November 13, 2025

expert reaction to study on the association between ultra-processed food (UPF) intake and bowel polyps in women under 50 in the US, as published in JAMA Oncology

Scientists comment on study on the association between ultra-processed food (UPF) intake and bowel polyps in women under 50 in the US, as published in JAMA Oncology

Prof Marco Gerlinger, Professor of Gastrointestinal Cancer Medicine and Consultant Medical Oncologist, Barts Cancer Institute, St Bartholomew’s Hospital, said:

Does the press release accurately reflect the science?

“Yes, the press release is an accurate summary.”

Is this good quality research?  Are the conclusions backed up by solid data?

“Bowel cancer diagnoses are on the rise in individuals under the age of 50 and we still have no idea why this is happening. This study indicates that high ultra-processed food consumption is associated with a higher risk of developing bowel polyps under the age of 50. Bowel cancer often arises from polyps and the results from this high-quality study in over 20,000 individuals provide a plausible explanation, that ultra-processed food consumption may play a central role in early onset bowel cancer. However, this study is purely an association of highly processed food consumption with bowel polyp diagnoses which are precursors to bowel cancer, and as such cannot prove causation i.e. that UPF are causing the development of these polyps, and so more research is needed to understand a potential mechanism related to this association. The study is also retrospective in nature, and it could miss other environmental exposures or lifestyle factors that contribute to early polyp development.”   

How does this work fit with the existing evidence?

“The association between ultra-processed food consumption and higher bowel cancer risk is already know. What is new is that it is also associated to early onset bowel polyps in the age group where we see the biggest rise in new bowel cancer diagnoses.”

Have the authors accounted for confounders?  Are there important limitations to be aware of?

“Confounders such as other lifestyle factors including smoking or physical activity and comorbidities have been considered. The main limitation is the retrospective nature of the analysis. Confirmatory studies are clearly needed to substantiate the findings and to assess if highly processed food consumption actually leads to increased bowel cancer diagnoses in patients under the age of 50.” 

What are the implications in the real world?  Is there any overspeculation?

“The study adds to the long list of health problems that have been associated with highly processed food consumption. Although we need more data and it is too early to recommend avoiding UPFs, having a good look at your diet and trying to reduce UPF consumption makes sense.”

Does the associated risk increase based on number of units of UPF consumed?

“The associated risk of developing polyps increased rather constantly with higher UPF consumption. So, there is no cutoff below which consuming UPFs were associated with no effect, according to the data. On the flip side, any reduction in UPF intake was associated with a decrease in polyp risk.”

Prof Gunter Kuhnle, Professor of Nutrition and Food Science, University of Reading, said:

“In order to investigate the effects of ultra-processed food intake on health, it is important to be able to measure how much ultra-processed food people consume. This is very difficult – even with very detailed dietary information – because the definition is ambiguous and most methods don’t collect enough information. Study participants might record “bread” – but it is impossible to know whether it is ultra-processed or not.

“This study relies on food-frequency questionnaires to estimate ultra-processed food intake: by their very nature, they need to combine different foods and collect less information. Many foods that are listed as options have ultra-processed and non-ultra-processed options (e.g. tomato sauce, bread or breakfast cereals) and it is impossible for the scientist to know what has actually been consumed. A participant consuming porridge, home-sourdough bread and home-made tomato sauce will tick the self-same boxes as someone eating coco pops, industrially made bread and tinned tomato sauce – but only one of them will have consumed ultra-processed foods.

“Having unreliable data on UPF intake makes it very difficult to investigate links with disease – if we don’t know what someone has consumed, investigating associations with diet is difficult. The results therefore do not necessarily reflect associations between ultra-processed food intake and disease risk, but rather the association for specific food groups.”

‘Ultra-Processed Food Consumption and Risk of Early-Onset Colorectal Cancer Precursors among Women’ by Chen Wang et al. was published in JAMA Oncology at 16:00 UK time on Thursday 13 November 2025

DOI: doi:10.1001/jamaoncol.2025.4777

Declared interests:

Prof Gunter Kuhnle: Current funding: BBSRC Research Funding (Transforming UK Food System)

Other collaborations: Ongoing research collaboration with Mars on health effects of flavan-3-ol

For all other experts, no reply to our request for DOIs was received.