WASHINGTON, D.C.—U.S. and Canadian food labeling regulations should be modernized to eliminate the requirement to measure protein digestibility in rats to substantiate protein content claims for conventional foods, according to a new article led by the Physicians Committee for Responsible Medicine and published in Current Developments in Nutrition. The authors argue this approach disadvantages many plant-based foods in the marketplace, even as nutrition experts encourage higher intake of legumes, nuts, seeds, and other plant protein sources.
That’s because most plant protein sources are less digestible than animal proteins. Plant cell walls can block digestive enzymes from reaching plant proteins, and factors inside the cell, like antiproteases, can prevent them from breaking down proteins. However, the authors point out that cooking and other types of processing can improve digestibility.
In the U.S., making a protein claim, like “good source of protein,” requires reporting not just the amount of protein, but also the percentage of the Recommended Daily Allowance of protein a serving provides. This “% Daily Value” is based on the amount of protein corrected for both its amino acid profile and for its digestibility. If data are unavailable, regulations require measuring digestibility in rats.
“Protein claims influence consumers’ choices at the point of purchase, but the current regulatory framework makes it less likely they will choose plant-based protein sources. It also raises ethical concerns for consumers who avoid both animal-based foods and products tested on animals,” says Joseph Manuppello, lead author and a research analyst at the Physicians Committee for Responsible Medicine. “For most people, who already consume enough protein from varied sources, the amount of protein per serving is an appropriate basis for protein content claims.”
The article reports that replacing the animal in vivo digestibility assay with validated in vitro methods could substantially reduce animal use. In Canada alone, the authors note that thousands of foods with protein claims entered the market in recent years.
At a roundtable discussion convened by the Physicians Committee, participants identified two such promising methods based on estimating digestibility by measuring the pH when protein is broken down by enzymes in vitro. Because of its long history of use and agreement with in vivo results, the Physicians Committee is planning to sponsor one such method in a U.S. Food and Drug Administration qualification program. The article recommends updating regulations to allow authorities to accept such methods where digestibility data are unavailable, while moving away from digestibility measurement for conventional foods intended for adults and older children.
“Protein deficiency is not a significant concern in North America, but diets high in saturated fat and low in fiber are,” says co-author Anna Herby, DHSc, RD, CDE, nutrition education specialist at the Physicians Committee. “Removing barriers to plant-based foods making protein claims can help align consumer choices with a dietary pattern that supports health and reduces risks of chronic disease, like cardiovascular disease and type 2 diabetes.”
The authors also highlight that other jurisdictions, including Australia and New Zealand, the European Union, and China and South Korea, rely primarily on the amount of protein to substantiate protein claims, an approach they argue better aligns labeling regulations with current nutrition guidance and supports innovation in plant-based proteins.
