Low nutritional quality in vegan meat big problem

There are many challenges regarding the nutritional value of meat substitutes. A study from Chalmers 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 generally has a low climate impact and is also associated with health benefits, 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. 

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. 

‘We believe that making nutrition claims on only those nutrients that can be absorbed by the body could create incentives for the industry to improve those products,’ says Ann-Sofie Sandberg, Professor of Food and Nutrition Science at Chalmers and co-author of the study.

The food industry needs new methods

Tempeh, made from fermented soybeans, differed from the other meat substitutes in the amount of iron available for absorption by the body. This was expected, as the fermentation of tempeh uses microorganisms that break down phytates. Mycoproteins stood out for their high zinc content, without containing any known absorption inhibitors. However, according to the researchers, it is still unclear how well our intestines can break down the cell walls of mycoprotein how this in turn affects the absorption of nutrients.

Chalmers.se

* The protein is restructured by high pressure and temperature