Study: “BCAA use unnecessary”

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BCAAs

BCAAs are often promoted to prevent muscle breakdown based on non-representative research. This has led to BCAAs being overvalued.

In this first part of a series of three articles, I will provide an introduction where I compare BCAAs with other amino acids, among other things. What makes these three amino acids, leucine, valine, and isoleucine, so special? In the second part, I will attempt to answer the question of whether it makes sense to take BCAAs when you already consume protein around your workout. Finally, in the third part, I will compare BCAAs and discuss their use during the “cutting phase,” when you try to burn body fat while maintaining as much muscle mass as possible.

BCAAs

If you want to write an article about BCAAs, you can approach it positively or negatively and find dozens of studies to support both views. I’m not talking about texts and studies from the manufacturers themselves, but independent, objective, and scientific studies that contradict each other. I could have made it very easy for myself and written a short piece about BCAAs, stating that they limit muscle breakdown. However, there are already dozens of websites that do that. Unjustifiably, in my humble opinion, because the vast majority of the studies referenced (if referenced at all) are not actually relevant. The studies that are relevant show different results.

Although I try to keep articles somewhat concise and understandable, that seems impossible for this topic due to the large number of often contradictory studies.

Correct Approach to Evaluating BCAAs

The amino acids leucine, isoleucine, and valine are the so-called Branched Chain Amino Acids (BCAAs). These amino acids play a special role in regulating muscle growth. However, one may wonder why intake of precisely these three amino acids can offer an advantage in addition to protein intake, which contains all twenty amino acids. Most studies do not assume a situation in which someone eats enough carbohydrates, fats, and especially protein, and are therefore wrongly used to promote BCAAs as they are not representative.

In this article, I address two possible advantages that BCAAs offer compared to complete protein. Since a lot has already been written about BCAAs on Fitsociety, I will mainly focus on the added value compared to a good diet including sufficient protein. This seems a more logical starting point since most (informed) strength athletes have protein at number one on the list of supplements. Additionally, I will compare BCAAs with other amino acids, both essential and non-essential.

Why BCAAs for Muscle Mass?

During the Bodypower Expo in Birmingham, I asked four-time Mr. Olympia Jay Cutler which supplements he would choose if he could only pick two:

Kenneth: “It can be very difficult for people to choose from the wide range of supplements. If you could choose two supplements as favorites, which ones would they be… aside from the brand, because I understand that you naturally go for BPI” (ed. Given that Jay’s supplement line is marketed by BPI.)

Jay: “Haha, of course. First of all, a good protein, that’s really the basis when it comes to supplements. Secondly, I would say BCAAs before and during training.”

Amino acids in general are important for building protein in the muscles, which creates muscle mass. The muscles use the free, readily available amino acids for this purpose. The amino acids become available on the one hand through protein in food that is broken down into free amino acids during metabolism. On the other hand, they become available through the breakdown of existing protein in the muscles [1]. The extent to which your muscles grow depends on this balance between the breakdown of current protein and the production of new protein using available amino acids from food [1,2,3]. Strength training increases the production of new protein (“protein synthesis”) for 24-48 hours. However, at the same time, breakdown also increases [4,5,6]. Ultimately, food determines which way the balance tips [7,8,9]. BCAAs play a special role in this [9].

BCAAs (leucine, isoleucine, and valine), particularly leucine, have anabolic effects on protein metabolism by increasing the rate of protein synthesis and decreasing the rate of protein degradation in resting human muscle.

E. Blomstrand, Åstrand Laboratory, University College of Physical Education and Sports [10]

They are required specifically for the synthesis of proteins, not as precursors of unique biologically active molecules. The BCAA comprise about 35% of the indispensable amino acids in muscle proteins and about 40% of the amino acids required preformed by mammals.

A.E. Harper, University of Wisconsin [11]

BCAAs thus constitute 35% of the essential amino acids in muscles [11]. I emphasize ‘essential’ because various media claim that it concerns 35% of all amino acids. This may be related to commerce. If you say that three of the twenty amino acids (15%) account for 35% of the amino acids in muscles, it sounds more impressive than if it concerns 35% of the nine essential amino acids present. However, that does not mean that BCAAs do not stand out from other amino acids, both essential and non-essential.

The most important point here is that BCAAs thus (would) contribute to more muscle mass by limiting the breakdown of protein in the muscles [9,12,13].

Bioavailability: How Much of the Ingested Amino Acids Can Be Used by the Muscles?

Where many amino acids are needed for certain biological processes, such as conversion into other substances, BCAAs are primarily building blocks for proteins synthesized in the muscles. They stand out from all other amino acids due to their chemical structure and the way they are processed using the enzymes BCAA aminotransferase, Branched-chain ketoacid dehydrogenase, and acyl CoA dehydrogenase [11].

Multiple sources mention that BCAAs do not need to undergo the “first pass” through the liver like other amino acids. This first pass causes other amino acids to be processed first,

broken down, and/or converted into other substances. This delays their availability in the blood and they arrive there in smaller quantities. Although BCAAs are spared this time, it does not mean that they end up completely in the muscles.

There is more in the nine meters between mouth and anus [14] that affects the “bioavailability” (the amount of a substance that actually reaches the intended destination). Think of the stomach itself and the intestines. Various studies in humans and animals have shown that BCAAs are also consumed in this process and do not end up entirely in the muscles [15-21].

Researchers from the University of Alberta studied the need for BCAAs in newborn babies [22]. To determine what a good dose would be, they wanted to know how much of the ingested amino acids actually reached the bloodstream and were therefore available for the muscles. By giving the same amount of BCAAs to pigs both intravenously and orally, they could calculate the difference. When eaten, 44% of the BCAAs were found not to reach the bloodstream.

Using breakpoint analysis, the mean total BCAA requirements were determined to be 1.53 and 2.64 g/(kg. d) for parenterally and enterally fed piglets, respectively. Thus, the parenteral requirement for total BCAA is 56% of the enteral requirement, suggesting that 44% of total BCAA is extracted by first-pass splanchnic metabolism.

R. Elango, University of Alberta

However, this does not mean that this 44% is primarily used as building blocks for the muscles, whereas the other amino acids are used for numerous other processes.

Summary

BCAAs play a special role compared to other amino acids, especially regarding muscle growth.

BCAAs are not broken down, used, or converted in the liver like other amino acids. However, this does not mean that they end up completely in the muscles as sometimes claimed. Ultimately, about 44% is used as building blocks for the muscles.

Part II: BCAAs and Protein?

In the next part, I compare the use of protein with BCAAs. For example, how many BCAAs do you get if you take 30 grams of whey or other protein after your workout? What does separate intake of BCAAs add to this?

Here, I not only look at the amounts of amino acids in both forms (whole protein vs. loose BCAAs), but I also discuss the different speeds at which they are absorbed into the bloodstream after ingestion.

However, the most important aspect is the treatment of studies that have examined whether the intake of loose BCAAs adds to muscle growth when “sufficient” protein is already being consumed.

References

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