For years, the term "ultra-processed food" (UPF) has served as a shorthand in nutritional science for dietary choices that may contribute to chronic illness. From sugary sodas to packaged snacks and ready-to-eat meals, these products have become a dominant force in the modern American diet, accounting for more than half of the total calories consumed by adults today. Given their prevalence, it is perhaps unsurprising that they have faced increasing scrutiny, with many researchers and public health advocates linking them to a host of health issues, including colorectal cancer (CRC).
However, a landmark study involving more than 460,000 Americans is now challenging the notion that all ultra-processed foods are created equal. Published on October 15 in the open-access journal PLOS Medicine, the research suggests that the "ultra-processed" label may be too blunt an instrument to accurately gauge the health risks of specific food items. Led by Erikka Loftfield of the National Cancer Institute, the study indicates that while the degree of industrial processing is a factor, the nutritional profile and specific ingredients within those foods play a far more significant role in determining cancer risk than the processing category alone.
A Massive Study Tracks Cancer Risk for Nearly Two Decades
To unravel the complex relationship between dietary habits and long-term health outcomes, researchers turned to the NIH-AARP Diet and Health Study. This massive, long-term endeavor provided a robust foundation for analysis, encompassing data from 461,682 American participants. When they enrolled in the study between 1995 and 1996, these individuals were between 50 and 71 years old, providing a unique look at how dietary patterns in middle and later life influence the development of cancer over time.
At the onset of the study, participants completed comprehensive questionnaires detailing their typical eating habits. By analyzing these responses, researchers were able to estimate each individual’s consumption of ultra-processed foods. The research team then tracked the participants through 2018, resulting in a median follow-up period of 18.8 years. This extensive duration allowed scientists to observe how the dietary choices made at the end of the 20th century correlated with the diagnosis of colorectal cancer over the subsequent two decades.
When the researchers looked at the data in the aggregate, the results were somewhat counterintuitive. They found no overall association between the total consumption of ultra-processed foods and the incidence of colorectal cancer. In other words, when participants were viewed as a broad group, those who consumed more ultra-processed foods were not significantly more likely to develop colorectal cancer than those who consumed less. This finding complicates the prevailing narrative that the level of processing is the sole, or even the primary, driver of cancer risk.
The Complexity of Food Categories: Nuance in Nutrition
While the study found no evidence of a simple "more processing equals more cancer" rule, a more granular examination of specific food categories revealed a much more complicated reality. The researchers discovered that the "ultra-processed" category is, in fact, an incredibly diverse group of products. It includes everything from nutrient-dense whole grain breads and calcium-fortified dairy products to processed meats and high-sugar snacks. When the team separated these foods into distinct categories, they found that certain types of ultra-processed foods were associated with higher cancer risks, while others appeared to have a protective effect.
Specifically, the study found that higher consumption of whole grains, fiber, dairy products, and calcium—even when these nutrients were obtained through ultra-processed sources—was associated with a lower incidence of colorectal cancer. This is a critical distinction, as it suggests that the nutritional benefits of these food groups persist regardless of the industrial processing methods used to create them.
Conversely, the data for meat products told a different story. Higher consumption of ultra-processed meat products was clearly linked to a higher incidence of colorectal cancer. This divergence illustrates the danger of using broad labels like "ultra-processed" to guide dietary choices. If researchers had simply categorized these items by their processing level, the protective benefits of certain grains and dairy products might have been obscured by the harmful effects of processed meats, or vice versa.
The research team also investigated the potential impact of dietary shifts. Their analysis suggested that replacing just 10% of one’s ultra-processed food intake with minimally processed alternatives could be associated with a 2% lower incidence of colorectal cancer. This finding reinforces the idea that while processing is a factor, the nutritional composition of what is on the plate remains the most vital consideration for cancer prevention.
Limitations and the Need for Context
Despite the scale of the study and the lengthy follow-up period, the researchers are careful to note that these findings come with important limitations. First and foremost, the study population was predominantly composed of older, white Americans. Because of this, the results may not be generalizable to younger adults or to more racially and ethnically diverse populations who may have different dietary habits and health risk factors.
Furthermore, the study relied on dietary information collected at a single point in time—the very beginning of the study. This creates a "snapshot" problem, as the researchers could not account for how the participants’ diets evolved over the subsequent 19 years. During that period, the food environment in the United States changed drastically, with a significant increase in the variety and availability of ultra-processed foods. Consequently, the initial assessment might have underestimated the actual lifetime consumption of these foods for many participants.
Additionally, because the study was observational in nature, it cannot definitively prove a cause-and-effect relationship. While the data shows a clear correlation between certain food types and cancer risk, it cannot isolate these variables from other lifestyle factors that might influence health outcomes.
Implications for a Healthier Future
Ultimately, the findings from this study serve as a necessary recalibration of how we think about the food we eat. Rather than viewing the "ultra-processed" label as a universal warning, the researchers suggest that consumers and policymakers alike should focus on the specific nutritional content of foods.
The results align well with existing, well-established dietary recommendations for colorectal cancer prevention, which consistently advise prioritizing whole grains, fiber, and calcium-rich dairy while limiting the intake of processed meats. The study does not give a "green light" to consume everything that is ultra-processed, but it does clarify that an item’s health profile is defined by its ingredients, not merely by the industrial machinery used in its production.
As Erikka Loftfield noted, in this large population of older U.S. adults, the researchers did not observe an association between total UPF intake and CRC incidence. However, by looking at specific food groups, they found that the associations were consistent with current dietary guidance. When we strip away the broad labels, the old adage about eating a balanced, nutrient-rich diet remains the most reliable strategy for health. The study ultimately highlights that when it comes to colorectal cancer, the specific nature of what people eat matters far more than the simple category of their processing.
The research was funded by the Intramural Research Program of the National Cancer Institute at the National Institutes of Health. The study authors, including members of the National Cancer Institute’s Intramural Research Program, were responsible for the study’s execution and analysis. The funding organization played no role in the study’s design, data collection, or the decision to publish the findings, ensuring the independence of the scientific results presented in PLOS Medicine.
