Ultra-Processed Food Not Linked to Colorectal Cancer in Huge US Study, but Processed Meat Still Raises Risk

NEW YORK — Eating more ultra-processed food was not linked to a higher risk of colorectal cancer in a large U.S. study of older adults, researchers reported Thursday, a finding that challenges assumptions about the category of foods and raises new questions about what is driving rising cancer rates among younger people.

The study, led by researchers at the National Cancer Institute and published in the journal PLOS Medicine, analyzed data from more than 460,000 adults who took part in the NIH-AARP Diet and Health Study.

Participants were followed for a median of nearly 19 years, with some tracked for as long as 23 years.

"We did not observe an association between total ultra-processed food (UPF) intake and colorectal cancer incidence," said Erikka Loftfield, a former National Cancer Institute investigator involved in the research.

Not all processed foods are equal

While overall consumption of ultra-processed foods was not tied to colorectal cancer, the researchers found that specific types of food told a different story.

When they examined food groups such as whole grains, dairy and meat, whether ultra-processed or not, the associations aligned with existing dietary guidance for preventing colorectal cancer. Higher intakes of whole grains and dairy, and lower intakes of meat, were linked to a lower incidence of colorectal cancer.

The researchers concluded that the nutritional content of foods may matter more than how heavily they are processed.

The findings suggest that grouping all ultra-processed foods together may obscure important differences. The category includes a wide range of products, from whole-grain breads and yogurts to sugary drinks, packaged snacks and processed meats.

Processed meat remains a concern

The connection between processed meats and colorectal cancer is well established. Products such as bacon, sausage, hot dogs and pepperoni have long been linked to a higher risk of the disease, and the World Health Organization classifies processed meat as a cancer-causing agent.

Experts say the new study does not change that guidance. Instead, it suggests that some ultra-processed foods, such as fortified whole-grain cereals or certain dairy products, may not carry the same risks as others.

Mixed evidence

Earlier research on ultra-processed foods and colorectal cancer has produced mixed results.

A 2022 study of more than 200,000 U.S. health care workers found that men who consumed the most ultra-processed food, more than nine servings a day on average, had a 29% higher risk of colorectal cancer than men who ate about three daily servings. That study did not find a similar link in women.

A 2025 study reported that ultra-processed foods may increase the risk of colorectal polyps, which can develop into cancer, in women under 50.

The new study did not extend those findings to total ultra-processed food intake across its large population of older adults.

Questions about rising cancer rates

The results come amid growing concern about the rising incidence of colorectal cancer among younger adults. While rates have declined among people 65 and older, they have increased among adults under 50, and scientists are still working to understand why.

Researchers have pointed to a range of possible factors, including obesity, diabetes, physical inactivity, changes in gut bacteria and diet. Ultra-processed foods have been among the suspected contributors.

The new findings raise questions about what role, if any, these foods play in the trend. However, because the study focused on older adults, it may not capture risks that affect people who began eating large amounts of ultra-processed foods earlier in life.

Limitations

The study relied on participants' reports of what they ate, which can be imprecise. Participants enrolled in the mid-1990s, when they were in their 50s to early 70s, and the food landscape has changed considerably since then.

The study was observational, meaning it can identify associations but cannot prove cause and effect.

What it means for consumers

Experts say the findings reinforce longstanding dietary advice rather than overturning it. Eating more whole grains, fiber, fruits and vegetables, consuming dairy and limiting red and processed meat remain key recommendations for reducing colorectal cancer risk.

The study also suggests that consumers may not need to avoid every food labeled ultra-processed, but should pay attention to the nutritional quality of what they eat.

Other well-established ways to lower colorectal cancer risk include maintaining a healthy weight, staying physically active, avoiding tobacco, limiting alcohol and getting recommended screenings. In the United States, screening is recommended beginning at age 45 for people at average risk.

Scientists say more research is needed to understand how specific ultra-processed foods affect cancer risk, particularly among younger people, and which ingredients or processing methods may be harmful.

Debate over ultra-processed foods is likely to continue, as researchers and policymakers weigh how best to define and regulate a category that includes both nutritious and less healthy products.