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New research out of Finland is challenging the concept that all processed plant-based foods are unhealthy.
The groundbreaking study reveals that food processing methods greatly affect the health value of plant-based foods. But contrary to popular opinion, these methods could actually have a positive impact, by enhancing beneficial compounds.
Positive impacts of plant-based processingPlant-based foods, including vegan burgers and tempeh, undergo varying levels of processing during the production. These processes can enhance nutritional content through fortification and improve sensory qualities like texture.
However, processing of food and beverage products, particularly within the plant-based category, has become associated with negative health impacts.
A new study, conducted by the Food Sciences unit at the University of Turku in Finland, has found that different processing methods have a significant impact on the biochemical composition of plant-based foods.
Researchers analysed commercially available plant-based products, such as foods made from soy, peas, wheat, and fava beans. Using a non-targeted metabolomics analysis, they discovered that different processing methods have significant effects on the biochemical composition of the products.
“Plants and plant-based products are known to contain phytochemicals, which are bioactive compounds that can have health benefits,” says Kati Hanhineva, professor of food development at the University of Turku. “Until now there has not been enough research on how different processing methods affect these compounds.”
The team found fermentation to be an important processing method in the results, as it actively enhances the nutritional value of a product. Tempeh, in particular, contains isoflavonoids in a form that is more readily absorbed due to the activity of the microbes used in the fermentation process.
Tempeh contains isoflavonoids in a form that is more readily absorbed due to the activity of the microbes used in the fermentation process. (danikancil/Image: Getty/danikancil)NOVA classification failingsThe heavily-criticised NOVA classification system, which currently defines processing levels, was again found wanting by the researchers.
Under NOVA, the fermented products tested fell into the ultra-processed category, which is associated with negative health outcomes. The products made with extrusion also fell into the UPF category, despite the fact they contained high levels of isoflavonoids. This, say the researchers, highlights how the current classification system fails to recognise healthiness of plant-based products.
“Processing food is common, and even unprocessed food is often eventually processed at home, for example by cooking,” says Ville Koistinen, research fellow at the University of Turku.
The NOVA classification primarily takes into account the processing technique used for the product and the type and number of added ingredients, rather than its biochemical composition.
“It cannot be assumed that all processing makes a product unhealthy, because ultimately it is only the nutritional components of the edible product that matter, and how they are absorbed by our bodies. These determine the nutritional value and healthiness of food products,” adds Koistinen.
NOVA classification fails to recognise the health benefits of plant-based foods. (Image: Getty/AleksandarGeorgiev)Backlash against the plant-based backlashUnder NOVA, ultra-processed plant-based foods are classified as ‘unhealthy’ and increasingly avoided by concerned consumers. This is a widely-held belief the researchers are looking to dispel.
“It is important to note that food processing should not be seen as exclusively harmful, as fermentation, for example, can even improve the nutritional value of a product,” says Jasmin Raita, doctoral researcher at the University of Turku.
The researchers suggest that future food classification systems should be developed to take into account the effects of processing on the biochemical composition of products. They propose any new classification should recognise the loss of useful compounds in the process and the formation of new ones, as well as the value of the added ingredients to the product, not just the addition of harmful ingredients such as salt. For example, many spices are rich in compounds with health benefits.
“Highly processed plant-based protein-rich foods have been on the market for such a short time that it is too early to say anything for certain about the healthiness of all processed plant-based products as a whole, but research on this topic is active,” says Hanhineva. “What is known, however, is that in population-based epidemiological studies, all food groups rich in phytochemicals are healthy, while unhealthy food categories typically do not contain them. Therefore, it is justified that the range of phytochemicals should be better recognised in the categorisation of foods.”
Source: Existing food processing classifications overlook the phytochemical composition of processed plant-based protein-rich foods
Published online: 24 March 2025
DOI: 10.1038/s43016-025-01148-5
Authors: Jasmin Raita, Hany Ahmed, Kang Chen etc.
