November 27, 2023

expert reaction to new research suggesting that taste perception of ultra-processed foods is no better than less processed foods

A study published in Appetite looks at taste perception of ultra-processed foods.

Dr Thomas A B Sanders, King’s College London, said: 

“This study in 224 adults compares the perceived liking and food reward of ultraprocessed foods compared with less processed or unprocessed food in randomized controlled trial. The study failed to demonstrate any evidence to suggest that ultraprocessed foods were perceived as more palatable by adults. The major weakness is that the judgements made by the participants were virtual (on-line) where they were asked to rank pictures of specific foods.  Food choice in the real world is influenced by packaging, placement of the product at point of sale, as well smell, taste and social context. Furthermore, the findings of this study cannot be generalised to children”. 

Dr Frankie Phillips, British Dietetic Association, said:

How meaningful is their challenge to the assumption that UPFs are ‘hyperpalatable’ considering the method involves being shown food rather than eating it?

“Looking at food is never going to replace the holistic impacts of actually eating foods – essentially only one of the senses is being used, sight, rather than taste, smell and mouthfeel. It is extremely theoretical.”

Is this study valuable to understand how we make judgements about foods?

“The information provided to participants is severely limited. Further research to find out how this relates to foods subsequently being eaten would be a valuable next step.”

Does the press release accurately reflect the science?

“Yes, again, theoretically liking for a food image might translate into actually eating the food. However, this study takes away the important part played by taste and other senses. Since taste is such a huge factor in food choice, it is limited to just the notional liking of the food.”

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

“It is a small theoretical study that hypothesises how food is liked and provides some useful insight into why certain foods are chosen.”

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

“With such interest in hyper processed foods it is of great interest to see if there is anything intrinsic to such foods that makes them more appealing and subject to over consumption. It also suggests that there may be a role for adapting the energy density of foods – for example by adding fibre to the food in some way to reduce energy density – and potentially improving the nutrient content of the food. The UK diet is still far too low in fibre, whilst it is higher in fat and salt than many years of recommendations have suggested.”

Dr Duane Mellor, Registered Dietitian and Senior Lecturer, Aston University, said:

“This is an interesting study, which was undertaken during a period impacted by COVID, meaning it could not physically assess how palatable or desirable foods were, instead it used pictures and an online survey. This means that all measures of food desirability were based on perceptions of the food rather than actually eating them. Therefore, it is unable to assess the suggestion that ultra-processed foods are more palatable than less processed foods, especially unlike a previous study in the US which showed ultra-processed food, matched for nutrients to less processed foods resulted in greater consumption and calorie intake.

“So, although this study showed that images of ultra-processed foods were not more desirable than less processed foods, this did not look at how much of these foods would have been eaten by the participants had they been given the opportunity. Therefore, any claims that this study is able to “challenge the assumption that ultra-processed foods are ‘hyperpalatable’” as stated by study’s lead author, is very hard to justify. As there is not a direct link between the liking or desiring of a food in a picture and actually finding it highly palatable when eating it. This is because simply seeing a food is only one part of how much food will be chosen and then eaten, as other factors such as its flavour, sensation, and the biological changes in our bodies (such as hormonal and glucose changes) which result from the act of eating a food, all combine to influence how palatable and how much food is ultimately consumed. 

“It is important that we do not use research based on looking at pictures of food to assess how tasty, palatable or ultimately its effect on our health.”

‘Evidence that carbohydrate-to-fat ratio and taste, but not energy density or NOVA level of processing, are determinants of food liking and food reward’ by Peter J. Rogers et al. was published in Appetite at 00:01 UK time on Monday 27^th November.

DOI: 10.1016/j.appet.2023.107124

Declared interests

Dr Duane Mellor has worked with a number of food companies giving technical and nutritional advice in the past.

Dr Thomas Sanders is a member of Science Committee British Nutrition Foundation, and Honorary Nutritional Director of Heart UK.