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Fact checked by Andrew Lenau, ISSA CPT & Sports NutritionistFACT CHECKED
April 04, 2022
For this supplement comparison, we're putting branch-chained amino acids, also known as BCAAs, up against glutamine. These are two of the most popular supplements on the market and also two of the most misunderstood. Will glutamine help muscle growth? Will BCAAs let you workout longer? These are just a couple questions that trainees have about these powders and we think they deserve an answer.
In this article, we'll go over:
Before we ever talk about supplements, at SET FOR SET, we always like to clarify that supplements sit at about #5 for things to worry about with your training. We love ergogenic aids and the science behind them, but we also like to keep them in check. If you are wondering if BCAA or glutamine is better, we will assume that your programming, nutrition, recovery, and sleep are all in check. If so, carry on. If not, still carry on because learning is always good. However, we would highly recommend you get these in check first. While BCAAs and glutamine might be able to improve your performance, it's nowhere near as effective as quality sleep or proper programming. Now that's over, let's talk about BCAA vs glutamine.
BCAAs and glutamine are both some of the most popular sports supplements on the market today. In fact, it's fair to say that the vast majority of lifters or athletes who have ever bought workout supplements have consumed both of these before in the past so let’s talk about what they are.
To start, many people don't understand that both are actually isolated amino acids taken from whole protein. In other words, if you are eating protein, you are already eating BCAAs and glutamine. That being said, they serve very different functions, and one does tend to be better than the other.
But first, let's first clarify what amino acids are. This will be important to know when comparing BCAA and glutamine as we will better understand their roles in human performance and use as an ergogenic aid.
Amino acids are protein, and protein is amino acids. Make sense? Ok, we’ll break it down a little more.
When we use the word "protein”, we are actually referring to a long sequence of amino acids, similar to how several amino acids joined together are called a “peptide.” In this sense, “protein” is really just nomenclature to explain how many amino acids are present, which is generally a sequence of 50 or more amino acids.
This sequence can consist of up to 21 different amino acids, which are further broken down into 3 categories:
As it's so hyped up for being so effective, it may surprise you to learn that glutamine is actually a conditionally essential amino acid. Again, this means that your body can produce sufficient amounts under normal circumstances and there’s no need to consume any from your diet. Interestingly enough, glutamine is actually the most abundant amino acid in the body and accounts for 50-60% of free amino acid!
When it comes to BCAAs, they are actually considered essential amino acids as you must consume these from your diet as your body can not synthesize them. In this aspect, it would seem that exogenous BCAAs are more important merely because your body can only get them from the diet.
Regardless, now let's take a closer look at their actual physiological function in the body.
As mentioned above, glutamine is the most abundant amino acid in the human body. However, its abundance is because it's involved in so many physiological processes that this amount is necessary. In relation to weight training, it has been reported to:
...and that's not even the entire list of supposed benefits. Out of all of these, the most common reason weight lifters will take glutamine is due to its role in muscle recovery. It's often suggested that glutamine can help reduce muscle soreness and improve muscle recovery which ultimately leads to more volume being able to be performed resulting in greater muscle growth.
Here's where things get conflated. What do you mean when you say, "Does glutamine work?". In reality, glutamine actually does play a role in numerous critical physiological processes, even with processes related to muscle building. So in that sense, yes, glutamine works.
However, we want to know if supplementing with glutamine works. Are you going to see benefits by going to a store and spending money on another powder? While this may disappoint many people, if you have been buying glutamine, you have likely just been wasting money.
The best way to describe supplementing with glutamine is "More does not mean better." Just because glutamine is an essential amino acid that plays a vital part in numerous processes does not mean that you should take even more. However, we should mention that this assumes you are already eating adequate protein. Remember that glutamine is already in protein, so in reality, you are already supplementing with glutamine; you just don't need to take it as a solitary ingredient.
Besides, you need to remember that glutamine is the most abundant amino acid in the body by far; it represents 50-60% of all the free amino acids(1). That's a lot of glutamine. However, it’s also a conditionally essential amino acid which should make you question if you really need it anymore as your body seems to be able to get plenty without supplementation.
While some studies may show some benefit, there are a lot more that have shown no benefit. A recent meta-analysis from 2019 looked at a total of 72 studies and clinical trials on glutamine and athletic performance and fitness. Unfortunately, they found no relationship between glutamine and athletic performance. However, interestingly enough, they did note that individuals who took glutamine had more significant weight reduction(2). While this definitely shouldn't be ignored, the vast majority of people who take glutamine are not doing it for weight loss.
This isn't the only meta-analysis to show this. In 2008, yet another large review examined studies on glutamine and sports training. They also found that while glutamine is an important amino acid, there is little to no evidence that it benefits training and fitness(3). In fact, they note that at the time, there were limited studies done with appropriate variables (i.e. using sick adults rather than healthy adults). However, companies were still making similar bombastic claims we see today. Unfortunately, glutamine seems to be another victim of a common trick seen in the fitness industry; the truth is taken out of context, and studies are used incorrectly to hype up a product.
BCAAs get their name due to their structure as one of their chains has a branch attached. Therefore, BCAA stands for Branch Chained Amino Acids. Your BCAAs are actually composed of three different amino acids including:
Mentioned above, all three are classified as essential, which means that ⅓ of your essential amino acids are composed of BCAAs. At the same time, these 3 account for nearly half of the total quantity of BCAAS.
Remember that we have briefly discussed how protein comprises different amino acids and different amino acids have specific duties or functions. BCAAs are so important because these three amino acids play the most vital role in protein synthesis and muscle repair, specifically leucine. Leucine is definitely the most important as its role is to signal mTOR(4), which is in charge of protein synthesis and cell growth; basically, it's the first domino that drops before a complex chain of events occurs.
Due to this pivotal role, BCAAs in athletics and weight training have become very popular.
Meh. While there is better evidence for BCAA than glutamine, it's still not nearly as straightforward as you'd think. Again, the problem is that companies will take a study that shows what they want and just use that while neglecting all the other studies that show the contrary. Or, they may completely leave out important information that totally alters the perception of the outcome.
For example, a huge review just published in 2021 specifically looked at all the literature on BCAA supplementation for strength and hypertrophy. They concluded that, generally speaking, research does not show the efficacy of BCAA for the benefits claimed by supplement companies(5). In fact, they specifically mention this aspect; that marketing claims are at odds with research. However, they note that there are certain circumstances when taking BCAAs may be of benefit, such as in individuals consuming low calories or in the elderly population.
However, another meta-analysis from 2019 concluded that, in fact, BCAAs might be able to improve performance as they "led to a favorable effect on fatigue substances, energy metabolites, and muscle soreness substances"(6). And yet another from 2019 showed that BCAA can help reduce DOMS, yet this is when compared to a placebo(7).
The bottom line is that BCAA may be able to help, especially during times of caloric deficit or strenuous exercise (this does not mean a 45-minute session). However, if you are consuming enough protein, it likely won't help improve muscle hypertrophy or strength gains. If you are eating enough protein, the only situation where you might want to try BCAAs is during an extra-long or extra strenuous workout session. In this case, check out our post that covers the Best BCAA Supplements on the market.
After looking at all of the information above, the answer to glutamine vs. BCAA should be relatively clear. While both are vital compounds for your body to function properly, only one of them might be effective as an exogenous supplement. And that would be your BCAAs.
There is just far too little evidence to suggest any athlete or weightlifter take glutamine. After looking at the studies on glutamine supplementation, the evidence is "unclear" at the very best while "waste of money" is likely a more accurate conclusion. However, the evidence surrounding BCAAs is a bit more compelling and could serve some purpose.
In fact, this is exactly how the International Society of Sports Nutrition (ISSN) has these supplements classified. The ISSN reviews every sports supplement and classifies it with one of three labels(8):
While glutamine is given the low class of "little to no evidence', BCCAs are awarded the "limited or mixed evidence". Still not even that great, but if you had to choose one of the two, BCAAs are the way to go.
However, there is a third option better than BCAAs. Rather than just eat three of the nine essential amino acids, you should just eat all nine! EEAs are quickly becoming the preferred amino acid supplement to take, thanks to more interest and research surrounding this topic. In fact, going back to ISSNs classification system, EAAs are one of the few supplements to be given the top "strong evidence to support efficacy" classification. This means it shares the same rank as creatine and HMB (not that we're saying it's better than creatine as creatine is still the best!)
We can't give a full breakdown here, but basically. At the same time, BCAAs are the most important amino acids regarding muscle protein synthesis, the other amino acids still play a role, and the effect is buffered without them. Therefore, whenever anyone asks about BCAAs, we suggest they get some EAAs instead - Check out this article for a more in-depth comparison of EAAs vs BCAAs.
While BCAAs and glutamine are some of the most popular supplements on the market, unfortunately, neither are really that great for athletic performance, especially glutamine. While technically, BCAAs are the superior supplement, you really should just do yourself a favor and buy some EAAs. Realize that we aren't suggesting a completely different supplement with a different function, like when you ask if you should buy a truck or SUV and someone says you should buy a bike. EAAs do exactly what you think BCAAs do, just better.
Even still, we only suggest EAAs if all of your other variables are in check.
Now you can start to worry about supplements. Enjoy!
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