When it comes to plant-based protein products, one question seems to concern food developers more than any other: How digestible are they?
“Some plant-based proteins are not well digested,” says Laetitia Guérin-Deremaux, Head of Nutrition and Health R&D at Roquette. Her team wanted to develop stronger scientific data that could reassure consumers about the great digestibility of NUTRALYS® pea protein.
After all, digestibility is about getting the body what it needs. “Healthy adults should have 0.83g of protein per kilogram of body weight, per day,” Guérin-Deremaux says. “If the food you’re eating is not digested, it could mean you do not have the protein you need every day.”
To show consumers NUTRALYS® pea protein was a good source of amino-acids, Guérin-Deremaux’s team wanted to gather the most robust scientific data possible. Doing so meant using human subjects and finding a way to safely track and measure protein as the body is digesting it.
The resulting study* was groundbreaking – and results were even more positive than expected. Here’s how a team of scientists made it happen.
Observing protein in the body
To observe protein digestion, researchers would have to gather data where that actually takes place.
“Protein breaks down in the small intestine,” Guérin-Deremaux says. “A protein is a combination of amino acids linked together. To use it, your body must break down that linkage. The small intestine is where that happens.”
But how do you measure undigested protein in the small intestine?
And how do you guarantee the protein found there is part of your study and not just left in the body from a previous meal?
The team at Roquette partnered with a research group at INRAE in France. They chose a methodology proposed by the World Health Organization (WHO) and the U.N.’s Food and Agriculture Organization (FAO) for obtaining robust data on digestion.
To begin, Roquette developed a special version of NUTRALYS® pea protein that was “tagged” with a stable isotope, making it recognizable and easy to distinguish from any other foods that might still be present in their human volunteers. They also tagged samples of casein, a milk protein, to be used as a control group.
Half of the group of 15 volunteers would be asked to consume the casein, and the other half would be asked to consume the pea protein. Researchers would gather data on digestion and compare.
First, volunteers were asked to fast to reduce the amount of previously eaten food still present in their bodies. They arrived the day before the trial so that a naso-ilieal tube could be run through the nose into the ilea, the terminal portion of the small intestine. This tube would be used to collect undigested food that had passed through the small intestine, so researchers could see how much isotope-tagged protein or amino acids might remain.
Volunteers were fed 9 times throughout the day, eating a small portion of mashed potatoes that contained either the casein or the pea protein. Meals started at 10am and ended at 2pm.
At 6pm, the naso-ileal tube was removed. By that time, researchers had gathered data on intestinal activity for 8 hours.
And that meant they had all the data they needed.
“We knew the quantity of protein consumed by volunteers, and we knew the amount removed from the small intestine,” Guérin-Deremaux says. “So we made the calculation.”
A high-quality protein
Research data returned an amino acid digestibility of 94% for our pea protein, compared to 97% for casein. Researchers also calculated the Digestible Indispensable Amino Acid Score (DIAAS), which is a new way to look at protein quality introduced by the FAO in 2013, and found NUTRALYS® had a DIAAS of 100% compared to 145% for that of casein in the study.
Casein is considered as the “gold standard” for protein quality in human nutrition, Guérin-Deremaux says. And the pea protein results are strong enough to consider it as a viable alternative or replacement of animal protein in many cases because DIAAS of 100% means that the pea protein provides all the essential amino acids that our body needs to function properly.
“Even for those of us in the pea protein business, this was a surprisingly good result,” she says. “I think this quality comes from our process. We’re extracting protein from the pea in a way that makes it much more digestible by the body.”
That’s good news for Roquette and Roquette’s customers. But it’s also an important step forward for the plant protein industry as a whole.
“We are the first in plant-based protein to have this kind of data using this methodology,” Guérin-Deremaux says. “There’s a limited number of science teams able to do this kind of study. I’m proud of what the Paris group accomplished.”
The study on digestibility in humans was published in the American Journal of Clinical Nutrition in October 2021.
*NUTRALYS® health benefits are supported by one single clinical study. Food manufacturers who would like to use NUTRALYS® pea protein for these benefits will have to run its own studies based on its own formulation.
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