Low nutritional quality in many vegetarian meat substitutes
The availability of foods based on plant proteins to substitute for meat has increased dramatically as more people choose a plant-based diet. At the same time, there are many challenges regarding the nutritional value of these products. A study from Chalmers University of Technology in Sweden now shows that many of the meat substitutes sold in Sweden claim a high content of iron — but in a form that cannot be absorbed by the body.
A diet largely made up of plant-based foods such as root vegetables, pulses, fruit and vegetables generally has a low climate impact and is also associated with health benefits such as a reduced risk of age-related diabetes and cardiovascular disease, as has been shown in several large studies. But there have been far fewer studies of how people’s health is affected by eating products based on what are known as textured* plant proteins.
In the new study from Chalmers, a research team in the Division of Food and Nutrition Science analysed 44 different meat substitutes sold in Sweden. The products are mainly manufactured from soy and pea protein, but also include the fermented soy product tempeh and mycoproteins, that is, proteins from fungi.
‘Among these products, we saw a wide variation in nutritional content and how sustainable they can be from a health perspective. In general, the estimated absorption of iron and zinc from the products was extremely low. This is because these meat substitutes contained high levels of phytates, antinutrients that inhibit the absorption of minerals in the body,’ says Cecilia Mayer Labba, the study’s lead author, who recently defended her thesis on the nutritional limitations of switching from animal protein to plant-based protein.
The body misses out on necessary minerals
Phytates are found naturally in beans and cereals — they accumulate when proteins are extracted for use in meat substitutes. In the gastrointestinal tract, where mineral absorption takes place, phytates form insoluble compounds with essential dietary minerals, especially non-heme iron (iron found in plant foods) and zinc, which means that they cannot be absorbed in the intestine.
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