Plant-based meat proteins may not be absorbed as well

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Plant-based meat substitutes may be good sources of protein but may not be easily absorbed, new research suggests. Sophia Hsin / Stocksy
  • The researchers compared the protein absorption between meat of plant origin and chicken meat.
  • Protein absorption was greater for chicken meat than for plant-based meat.
  • The researchers concluded that the nutritional value of plant-based meats could be improved by changing the formulation and production conditions.

In recent years, plant-based meats have become more common as a way to “enjoy the taste of meat” without harming animals or the environment.

Although the low fat and cholesterol levels of plant-based meats can help reduce obesity and the risk of cardiovascular disease, studies show that they may be less digestible than meat of animal origin.

Knowing more about how plant proteins are digested could help assess their feasibility as a primary source of dietary protein.

Recently, researchers compared protein absorption from plant-based meat with chicken. They found that plant proteins were less absorbed during an in vitro digestion process than chicken proteins.

The study was published in Journal of Agricultural and Food Chemistry.

For the study, the researchers created a plant-based “chicken” meat from soy concentrate and wheat gluten. The final product had a protein content of 24.2%.

The vegetable meat was then cooked alongside the chicken, ground to simulate the chewing process and passed through a 2.36mm sieve to avoid sample size induced digestion effects for the two samples.

The resulting “lumps of meat” were then subjected to various in vitro tests to model protein absorption during digestion.

From these tests, the researchers found that the water solubility of plant-based meats gradually increased during in vitro digestion, reaching around 8% after gastric digestion and then 14% at the end of intestinal digestion.

They found, however, that chicken peptides were consistently more water soluble than plant-based peptides.

Furthermore, they noted that of the 110 peptides identified in vegetable meat, about 50% remained after the digestion process.

Meanwhile, of the more than 500 peptides identified in chicken meat, only 15% remained after digestion. This, they wrote, suggested that peptides in chicken are more easily absorbed than those of plant origin.

When asked what might explain why human cells absorb less protein from plant meats than chicken, Dr. Da Chen, a postdoctoral researcher at Ohio State University and author of the study, said. Medical News Today:

“Proteins are digested before being absorbed by human intestinal epithelial cells. After digestion, proteins mainly become peptides. The size and polarity of peptides have been reported to be closely associated with their uptake.

“In our study, the peptides produced by digesting plant-based meats were larger [and less water soluble]which causes them to pass through epithelial cells slower than in chicken, resulting in less absorption efficiency, “he explained.

Professor VM (Bala) Balasubramaniam, of the Ohio State University Department of Food Science and Technology, who was not involved in the study, agrees.

“I agree with the author’s observation on this. As they noted, chicken meat protein showed better swelling capacity, which helps promote digestive enzymes. Soy proteins contain some anti-nutritional factors (e.g. phytates and tannins) that can limit the hydrolysis of proteins [water solubility],” She said MNT.

“Furthermore, the structural differences between plant and animal foods can also affect how proteins are released,” he added.

David Julian McClements, a distinguished professor in the University of Massachusetts Department of Food Sciences who was not involved in the study, noted that digestibility and absorption depend on several factors, including:

  • protein type
  • denaturation of proteins
  • protein aggregation
  • effects of the food matrix
  • anti-nutritional factors
  • processing and cooking methods

He then stated that the results of this study may not be applicable to all plant-based meat comparisons.

An example of this is that wheat gluten is not water soluble and has stiffer structures than soy and chicken proteins, making it less digestible. Since the vegetable meat in this study was made up of 28% wheat, the present results may not apply to vegetable meat obtained exclusively from soybeans.

The authors concluded that the nutritional value of plant-based meats could be improved by changing the formulation and production conditions.

“When evaluating the quality of plant-based meat, not only the texture but also the protein nutrition should be considered,” said Dr Da Chen. MNT.

“The results of the study begin to provide some insight into how different plant and animal proteins affect human health. This will enable food processors to understand the benefits and limitations of different food processing technologies and ingredients. “
– prof. Balasubramaniam

Dr. Chen also pointed out that plant-based meats were still viable sources of protein.

“For consumers, plant-based meats would still provide valuable protein nourishment because they contain a good amino acid profile. The fact that consumers have to eat more plant-based meat to get an equivalent diet is not the subject of this study because it depends on the daily protein intake, which was not conducted, “he said.

When asked about the limitations of the study, Dr. Chen said: “We have only used soy / wheat protein as the main protein source for the production of meat analogs, for those that produce with other proteins or different formulations, the results may be different.”

“Our studio [also] used for in vitro digestion only, it may show some differences to that of in vivo digestion. Future [studies] it should focus more on clinical trials, “he added.

However, Dr. McClements noted that this study, and others like it, are crucial. He said: “If we want to replace animal foods with plant-based alternatives, we don’t want to have any negative effects on nutrition and human health.”

“Consequently, it is important to design plant-based foods to have similar or better nutritional profiles and digestibility / absorption behaviors than the animal-based foods they are designed to replace,” he concluded.