The study reveals that the nutritional value of meat alternatives currently on the market is often inadequate, based on factors such as raw material selection (often imported soybeans), processing methods (antinutrient content), and added ingredients (fat quality, salt).
The emergence of plant-based protein options as alternatives to meat has grown significantly as more individuals adopt a plant-based diet. However, the nutritional value of these products is still a concern. Study from Chalmers University of Technology It was found in Sweden that many of the meat substitutes sold in Sweden are high in iron, but it is in a form that the body cannot absorb.
Professor Anne-Sophie Sandberg, Department of Biology and Biological Engineering, Chalmers University of Technology. Credit: Chalmers
A diet consisting largely of plant foods such as root vegetables, pulses, fruits, and vegetables has an overall low climate impact and is also associated with health benefits such as reduced risk of age-related diabetes and cardiovascular disease, as has been shown in several large studies. . But there have been far fewer studies on how people’s health is affected by eating products based on what are known as plant proteins.
In the new study by Chalmers, a research team at the Department of Food Science and Nutrition analyzed 44 different meat substitutes sold in Sweden. The products are made primarily from soy and pea protein, but also include fermented soybean product and mycoproteins, that is, proteins from fungi.
“Among these products, we saw great variance in nutritional content and how sustainable they were from a health perspective. In general, the estimated absorption of iron and zinc from the products was very low. This is because these meat alternatives contain high levels of phytates, antinutrients that inhibit the absorption of minerals in body, says Cecilia Meyer-Lappa, lead author of the study, who recently defended her thesis on dietary restrictions for switching from animal protein to plant-based protein.
The body loses essential minerals
Phytates are found naturally in beans and grains – they accumulate when proteins are extracted for use in meat substitutes. In the digestive tract, where minerals are absorbed, phytates form insoluble compounds containing essential dietary minerals, particularly non-heme iron (Iron found in plant foods) and zinc, which means they cannot be absorbed in the intestine.
Iron and zinc also accumulate in protein extraction. This is why high levels are listed among the ingredients of the product, but the minerals are bound to the phytates and cannot be absorbed and used by the body,” says Cecilia Meyer-Laba.
Dr. Cecilia Meyer-Labba, Department of Biology and Biological Engineering, Chalmers University of Technology. Credit: Martina Butorac/Chalmers
Iron deficiency among women is a widespread global problem. In Europe, 10 to 32 percent of women of childbearing age and about one in three adolescent girls in secondary school in Sweden are affected. Women are also the group most likely in society to switch to a vegetarian diet and eat the least amount of red meat, which is the main source of iron that is easily absorbed in the digestive tract.
Obviously, when it comes to minerals in meat alternatives, the amount available for absorption by the body is a very important consideration. You can’t just look at the ingredients list. Some of the products we studied are fortified with iron but still inhibited by phytates. We believe that making nutritional claims about those nutrients that can only be absorbed by the body can create incentives for industry to improve these products, says Ann-Sophie Sandberg, professor of food science and nutrition at Chalmers and co-author of the study.
The food industry needs new ways
Tempeh, which is made from fermented soybeans, differed from other meat alternatives in the amount of iron available for the body to absorb. This was expected, since the fermentation of tempeh uses microorganisms that break down phytate. Fungal proteins were characterized by their high zinc content, without containing any known absorption inhibitors. However, according to the researchers, it is still not clear how our gut can break down the cell walls of the fungal protein and how this, in turn, affects the absorption of nutrients.
Plant-based foods are important for the transition to sustainable food production, and there is huge development potential for plant-based meat alternatives. The industry needs to consider the nutritional value of these products and take advantage of and improve known process techniques such as fermentation, but also develop new ways to increase the absorption of various important nutrients,” says Cecilia Meyer-Laba.
Production of plant proteins
- Most plant protein products on the market are based on protein extracted from a cultivated plant, such as a soybean, and separated from other plant ingredients.
- The protein is then subjected to high pressure and temperature, which restructures the proteins, known as structure so that a more meaty and chewy product can be obtained along with the other ingredients.
- Chalmers’ study shows that the nutritional value of meat alternatives available today is often deficient depending on the choice of raw materials (often imported soybeans) and processing conditions (antinutrient content), and on additives (fat and salt quality).
- A 150-gram serving of meat alternative contributes up to 60 percent of the maximum recommended daily amount of salt, which is 6 grams according to Northern Nutrition recommendations.
Reference: “Nutritional composition and estimated bioavailability of iron and zinc for meat substitutes available on the Swedish market” By Inger Cecilia Meyer-Lappa, Hannah Steinhausen, Linnea Almius, Knud-Erik Bach-Knudsen, and Anne-Sofi Sandberg, Sept. 21, 2022, Available Here. Nutrients.
DOI: 10.3390/nu14193903
The study was funded by the Birtibus Foundation, the Swedish Research Council, and Västra Götaland Region.