What exactly is BCAA?
BCAA (branched-chain amino acid) are three branched-chain exogenous amino acids – leucine, isoleucine, and valine.
Amino acids are component particles of protein – both the protein which we consume with our meals and that which forms part of our muscles. Amino acids may be divided into two types: endogenous and exogenous – the former are produced by our body itself, the latter must be provided from the outside.
Exogenous amino acids (i.e. those which the human body cannot produce itself) are necessary to maintain and build muscle mass. That is why athletes and amateur sportspeople are recommended to increase protein intake in their diets, paying special attention to the wholesome protein (i.e. protein which contains all exogenous amino acids).
HERE you’ll find 3 ideas for recommended post-workout protein-rich meals.
But why have those three (BCAA) among nine exogenous amino acids gained so much popularity?
How does BCAA work?
Leucine, isoleucine, and valine constitute over 1/3 of all exogenous amino acids in muscles, which in itself is an argument for their consumption. However, it is leucine that is the most important among those particles, because it forms the basis for the leucine threshold concept.
Research has shown that the consumption of leucine-rich protein better stimulates muscle protein synthesis compared to the protein with lower leucine content (regardless of the content of other amino acids). Leucine acts a little like a signalling device in the muscle tissue, when it reaches the muscles, it lets them know that they should prepare for increased protein production. By analogy, according to the famous study which formed the basis for coining the leucine threshold concept, the consumption of even a small amount of protein (a little over 6 g) with leucine may stimulate the production of muscle protein at the same level as the consumption of a larger portion (25 g) of pure protein.
In principle, this sounds like a perfect strategy for building muscle mass: no matter how much protein you consume, it is enough to add the appropriate amount of leucine in the form of supplement et voilà! – muscle mass gain guaranteed. It’s a simple, fast, and economical solution for athletes and it guarantees high demand for dietary supplements (to the manufacturers’ delight).
BCAA – is it really effective?
You cannot get water out of a stone. Prolonged consumption of low amounts of protein, such as a little over 6 g per meal, with or without leucine, will result in a situation where your body will simply have no substrates to produce protein.
BCAA will of course stimulate muscle protein synthesis (mainly thanks to leucine content), but the effect will be much worse than if you simply consumed wholesome protein containing all exogenous amino acids.
It is true that BCAA constitute over 1/3 of amino acids in the muscle protein, however, there are still 2/3 to be accounted for. Therefore, the worst case scenario of BCAA supplementation is using it instead of a portion of wholesome protein.
Don’t forget that wholesome protein contains all nine exogenous amino acids, including leucine, isoleucine, and valine. That’s why every portion of wholesome protein will also provide us with a portion of BCAA. According to the leucine threshold theory, increased consumption of leucine (over the “threshold”) does not increase muscle mass, there are no additional benefits of exceeding the threshold. The limit is individual and depends on many factors, so it is impossible to provide a universal level of the leucine threshold in grams.
Which is better – BCAA or protein?
Imagine a glass full of water. Adding extra portions of water to the container will cause the water to overflow (be wasted) while the glass will not change its capacity, it will still hold the same, specified amount of water.
Surely, someone who wishes to build their muscle mass already takes great care about the amount of protein in their diet. Supplementing BCAA while consuming the right amount of wholesome protein is similar to pouring water into a full glass.
Excess amino acids will not make your muscles grow better and faster. If your body receives the right amount of leucine, isoleucine, and valine from wholesome protein (thanks to which the leucine threshold is met), adding them will not change a thing.
That is why the use of BCAA is compared to throwing good money after bad. In fact, if we watch the supply of wholesome protein in our diet, the money intended for BCAA could be better spent on another supplement with proven effects, e.g. creatine.
Read also "5 supplements for athletes that don’t deliver what they promise".
If we decide to supplement BCAA, we should dose it reasonably. The standard dose of BCAA is 10 g per day, usually 5 g before and 5 g after the workout, regardless of body mass. With doses around 10 g per day, there is no need to worry about side effects. However, if the dosage is greater, then there is a risk that BCAA amino acids will limit the absorption of other protein amino acids from food.
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References:
- Churchward-Venne T.A., Breen L., Di Donato D.M.et al., Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial. „Am J Clin Nutr.” 99(2), 2014, 276-86.
- Fuchs CJ, Hermans WJ, Holwerda AM (2019) Branched-chain amino acid and branched-chain ketoacid ingestion increases muscle protein synthesis rates in vivo in older adults: a double-blind, randomized trial. Am J Clin Nutr 110:862–872.