Nutrition News: Plant Protein
Having a more plant-forward diet is important for a lot of health reasons but leaving out meat altogether may not be best for children, teenagers, breastfeeding women and older Americans.
In a study from the University of Illinois and Colorado State University, researchers found that the protein in plant-based burgers wasn't digested as much as that found in meat-based burgers due to the concentration and digestibility of the amino acids.
A decade ago, the U.N. Food and Agriculture Organization developed a standard for protein quality called the Digestible Indispensable Amino Acid Score (DIAAS). It focuses on the digestibility of essential amino acids (the building blocks of protein).
Researchers used the DIAAS system to understand protein quality in beef and pork burgers and plant-based burgers from Impossible and Beyond Meat.
The researchers fed pork burgers, 80% and 93% lean beef burgers, the soy-based Impossible burger and pea-based Beyond burger to pigs, the FAO's recommended research subject for DIAAS studies. Then they measured digestibility of individual essential amino acids and used those digestibility scores to compute DIAAS values.
Both beef and pork burgers, served without buns, scored as "excellent" sources of protein (DIAAS scores 100-plus, for people of all ages). The Impossible Burger, when served without a bun, also scored as an excellent protein source for ages 3 and up, but not for children less than 3 years old. With a value of 83, the bunless Beyond burger was a "good" source of protein for ages 3 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," wrote Hans Stein, professor in the Department of Animal Sciences and the Division of Nutritional Sciences at the University of Illinois and co-author. The study was published in the European Journal of Nutrition.
Burger patties are typically eaten with a bun, so the researchers also looked at the protein quality of patties and buns together. Because grain products, like hamburger buns, offer low protein quality, feeding the bun and the patties together reduced DIAAS values.
It's particularly children, teenagers, breastfeeding women and older people who are at risk of not getting enough amino acids, according to Stein.
The study has implications for developing countries where there may be little access to animal-based proteins, particularly for children. In some countries, Stein said most children are amino acid deprived. Without enough amino acids, brain development can suffer.