Sports Ingredient Sustamine May Inhibit Muscle Protein Breakdown: Rat Study


The researchers suggest exploring the combination of Sustamine and whey protein for muscle repair.

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Sustamine, a combination branded amino acid ingredient common in food and sports supplements, has been touted to help repair and rebuild damaged muscles and to renew and rehydrate the body following exercise. In a new rat study published in the journal Amino Acids,1researchers posit that Sustamine’s role in muscle-protein repair may in part be due to an ability to inhibit muscle-protein breakdown. Supplier Kyowa Hakko USA (New York City) says this rat study is one of the first to demonstrate the L-alanyl-L-glutamine ingredient’s role in muscle protein degradation.

In the study, conducted by University of Texas at Austin researchers, 89 Sprague-Dawley rats performed resistance ladder-climbing exercises. Immediately thereafter, subjects were given one of four interventions: 1) placebo, 2) 0.4 g/kg of whey protein, 3) a low dose of Sustamine (0.1 g/kg), or 4) a high dose of Sustamine (0.5 g/kg). Researchers then collected blood samples post-recovery to analyze blood lactate levels and analyzed subjects’ flexor hallucis longus muscle (a muscle used for climbing) for protein synthesis and degradation.

According to researchers, Sustamine appeared to inhibit signaling proteins that play a role in protein degradation. Both doses of Sustamine “altered, immediately post exercise, the phosphorylation state [protein structure] of signaling proteins in a manner that theoretically should reduce muscle protein breakdown,” they wrote.

Where Sustamine helped to slow muscle-protein breakdown, the researchers determined that whey protein helped spur muscle protein synthesis. Specifically, they wrote, whey protein “accelerated the phosphorylation of proteins in the mTOR-dependent signaling pathway, thereby theoretically activating muscle protein synthesis.”

The researchers suggest exploring the combination of Sustamine and whey protein for muscle repair. “Together, these findings suggest that a combination of whey protein and Sustamine supplementation post-exercise might result in the phosphorylation of metabolic regulatory enzymes in a manner that would increase muscle protein synthesis and decrease muscle protein breakdown, thereby maximizing muscle protein accretion.”


Jennifer Grebow
Nutritional Outlook magazine



1. Wang W et al., “L-alanylglutamine inhibits signaling proteins that activate protein degradation, but does not affect proteins that activate protein synthesis after an acute resistance exercise,” Amino Acids, vol. 47, no. 7 (July 2015): 1389-1398.

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