A fall 2022 study by Chalmer’s University of Technology in Sweden has shown evidence that the nutrients from some plant-based meat alternatives may be more difficult for the human body to digest compared with their livestock-sourced counterparts.
What nutrients, you may ask? Well, the foods studied in the supermarkets were Swedish. In total, 44 meat substitutes made primarily of soy and pea proteins were analyzed for dietary contents such as fiber, fat, zinc, iron, phytate, salt, phenolics, and protein, as well as other amino acids and fatty acid composition.
»Related: Report zeros in on plant-based product use throughout the U.S.
“This study shows difficulties obtaining essential minerals from a diet in which meat has been replaced with products based on legume or cereal proteins, which might lead to an increase in iron deficiency, especially among vulnerable groups,” the authors wrote.
Phytates or phytic acid is the primary storage form of phosphorous in many plant tissues, but especially in beans and cereal grains. According to the study, phytates accumulate when proteins are extracted for meat substitutes, forming insoluble compounds with dietary minerals in the digestive tract. While the majority of the products examined were high in zinc and iron, there was overall, a wide variation of nutritional content and nutrients were low in bioavailability primarily due to phytate presence with one exception: tempeh.
Tempeh is a traditional Indonesian food made from fermented soybeans formed into a block. According to the study, the fermentation process that tempeh undergoes reduces phytate content significantly. The fermentation process for tempeh utilizes Rhizopus oligosporus. R. oligosporus, a fungus with the ability to produce a phytate-degrading enzyme, phytase.
“The use of refined meat substitutes is becoming increasingly common, with the main reason for choosing plant-based meat substitutes associations of it being ‘better for you’ and ‘better for the planet.’ Previous work points out that many novel meat substitutes have high contents of salt and saturated fat showed that iron content is an important criteria for consumers when choosing meat alternatives, and that there is an expectation that the availability of iron in meat substitutes is comparable to that of red meat,” reads the study.
The research was published in the journal Nutrients, a peer-reviewed, open access journal of human nutrition.
Although some of the products studied were fortified with iron, researchers conclude that the bioavailability of added iron is still inhibited by phytates. Meanwhile, animal protein products contain the “meat factor,” which stimulates the absorption of nonheme iron in the whole meal as well as zinc absorption.
The study reads in conclusion, “Our results call for a sharpening on the interpretation of nutrition claims, especially for iron, which would create incentive for producers to improve their products with regard to iron bioavailability.”
Ann-Sofie Sandberg, co-author of the study, suggested that enzymes of microorganisms might be useful tools in breaking down phytates as well as the use of fermentation. Researchers also suggested focusing on mineral bioavailability and adding high-quality fat while decreasing salt in future products.
