingly familiar: fill the plate with whole grains, fiber, dairy, and calcium, keep processed meat to a minimum, and let the food itself, rather than its processing label, guide the choice.

Subject of Research: Association between ultra-processed food intake and colorectal cancer incidence in the NIH-AARP Diet and Health Study cohort

Article Title: Total ultra-processed food intake not linked to colorectal cancer in large US cohort study

Article References: Total ultra-processed food intake not linked to colorectal cancer in large US cohort study. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: ultra-processed foods, colorectal cancer, NIH-AARP Diet and Health Study, PLOS Medicine, National Cancer Institute, dietary risk factors, whole grains, processed meat, NOVA classification, cohort study, nutrition epidemiology, cancer prevention