Robert Wolfe in his article found in the Journal of the International Society of Sports Nutrition titled; Branched-chain amino acid and muscle protein synthesis in humans: myth or reality? wrote a frank appraisal of the worth of BCAA's and based on the title of this blog post you can guess what the findings were. Before we jump into exactly what those findings were lets understand what would motivate someone to try BCAA's in the first place. The common thinking or "bro" thinking is that taking Leucine (1 of the 3 "vital" BCAA's) is thought to trigger increases in muscle protein synthesis (MPS). It is important to note however that this thinking came from a bunch of rat studies. Therefore the thinking is that by taking BCAA's between meals you can consistently be stimulating MPS. More MPS = more muscle, right?
In order for MPS to occur you need to understand the mechanism of muscle protein turnover. In order for MPS to occur you need all Essential Amino Acids (EAA) and the Branched Chain Amino Acids. Therefore, if you just consume the BCAA's typically found in BCAA supplements you still need the EAA's to create MPS. Guess where this comes if you only consume BCAA's with no other EAA's? That's right, muscle. The body is forced to turnover its muscle to create the EAA's to combine with the BCAA's to create new muscle. Simply put, you are becoming catabolic (muscle loss) in order to try and make something of the BCAA's. This is exactly what we are trying not to do. We want to build muscle. Not lose it to try and create more...…
In conclusion Wolfe writes
"We conclude that the claim that consumption of dietary BCAA's stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted."
What you should be doing instead is eating whole protein sources and using a whey or casein protein. In fact a regular 30 gram serving of whey will provide you the same levels of leucine, valine and isoleucine (the 3 BCAA's found in supplements) with the added benefit of the EAA's, therefore stimulating MPS and building muscle rather than needing for muscle turnover (catabolism) to provide the necessary building blocks of muscle.
Simple take home message, lift heavy, eat your steak and enjoy that whey protein shake after your lifting. Nothing fancier required!
Ref: Wolfe, Journal of the International Society of Sports Nutrition (2017) 14:30