Protein from plant-based ‘meat’ may be less well absorbed by the body

The protein found in meat alternatives made from wheat and soy may be less well absorbed by the small intestine into the bloodstream than protein from chicken breasts

By Carissa Wong

In a laboratory experiment, proteins in a meat substitute (left) were less well absorbed by gut cells than proteins from chicken breast (right)

Adapted from Journal of Agricultural and Food Chemistry 2022

Dietary protein may be less well absorbed from plant-based meat alternatives than protein from chicken breast.

“This work opens a door on the nutritional properties of plant-based meat alternatives,” say Da Chen and Osvaldo Campanella at The Ohio State University. “Our study suggests that proteins from chicken have better digestibility compared to those of meat analogs prepared using soy and wheat proteins.”

In their laboratory-based experiment, Chen, Campanella and their colleagues grew a layer of human gut cells on scaffolds that divided several dishes into two chambers. They then digested a plant-based meat alternative and a cooked chicken breast using enzymes from the stomach and small intestine, before adding each digested product to one chamber in each dish.

Next, the team measured the amount of protein fragments – or peptides – that passed through the layer of gut cells to reach the opposite chamber in each dish, representing the absorption of protein through the gut.

Within four hours of being added to the dish, the longest typical transit time for food in the small intestine, about 2 per cent less protein from the plant-based meat alternative had transferred through the gut cells, compared with the chicken breast. Although a small percentage difference, statistical analysis suggests this result was not a chance finding.

Eating meat alternatives may therefore result in less protein being absorbed through our gut wall into our bloodstream. The team did not assess whether this reduced absorption leads to protein deficiency.

In a second part of the experiment, the team analysed the digested foods’ peptides, discovering that protein fragments from chicken breast are smaller and more soluble in water than meat alternative peptides.

“It has been shown that peptides with smaller sizes and higher [solubility] can transfer more easily through [these gut] cells,” say Campanella and Chen.

However, the laboratory model is a highly simplified version of the gut that lacks the mucus lining found in the body, according to Campanella and Chen.

“In the gut, the peptides need to cross a mucus layer…which serves as a filter… before reaching the intestinal epithelium cells. [We tested protein absorption] without consideration of the mucus layer,” they say.

Protein absorption may also differ in the large intestine, where food can remain for up to 24 hours, a timeframe that was not assessed in the experiment.

What’s more, protein uptake from plant-based meat alternatives and other meats beyond chicken breast depends on their individual protein composition and processing.

Despite their results, the Ohio State University team maintains that plant-based meat alternatives are probably a good protein source.

“Even though plant-based meat alternatives had fewer peptides being absorbed, they still provide a good profile of amino acids and could be an adequate complement to a well-balanced diet,” say Campanella and Chen.

The researchers are now working to improve the nutrition absorbed from plant-based meat alternatives.

“Plant-based foods should be carefully designed to ensure that they have similar or better nutritional profiles than animal-based ones,” says David Julian McClements at the University of Massachusetts Amherst.

Journal reference: Journal of Agricultural and Food Chemistry , DOI: doi.org/10.1021/acs.jafc.2c01711