August 6, 2025

expert reaction to chips, other forms of potato and whole grains, and diabetes incidence

A study published in the BMJ looks at chips, potatoes and whole grains and type 2 diabetes risk.

Dr Ruth Boocock, dietitian and Associate Professor (Knowledge Exchange), Teeside University, said:

“This study adds to the body of evidence that eating whole grain foods such as granary bread, brown rice and wholewheat pasta instead of more processed carbohydrates foods like french fries is beneficial for health, potentially reducing our risk of type 2 diabetes, but cannot prove cause.

“Promoting lower fat preparation methods also aligns with current dietary advice.

“The data collection method used in this study makes it difficult to accurately assess the impact of the amount of carbohydrate foods eaten, which is also a significant factor in type 2 diabetes risk.”

Comments from our colleagues at the Spanish SMC:

Diana A. Díaz Rizzolo, Lecturer at the Open University of Catalonia (UOC), member of the UOC’s NUTRALiSS Nutrition, Food, Health and Sustainability Research Group, and coordinator of the Spanish Diabetes Society’s Lifestyle Working Group, said:

“This is a powerful study that uses data from three large US cohorts, which gives it a lot of robustness.  Although it is observational, it is well designed and adjusted for multiple factors, so even though it cannot prove causality due to the nature of the study, its results allow us to consider it a reasonable possibility.  Why?  Because it addresses a key point that many nutritional epidemiological studies tend to overlook, and this is where bias usually lies: it accurately analyses what foods are consumed when French fries are not consumed.

“This is key, because in nutrition it is not only what we eat that matters, but also what we stop eating when we do so.  The replacement food can completely change the impact of a dietary decision, and this overall dietary pattern often has a greater impact on overall health than the contribution of a specific food.

“Yes, there is a 20% increase in relative (not absolute) risk when eating chips, but this is not observed for other types of cooking, reinforcing the idea that we should not demonise whole foods without considering how they are prepared, what they are accompanied by or what they are replaced with.  In fact, the study shows that replacing them with whole grains can be beneficial, while replacing them with white rice can be even worse for our glycaemic profile, which is actually quite in line with current guidelines.”

Cristóbal Morales, Specialist in Endocrinology and Nutrition, Vithas Sevilla Hospital, said:

“The study is rigorous and well designed.  Although it cannot prove causality, it provides valuable and already known evidence that supports current recommendations to prioritize whole grains and limit fried foods, even when it comes to options that may initially seem “healthy” such as potatoes.  A clear message: preventing type 2 diabetes starts with adopting and maintaining healthy lifestyles and nutrition.”

‘Total and specific potato intake and risk of type 2 diabetes: results from three US cohort studies and a substitution meta-analysis of prospective cohorts’ by Seyed Mohammad Mousavi et al. was published in the BMJ at 23:30 UK time on Wednesday 6 August 2025.

DOI: 10.1136/bmj-2024-082121

Declared interests

Dr Ruth Boocock: “UK registered dietitian (clinical specialty diabetes, 25 years in NHS)

Current Diabetes UK Clinical Champion 2024-5. 

Published author (doctorate focused on type 2 diabetes remission strategies).”

Diana A. Díaz Rizzolo: “She declares that she has no conflicts of interest.”

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