Key Findings:
- A major new study involving nearly half a million participants has found no significant association between overall ultra-processed food consumption and colorectal cancer risk.
- Experts warn this does not mean all ultra-processed foods are safe.
- Processed meats remain linked to a higher cancer risk.
Whole grains, fibre, and dairy appear protective even when consumed in ultra-processed forms.
What the Study Found
Published in PLOS Medicine, the research tracked diet and health data from nearly 500,000 middle-aged and older American adults over more than two decades. Researchers calculated participants’ ultra-processed food intake using the NOVA classification system and analysed its relationship with colorectal cancer diagnoses.
The results were surprising: People with the highest ultra-processed food intake did not have a significantly higher risk of colorectal cancer compared to those with the lowest intake. Researchers suggest this is because ultra-processed foods form a highly heterogeneous category one that includes processed meats and sugary drinks alongside wholemeal bread, high-fibre breakfast cereals, and flavoured yoghurt.
The Details Matter
When researchers broke the category down into “subgroups”, sharply contrasting patterns emerged. “Processed meat” consumption was linked to increased colorectal cancer risk. Meanwhile, whole grains, dietary fibre, dairy, and calcium, even when delivered through ultra-processed foods, remained associated with reduced risk.
“This adds to the evidence that ultra-processed foods should not be treated as one single, uniform category,” said Rosiered Brownson-Smith, a researcher at King’s College London.
What Experts Say
Professor Jules Griffin, director of the Rowett Institute at the University of Aberdeen, described the study as “well conducted” but urged caution in interpreting it. “The US is one of the highest consumers of ultra-processed foods, accounting for 36% to 50% of total energy intake,” he said. “Within ultra-processed foods, whole grain consumption is relatively high and these foods are associated with reduced colorectal cancer risk.”
Several limitations deserve attention. Dietary data came from a single questionnaire administered in the mid-1990s, meaning it could not capture changes in food formulation over time or isolate the effects of specific additives. The participants were predominantly middle-aged and older white adults, so the findings do not apply to younger populations a particular concern given that early-onset colorectal cancer rates are rising globally.
Brownson-Smith stressed the bottom line: “The null result for total ultra-processed food intake does not prove that ultra-processed foods are harmless.”
