Second, the method of data collection relied on a single dietary "snapshot." Participants reported their eating habits only once, at the start of the study in the mid-1990s. The researchers were unable to account for how an individual’s diet might have changed over the following twenty years. Furthermore, the landscape of the American food system shifted dramatically between 1995 and 2018. The variety and availability of ultra-processed foods increased significantly during this window, meaning the initial assessments may have underestimated the actual lifetime consumption of these products by the participants.
Finally, the study was observational in nature. While it can identify correlations between certain foods and cancer rates, it cannot definitively prove a cause-and-effect relationship. Other lifestyle factors, such as physical activity, smoking, or underlying health conditions, could also play a role in the observed outcomes, although researchers attempt to control for these variables.
What the Results Mean for a Healthy Diet
The primary takeaway from this research is a call for nuance. Rather than treating all ultra-processed foods as an undifferentiated group of "bad" foods, the findings support a more granular evaluation based on nutritional content. The study suggests that the label "ultra-processed" is not a perfect proxy for "unhealthy," especially when the foods in question are rich in fiber or calcium.
Loftfield explained the significance of these distinctions in a statement accompanying the study: "In this large population of older US adults, we did not observe an association between total ultra-processed food (UPF) intake and colorectal cancer incidence; however, when we looked at food groups, like whole grains, dairy, and meat, by UPF or non-UPF source, we found that associations were in line with current dietary guidance for colorectal cancer prevention such that higher whole grain and dairy but lower meat intakes were associated with lower colorectal cancer incidence."
These results largely reinforce existing dietary guidelines. For years, health organizations have encouraged the public to increase their intake of whole grains and dairy while strictly limiting processed meats. This study confirms that these rules remain the most reliable markers for reducing colorectal cancer risk, regardless of whether the whole grains or dairy come in a package.
Ultimately, the research highlights that the "ultra-processed" designation may not tell the whole story of a food’s impact on long-term health. While the category remains a useful tool for identifying many low-nutrient, high-calorie foods, it is the specific nutritional profile—the presence of fiber and calcium versus the presence of processed meat compounds—that appears to be the true driver of colorectal cancer risk. For consumers, the message is clear: the ingredients and the type of food matter more than the factory it came from.
Research Funding and Disclosures
The study was supported and funded by the Intramural Research Program of the National Cancer Institute (NCI), part of the National Institutes of Health. Several of the study’s authors, including Loftfield, are current or former employees of the NCI. The funding organization provided the resources for the research but did not participate in the design of the study, the analysis of the data, or the final decision to publish the findings.
