Post-meal increases in leucine play a critical role in stimulating muscle protein synthesis, and therefore supporting the growth and maintenance of muscle mass. Similarly, plasma essential amino acids (EAAs) play an important role in supporting muscle growth.
In the current study, the authors compared post-meal amino acid levels after subjects consumed whey or three separate plant-based protein blends. All four treatments had the same total amount of leucine, EAAs, and a protein digestibility corrected amino (PDCAA) score of 1.0. As a result, the plant proteins required a total protein dose of 33-34g, while subjects consumed only 24g of whey.
In the 4 hours after feeding, plasma peak leucine and EAA values were significantly higher for whey protein than for all other proteins. While the plant proteins were safe, well-tolerated, and caused notable increases in plasma leucine and EAAs, they were not equivalent to whey.
The bottom line: There’s absolutely nothing wrong with plant proteins, and it’s important to remember that this study did not directly measure hypertrophy, or even protein synthesis. However, this study seems to add a little more evidence to the literature suggesting that lifters on plant-based diets may want to shoot for relatively higher protein intakes if hoping to maximize muscle mass.