Anyone who cares about maintaining muscle mass should care about the quality of their dietary protein, according to a scientific review published in Nutrition & Metabolism.
Researchers from the MacMaster University reviewed the current findings to examine the effects of the quality of supplemental protein on changes in muscle mass, strength and body composition when combined with strength training.
This comprehensive inquiry suggests that protein sources providing leucine (an essential amino acid) are the strongest determinant of muscle protein synthesis and likely muscle growth.
The result was based on a new proposed method, which evaluates protein quality using the protein’s indispensable (or essential) amino acid composition and its digestibility.
Leucine is not only a building block for protein, but also a trigger for working muscles to synthesize more protein.
Essentially, it turns on muscle protein synthesis like a light switch so that over time, there could be greater gains in lean body mass and strength, and subsequently, body composition improvements.
Proteins with the greatest content of leucine include whey protein isolate or concentrate.
Whey protein is a milk protein that is considered high-quality due to its amino acid profile and high score for digestibility.
Based on the culmination of data inspecting protein types and muscle protein synthesis, whey protein rated higher than other protein sources such as soy, pea or rice.
Researchers suggest that the outcome of this review isn’t just applicable to strength trainers.
As people age, muscle loss becomes prevalent if we don’t thwart the decline. Leucine-rich whey protein supplementation, combined with resistance exercise, may be one way to help preserve muscle mass throughout the lifespan.
More research is needed to further test proteins based on their quality, digestibility and amino acid profile, as well as to identify their impact on the aging population.
Currently, consumers should reach for a leucine-containing protein supplement, like whey, to maximize gains from hard workouts.
Citation: Phillips SM. (2016). The impact of protein quality on the promotion of resistance exercise-induced changes in muscle mass. Nutrition & Metabolism, 13: 64. DOI: 10.1186/s12986-016-0124-8.
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