Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?

[tarmyg]

I have gotten anyone I help in the gym or otherwise off BCAA as I have found it to be useless. It would seem the scientific data supports my conclusion based on very few people.

REF: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5568273/

Abstract
The branched chain amino acids (BCAAs) are leucine, valine and isoleucine. A multi-million dollar industry of nutritional supplements has grown around the concept that dietary supplements of BCAAs alone produce an anabolic response in humans driven by a stimulation of muscle protein synthesis. In this brief review the theoretical and empirical bases for that claim are discussed. Theoretically, the maximal stimulation of muscle protein synthesis in the post-absorptive state in response to BCAAs alone is the difference between muscle protein breakdown and muscle protein synthesis (about 30% greater than synthesis), because the other EAAs required for synthesis of new protein can only be derived from muscle protein breakdown. Realistically, a maximal increase in muscle protein synthesis of 30% is an over-estimate because the obligatory oxidation of EAAs can never be completely suppressed. An extensive search of the literature has revealed no studies in human subjects in which the response of muscle protein synthesis to orally-ingested BCAAs alone was quantified, and only two studies in which the effect of intravenously infused BCAAs alone was assessed. Both of these intravenous infusion studies found that BCAAs decreased muscle protein synthesis as well as protein breakdown, meaning a decrease in muscle protein turnover. The catabolic state in which the rate of muscle protein breakdown exceeded the rate of muscle protein synthesis persisted during BCAA infusion. We conclude that the claim that consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted.

Conclusion
A physiologically-significant increase in the rate of muscle protein synthesis requires adequate availability of all amino acid precursors. The source of EAAs for muscle protein synthesis in the post-absorptive state is the free intracellular pool. Intracellular free EAAs that are available for incorporation into protein are derived from muscle protein breakdown. Under normal conditions about 70% of EAAs released by muscle protein breakdown are reincorporated into muscle protein. The efficiency of reincorporation of EAAs from protein breakdown back into muscle protein can only be increased to a limited extent. For this fundamental reason, a dietary supplement of BCAAs alone cannot support an increased rate of muscle protein synthesis. The availability of the other EAAs will rapidly become rate limiting for accelerated protein synthesis. Consistent with this perspective, the few studies in human subjects have reported decreases, rather than increases, in muscle protein synthesis after intake of BCAAs. We conclude that dietary BCAA supplements alone do not promote muscle anabolism.

[MuscleScience]

I have gotten anyone I help in the gym or otherwise off BCAA as I have found it to be useless. It would seem the scientific data supports my conclusion based on very few people.

REF: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5568273/

Abstract
The branched chain amino acids (BCAAs) are leucine, valine and isoleucine. A multi-million dollar industry of nutritional supplements has grown around the concept that dietary supplements of BCAAs alone produce an anabolic response in humans driven by a stimulation of muscle protein synthesis. In this brief review the theoretical and empirical bases for that claim are discussed. Theoretically, the maximal stimulation of muscle protein synthesis in the post-absorptive state in response to BCAAs alone is the difference between muscle protein breakdown and muscle protein synthesis (about 30% greater than synthesis), because the other EAAs required for synthesis of new protein can only be derived from muscle protein breakdown. Realistically, a maximal increase in muscle protein synthesis of 30% is an over-estimate because the obligatory oxidation of EAAs can never be completely suppressed. An extensive search of the literature has revealed no studies in human subjects in which the response of muscle protein synthesis to orally-ingested BCAAs alone was quantified, and only two studies in which the effect of intravenously infused BCAAs alone was assessed. Both of these intravenous infusion studies found that BCAAs decreased muscle protein synthesis as well as protein breakdown, meaning a decrease in muscle protein turnover. The catabolic state in which the rate of muscle protein breakdown exceeded the rate of muscle protein synthesis persisted during BCAA infusion. We conclude that the claim that consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted.

Conclusion
A physiologically-significant increase in the rate of muscle protein synthesis requires adequate availability of all amino acid precursors. The source of EAAs for muscle protein synthesis in the post-absorptive state is the free intracellular pool. Intracellular free EAAs that are available for incorporation into protein are derived from muscle protein breakdown. Under normal conditions about 70% of EAAs released by muscle protein breakdown are reincorporated into muscle protein. The efficiency of reincorporation of EAAs from protein breakdown back into muscle protein can only be increased to a limited extent. For this fundamental reason, a dietary supplement of BCAAs alone cannot support an increased rate of muscle protein synthesis. The availability of the other EAAs will rapidly become rate limiting for accelerated protein synthesis. Consistent with this perspective, the few studies in human subjects have reported decreases, rather than increases, in muscle protein synthesis after intake of BCAAs. We conclude that dietary BCAA supplements alone do not promote muscle anabolism.

Totally agree, BCAA’s was just a way to take what is already in a cheaper product (whey) and make it a value added supplement.

[Clove1234]

Definately think its a scam, and i feel like most people don’t realize that you also need to be ingesting EAA’s as well.

[Gallowmere]

I’m glad to see that more and more research is finally showing just how pointless BCAAs are for most people.

About the only ones I could see getting any use out of them are vegans, using them in addition to their normal protein meals as a means to properly spike MPS.

[CMB]

Hey guys, what's up?

Look, I don't use BCAAs but I have in the past. It has been too long so I cannot comment on the efficacy of my past usage other than they didn't do anything crazy.

This one study, which is interesting, only proposes one mechanism of action that doesn't support BCAAs. So let's not jump to concrete conclusions.

Nevertheless, there is a great deal of information which supports the usage of BCAAs for athletes. There are CERTAIN times that BCAAs are useful IMO. Pre/intra workout are two times that come to my mind right away, but there are others too.

A good point has been raised in this thread though, whey protein provides an abundnace of said BCAAs and proobably render further supplementation unnecessary.

Just my .02

[CMB]

Also, amino acids that are not in whole-protein form (aka supplementing l-leucine, alaine, etc) has been shown to cause cancer. This is according to a human nutrition textbook.

[Gallowmere]

Hey guys, what's up?

Look, I don't use BCAAs but I have in the past. It has been too long so I cannot comment on the efficacy of my past usage other than they didn't do anything crazy.

This one study, which is interesting, only proposes one mechanism of action that doesn't support BCAAs. So let's not jump to concrete conclusions.

Nevertheless, there is a great deal of information which supports the usage of BCAAs for athletes. There are CERTAIN times that BCAAs are useful IMO. Pre/intra workout are two times that come to my mind right away, but there are others too.

A good point has been raised in this thread though, whey protein provides an abundnace of said BCAAs and proobably render further supplementation unnecessary.

Just my .02

This is actually just one example among many. Alan Aragon has compiled a pretty big list of studies showing their uselessness, especially when comparing cost to benefit. I’ll see if I can dig up his list.

[CMB]

This is actually just one example among many. Alan Aragon has compiled a pretty big list of studies showing their uselessness, especially when comparing cost to benefit. I’ll see if I can dig up his list.

That would be useful if you can find it.

Yes, I believe BCAAs can be useful... provided they are used at appropriate ratios and the correct times!

Nevertheless, I won't use them. The only amino acid I consume is beta-alinine... that is an ingredient in my preworkout, and I wish it wasn't there to be frank.

Always remember, the body is built to consume whole proteins and break them down to amino acids. Never ever in our DNA were we supposed to consume amino acids individually. This is what can cause cancer from amino acid supplementation, though more research is needed to verify the extent of this....

[tarmyg]

This is not "one" study. It is a meta-analysis of all existing studies so any more accurate material on this subject do not exist.

[CMB]

This is not "one" study. It is a meta-analysis of all existing studies so any more accurate material on this subject do not exist.

Apologies, you're correct it is a meta-analysis. I did a brief read on the article.

Nevertheless, I could pull conflicting studies which would just muddy the waters further.

My point being, this is a good article - though it doesn't (IMO) by itself lead me to the conclusion that BCAAs are never effective.

[tarmyg]

Apologies, you're correct it is a meta-analysis. I did a brief read on the article.

Nevertheless, I could pull conflicting studies which would just muddy the waters further.

My point being, this is a good article - though it doesn't (IMO) by itself lead me to the conclusion that BCAAs are never effective.

Actually, that is the conclusion. You can not point to other single studies when someone does a meta-analysis as those would be negated. What exactly is your scientific argument against this comprehensive analysis? You have sort of peeked my interest now.

[CMB]

This will be my last post in this thread.

The idea behind BCAA supplementation is to help retain a positive nitrogen balance and replace used BCAAs lost through exercise. This, in theory, promotes an anabolic environment as well as enhancing performance.

On a side note, I don't enjoy pulling up conflicting evidence on issues similar to these as we can go back and forth all day finding studies that both support and disprove certain supplements. Indeed, supplement studies are notoriously all over the spectrum which just makes the truth unclear.

The link I provided is a study pertaining to bodybuilding and relevant to this board

https://www.nutritionexpress.com/art...icle.aspx?id=7

Cheers!

[tarmyg]

This will be my last post in this thread.

The idea behind BCAA supplementation is to help retain a positive nitrogen balance and replace used BCAAs lost through exercise. This, in theory, promotes an anabolic environment as well as enhancing performance.

On a side note, I don't enjoy pulling up conflicting evidence on issues similar to these as we can go back and forth all day finding studies that both support and disprove certain supplements. Indeed, supplement studies are notoriously all over the spectrum which just makes the truth unclear.

The link I provided is a study pertaining to bodybuilding and relevant to this board

https://www.nutritionexpress.com/art...icle.aspx?id=7

Cheers!

That is not a study but an article written at, out of all places, a place selling supplements. I mean, really? The idea as you wrote above has been shown to not hold much water. It can of course not be proven wrong as that is impossible but all evidence at this time points to it not being helpful.