Patrick Rühs, are processed foods unhealthy?
Industrial food processing is often the target of criticism – unjust criticism, says Patrick Rühs, as many processing steps actually make foods healthier and easier to digest.?
Food processing takes many forms, and most foods are processed in one way or another – by grinding, pasteurisation or fermentation. People don’t want to eat unprocessed wheat – they want to eat bread. Moreover, bread, yoghurt, cheese, and cured sausages such as salami are all fermented using fungal or bacterial cultures. Fermentation is one of the oldest food processing techniques and makes foods less perishable, easier to digest and more aromatic. Sourdough bread is considered particularly healthy, as micronutrients are more readily available to the body thanks to fermentation with lactic acid bacteria.
In other words, processing does not make foods unhealthy. Rather, it makes them easier to digest and, in many cases, healthier. What’s more, processing is essential for some foods to make them safe and non-perishable. Cases of illness or death occur time and again because of people drinking raw milk, for example.
The expert
Patrick Rühs is Professor of Food Structure Engineering at the Department of Health Sciences and Technology of ETH Zurich.
Nevertheless, many people unfortunately believe that the more food has been processed, the unhealthier it is. In this context, the media often cite a 2019 study by scientists from France and Brazil,1 in which the researchers investigated the risk of cardiovascular diseases and suggested that all processing steps are unhealthy.
However, many experts in food and nutrition science criticise this study for several reasons – one of them being that the authors’ classification of the food was, in part, unclear and inconsistent. For example, the study classifies bread that was identical from a nutritional perspective as highly processed if it was produced industrially but as minimally processed if it was baked at home. Moreover, many processed products were lumped into the same category as sugar sweetened drinks, which are well known to be unhealthy. This is one key reason why processed products fare poorly in the study.
In any case, scientifically sound studies have failed to substantiate a negative relationship between the degree of processing and the healthiness of a food. I and many other food scientists reject the term “ultra-processed foods” because it suggests such a relationship and creates misplaced dietary incentives.
It is not processing, that makes food unhealthy. Likewise, one has to be careful with the widespread assumption in society that the more additives a product contains, the unhealthier it is. Butter, for example, contains no additives at all but is not healthy. Conversely, baby food – an industrial product with lots of vital additives – is essential to the health of many infants.
Food Day 2025
Processed foods will also be a key topic at Food Day, taking place on 29 October 2025 at ETH Zurich under the motto “Planting Healthier Nutrition”. Experts from the fields of science, practice and politics will discuss how agriculture, the food industry and research can collaborate to find ways to create healthier and more sustainable food systems. The event is aimed at professionals and anyone interested in the future of our food.
Further information and registration details can be found on the Food Day 2025 website
Whether a diet is healthy depends primarily on the nutrients it contains and whether these can be absorbed by the body. The quantity, variety and quality of the food eaten are also important factors.
Not only is food processing important, but it also has a promising future. Indeed, it plays a vital role – particularly in the case of plant-based foods.2 In food science, we are currently conducting intensive research into how we can make greater use of fermentation – using fungal cultures, for example – in order to convert legumes into digestible foodstuffs with readily available nutrients.
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References
1 Srour B, Fezeu LK, Kesse-Guyot E, Allès B, Méjean C, Andrianasolo RM, Chazelas E, Deschasaux M, Hercberg S, Galan P, Monteiro CA, Julia C, Touvier M: Ultra-processed food intake and risk of cardiovascular disease: prospective cohort study (NutriNet-Santé). BMJ 2019, doi: external page 10.1136/bmj.l1451
2 Germerdonk T, Bach A, Marangoni AG, Mishra K, Rühs PA: Unrefined plant raw materials are key to nutritious food, Nature Food 2025, doi: external page 10.1038/s43016-025-01195-y