Study compares protein quality of meat-based burgers and plant-based burgers

Plant-based burgers claim that they offer protein similar to their animal-based counterparts. However, protein is expressed on present-day nutrition labels as a single generic value expressed in grams. This can be misleading as the human body does not utilize “protein” per se. Rather, it requires essential amino acids that are part of proteins, however, the concentration and digestibility of amino acids are diverse among protein sources.

Image Credit: University of Illinois College of Agricultural, Consumer and Environmental Sciences.

About 10 years ago, the UN’s Food and Agriculture Organization (FAO) developed the digestible indispensable amino acid score (DIAAS), a new standard for protein quality, to account for the differences. It concentrates particularly on the digestibility of essential amino acids and is intended to provide more precise tools for nutritionists and food assistance programs globally.

Recent research from the University of Illinois and Colorado State University took advantage of the DIAAS system to comprehend protein quality in pork and beef burgers and plant-based burgers from Beyond Meat^® and Impossible^™.

The scientists fed 80% and 93% lean beef burgers, pork burgers, pea-based Beyond Burger, and soy-based Impossible Burger to pigs—the FAO’s advocated research subject for DIASS research. The researchers then evaluated the digestibility of individual essential amino acids and utilized those digestibility scores to compute DIAAS values.

The beef and pork burgers served without buns scored as “excellent” protein sources (DIAAS scores 100+, for individuals of all ages). The Impossible Burger served without a bun, also scored as an excellent source of protein for ages three and above, but not for children less than three years old. The bunless Beyond Burger had a score of 83 and was regarded as a “good” protein source for ages three and up.

We have previously observed that animal proteins have greater DIAAS values than plant-based proteins and that is also what we observed in this experiment.”

Hans H. Stein, Study Co-Author and Professor, Department of Animal Sciences, University of Illinois

Hans H. Stein is also an associate professor at the Division of Nutritional Sciences at Illinois. The research was published in the European Journal of Nutrition.

Burger patties are mostly consumed along with the bun; hence the scientists also examined the protein quality of patties and buns together. As grain products—like hamburger buns— provide low protein quality, feeding the bun and the patties together decreased the DIAAS values.

Intaking the Impossible Burger along with the bun decreased the DIAAS score to “good” (for ages three and above). However, when pork or 80% lean beef patties were eaten together with buns, DIAAS values remained the same or were above 100 for the above-three age group. This indicates that the requirements for all essential amino acids were met by these combinations.

There was a greater DIAAS value of mixing either the pork or beef burger with the bun – values of 107 and 105 respectively, for the over-three age group—than there was for the Impossible Burger, which had a DIAAS value of 86 if consumed with the bun.”

Mahesh Narayanan Nair, Study Co-Author and Professor, Colorado State University

He further adds, “That means you need to eat 15% more of the Impossible Burger–bun combination to get the same amount of digestible amino acids as if you eat the pork-based or the beef-based burgers. And if you have to eat more, that means you also get more calories.”

It’s particularly children, teenagers, lactating women, and older people who are at risk of not getting enough amino acids. Results of this experiment, along with previous data, demonstrate the importance of getting animal-based proteins into diets to provide sufficient quantities of digestible essential amino acids to these populations.”

Hans H. Stein, Study Co-Author and Professor, Department of Animal Sciences, University of Illinois

“This is also really important in developing countries where there may be little access to animal-based proteins, particularly for children. In some countries, a majority of children are amino acid deprived. That’s extremely serious because, if children don’t get enough amino acids, their brain development can suffer. It's especially important in those cases to design a strategy for getting high-quality proteins into diets for children,” states Stein.