Human cells take in less protein from plant-based meat than chicken, study flags

24 Jun 2022 --- Peptides from plant proteins such as soy and wheat gluten used in alt-chicken display less water-solubility than animal protein and are not absorbed as well by human cells. These are the key findings of a new study into the nutrient absorption of plant proteins conducted by the American Chemical Society (ACS), a nonprofit organization chartered by the US Congress.

Two experts on the topic spoke to FoodIngredientsFirst. “This study adds another piece of data at the molecular level to conclude specifically that these particular meat substitutes did not break down into peptides as efficiently as the meat proteins, and therefore are not as digestible for body growth and function compared to meat proteins,” says Dr. Robert McGorrin.

The importance of the absorption of peptides by human cells is tied to their transport across the gut into the bloodstream for nutrient uptake. Water solubility enhances transport and absorption of peptides by human cells. 

Meat alternative modeling
Researchers in ACS’ Journal of Agricultural and Food Chemistry report that proteins in a model plant-based substitute were not as accessible to cells as those from meat.

“The principal finding of this research was that meat analogs prepared from a mixture of soy protein concentrate and wheat gluten protein were not as digestible compared to the meat from chicken breast,” adds McGorrin.

“This is not surprising, since previously published tables of food protein ingredients have shown that milk, egg, and chicken proteins are more digestible than soy protein,” he says.The ACS study provides insights into what the potential nutritional consequences are of switching from an omnivore diet to a plant-based diet. 

However, the consequences of weaker absorption are slower growth or cellular functioning by the body.

“The conclusions of this study suggest that future developments are needed to improve the nutritional value and digestibility of plant proteins compared to meat proteins,” McGorrin continues.

This could be achieved by plant breeding, reformulation or blending of the vegetable protein ingredients to correct for the protein deficiencies. The authors suggest running additional in vivo studies to confirm the conclusions of the in vitro study.

Further study required on plant-based meat substitutes
The researchers created a model meat alternative made of soy and wheat gluten with the extrusion process, used in the average production of alt-meats, in which plants are dehydrated into a powder and mixed with seasonings, heated, moistened and processed through an extruder. 

During the ACS experiment, the material displayed long fibrous pieces when sliced, akin to that of chicken. Cooked pieces of the substitute and chicken meat were ground up and broken down with an enzyme that humans use to digest food. 

Dr. D. Julian McClements adds: “Proteins are made of chains of amino acids. These chains must be broken down inside our gastrointestinal tract before they can be absorbed. This study (using a simulated in vitro digestion model) shows that the plant proteins in meat analogs were digested less than the animal proteins in real meat.”

“If the protein is digested less, then it will be absorbed by the body less. If your diet was limited in protein, then this could be a problem. But this is rarely the case in developed countries,” he says.

Because this particular in vitro study uses one type of meat analog and one type of meat it is difficult to generalize to all cases. 

“The real human gastrointestinal tract is much more complex than the model used. Consequently, experiments would have to be carried out using human feeding studies to see if similar effects were observed and determine the nutritional consequences,” McClements explains.Next the ACS researchers want to identify other ingredients that can boost peptide uptake in meat substitutes. 

“However, this kind of study is important because it provides insights into what the potential nutritional consequences are of switching from an omnivore diet to a plant-based diet that is more sustainable,” he outlines.   

The study was funded by the College of Food, Agricultural, and Environmental Sciences at Ohio State University. 

Need for healthier alt-meats
With the new knowledge gained from the experiment, the researchers believe the next step is to identify other ingredients that can boost the peptide uptake of plant-based meat substitutes. The team believes the knowledge can be used to develop healthier products.

The findings are reported in “Characterization and Cellular Uptake of Peptides Derived from In Vitro Digestion of Meat Analogues Produced by a Sustainable Extrusion Process”. 

The researchers conducted a similar study in 2021, “Digestibility and gastrointestinal fate of meat versus plant-based meat analogs: An in vitro comparison,” published in Elsevier.

The growth of the plant-based meat sector was evident at IFFA 2022 as traditional meat companies steadily branch out with a variety of plant-based protein innovations. Making these product lines healthier is a natural next step for producers in the segment.

Shanghai-based Haofood has taken its proprietary protein Innotein to the next phase of growth following a cash injection of US$3.5 million. The company will diversify its channel sales strategy and advance its R&D infrastructure facility to grow the domestic business and expand through Asia.

Skinny Butcher, Wow Bao, Golden West Food Group and Valor Siren Ventures are teaming up to bring a soy-free range of plant-based poultry to supermarkets and virtual restaurants in the US.

By Inga de Jong