16 October 2026 (Navroze Bureau) Replacing just 10% of ultra-processed foods with minimally processed alternatives may be associated with a lower incidence of bowel cancer, according to a new study published in PLOS Medicine on October 15, 2026. Researchers analysing dietary data from more than 460,000 adults in the United States found that replacing 10% of ultra-processed food intake, by weight, with an equivalent amount of minimally processed food was associated with a 2% lower incidence of colorectal cancer.
The findings offer a more detailed picture of the relationship between food processing and bowel cancer. The researchers found no overall association between total ultra-processed food intake and bowel cancer incidence in their main analysis. Instead, the results varied according to the types of foods people consumed, suggesting that nutritional content and food category may matter alongside the degree of processing.
Bowel cancer, also known as colorectal cancer, affects the colon or rectum. Diet is one of several factors that can influence risk, alongside age, family history, physical activity, smoking, alcohol consumption and other health-related factors. The new research adds to evidence examining whether replacing certain foods with less processed alternatives may help support long-term health.
What did the study find?
The study examined 461,682 adults who were between 50 and 71 years old and did not have cancer when they entered the NIH-AARP Diet and Health Study in 1995–96. Researchers assessed participants’ dietary habits and followed cancer diagnoses for more than 20 years. During the follow-up period, more than 10,000 bowel cancer cases were recorded.
The analysis found that replacing 10% of ultra-processed food intake with the same weight of minimally processed foods was associated with a 2% reduction in bowel cancer incidence. However, the researchers did not find that consuming more ultra-processed food overall was consistently associated with a higher incidence of bowel cancer in this particular study.
The researchers also identified differences between food categories. Ultra-processed meat products, including reconstituted meats such as hot dogs, were associated with higher bowel cancer incidence. In contrast, certain foods containing whole grains, fibre, dairy and calcium were associated with lower incidence, even when those foods met the study’s definition of ultra-processed foods.
What counts as ultra-processed food?
Ultra-processed foods are generally industrially manufactured products containing ingredients or additives not typically used in ordinary home cooking. Examples include packaged snacks, sugary soft drinks, instant noodles, some ready-to-eat meals and processed meat products.
However, the category is broad. Some packaged breads and breakfast cereals provide whole grains and fibre, while other products may contain substantial amounts of salt, added sugar or saturated fat. Flavoured yoghurts, for example, can differ considerably in their sugar content and nutritional value.
The researchers cautioned that classifying every ultra-processed food as equally harmful may overlook these differences. Their findings suggest that the particular foods consumed, their nutritional composition and what they replace in a person’s diet are important considerations.
Why replacing foods may matter
Replacing some packaged snacks and processed meat products with fruits, vegetables, legumes and whole grains can improve the overall nutritional quality of a diet. These foods can provide fibre, vitamins and minerals that support digestive health.
For people looking to make practical changes, options include choosing fresh fruit instead of packaged sweet snacks, adding beans or lentils to meals, selecting whole-grain foods where available and limiting processed meats such as sausages and hot dogs.
The study does not mean that changing 10% of a person’s diet will guarantee protection against cancer. Its findings describe an association observed across a large population, not proof that the dietary substitution directly caused the reduction. The research also involved older US adults, so its results may not translate exactly to every age group or population.
What the findings mean for bowel cancer prevention
The results highlight the importance of looking beyond a single food label when evaluating dietary health. While replacing some ultra-processed foods with minimally processed alternatives was associated with lower bowel cancer incidence, the study did not establish that all ultra-processed foods increase risk.
The findings are consistent with general dietary advice to eat plenty of fibre-rich foods, including fruits, vegetables and whole grains, and to limit red and processed meat. Maintaining physical activity, limiting alcohol and avoiding smoking are also relevant to reducing cancer risk.
Researchers say further studies are needed to better understand how different food types and processing methods relate to cancer development. For now, the practical message is to focus on a balanced diet and make gradual substitutions that improve nutritional quality rather than assuming every packaged food has the same health effects.