UEx researchers study the health effects of consuming ultra-processed tofu and seitan

Tofu and seitan are a variety of plant-based products widely present in the culinary traditions of Asian countries, where they are consumed as part of a varied diet alongside meat, fish, or seafood. On the other hand, in Western countries, these products are frequently identified as meat analogues or meat substitutes and are chosen by consumers for reasons of animal welfare, environmental impact, or health.

However, as Mario Estévez García , professor of Food Technology at the University of Extremadura , warns, "these foods sold in Spain are prepared very differently from the originals we find in Asian countries, for example, tofu, which is a fermented food with many health benefits. Here we have seen that both tofu and seitan from the main supermarkets fall into the ultra-processed category."

The study, conducted by researchers from the TECAL group at the University Institute of Meat and Meat Products (IProCar), analyzed the digestion of these foods compared to meat, with the aim of determining their impact on health. The research was conducted on animal models, specifically Wistar rats, and is part of a broader research project that includes various tests in humans and animals.

The results show that the consumption of tofu and seitan leads to significant adverse effects, such as inflammation and intestinal dysbiosis, in addition to being nutritionally different from meat. "We gave the animals a feed enriched with red meat, another feed that was modified to include the same amount of calories and protein from seitan, and another with tofu. The digestion process observed was completely different for the three types," says researcher Mario Estévez.

Meat protein is highly digestible, which determines how much of the protein is digested and how many of its amino acids pass into the bloodstream and can therefore be utilized by the body. The results show that approximately 50 percent of meat protein is digested slowly in the stomach, which increases the feeling of satiety, and approximately 30 percent in the small intestine. "Satiety is an important factor as it determines the amount of food we eat and how long it takes to regain satiety," explains the researcher.

[img src="https://comunicacion.unex.es/wp-content/uploads/sites/70/2025/03/horizontal-mario-591x449.jpg" alt="" width="430" height="327">On the other hand, the digestion process of ultra-processed tofu and seitan was analyzed, and both were found to have poor digestibility. This means that the body is unable to digest the protein in these foods as efficiently as meat protein. Furthermore, in the case of seitan, which is made from wheat gluten and leads to an adverse response in celiac patients, the study also observed an inflammatory process in healthy individuals, both animals and humans.

“It's worth noting that, although none of the people in the study had been diagnosed with celiac disease, all had elevated levels of the inflammatory marker interleukin 6 , an indicator of inflammatory processes associated with the consumption of certain foods. This is medically relevant because these are asymptomatic inflammatory processes that become chronic over time, as there's no reason to suggest we shouldn't eat those foods.”

In the case of commercial tofu, the soy protein undergoes such severe industrial modification that it cannot be digested in either the stomach or the small intestine, triggering a fermentation process in the large intestine that induces dysbiosis , or an imbalance in the microbiota. Furthermore, this fermentation releases a series of toxic substances or metabolites described in the scientific literature as carcinogenic, for example, p-cresol.

"Beyond the loss of nutritional value that comes with not being able to properly digest a protein, it also generates a series of intestinal disorders and substances that are very harmful to health."

The results of this study support the WHO's statement on the risks of consuming so-called meat analogues: New WHO factsheet: How can we tell if plant-based products are healthy? "More studies are needed to provide scientific evidence on these foods and their long-term effects," the researcher concludes.

Literature:

Sánchez‐Terrón, G., Martínez, R., Freire, MJ, Molina‐Infante, J., & Estévez, M. (2024). Gastrointestinal fate of proteins from commercial plant–based meat analogs: Silent passage through the stomach, oxidative stress in intestine, and gut dysbiosis in Wistar rats. Journal of Food Science , 89 (12), 10294-10316.

https://doi.org/10.1111/1750-3841.17458

Source: Scientific Culture Dissemination Service