science nutrition blog

By: Robert A. Schinetsky

 The supplement industry is filled with various ingredients promising exceptional gains, performance, and recovery. However, only a handful of these ingredients have consistently proven effective in human studies. Among these are creatine, beta-alanine, betaine, and caffeine, which have been staples in supplements for a long time.

Another long-standing supplement in the industry is Glutamine. Once considered essential for muscle building and recovery, it's often promoted for glutamine muscle recovery and glutamine muscle growth. Today, we explore the role of glutamine for muscle recovery and its actual benefits.

What is Glutamine?

 Glutamine is a conditionally essential amino acid. Your body has essential amino acids, which it cannot produce and must obtain from the diet, and nonessential amino acids, which the body can synthesize. Conditionally essential amino acids, like glutamine, are usually adequately supplied by the body but become essential during illness, injury, or extreme stress. Glutamine is the most abundant amino acid in the body, especially in skeletal muscles, making up 61% of your muscle composition.

 Now, conditionally essential amino acids are ones that under normal circumstances, the body has ample supply of; however, in times of illness, injury, or extreme stress, the body can’t synthesize enough to keep up with demand, shifting the amino acid from conditionally essential to essential. Glutamine falls into the category of conditionally essential, as your body usually has more than enough glutamine stored for its needs. In fact, glutamine is the most abundant amino acid in the body, stored all over your body, but especially rich in your skeletal muscles (61% of your muscles consist of glutamine).

What does Glutamine do?

 Glutamine plays several roles in the body. As an amino acid, it's involved in protein construction, leading some to mistakenly label it a "muscle building" supplement. However, the perceived l-glutamine benefits for muscle growth and recovery are often exaggerated.

Glutamine is produced in muscles and distributed via the bloodstream to organs that need it, acting as fuel for cells like lymphocytes and macrophages. This is crucial after severe injury or surgery, where nitrogen from glutamine aids in wound repair and organ function. Glutamine also supports cognitive function, serving as a precursor for neurotransmitters like glutamate, aspartate, and GABA.

 Glutamine is also involved in cognitive function as well, as it serves as the precursor for the excitatory neurotransmitters glutamate and aspartate as well as the inhibitory amino acid, gamma-aminobutyric acid (GABA).

Glutamine for Muscle Growth?

Given glutamine's abundance in muscles and its nitrogen content, it's easy to assume that l-glutamine for muscle recovery or growth is effective. Muscle growth and recovery require a positive nitrogen balance, where nitrogen intake exceeds output. However, scientific evidence does not support the effectiveness of glutamine for these purposes.

During periods of muscle breakdown, nitrogen from glutamine is needed for repair and immune cell support. While supplementing with glutamine seems beneficial in theory, research tells a different story. Studies in healthy individuals show no improvements in recovery, muscle growth, performance, or strength from glutamine supplementation.

 However, when you really start to look at the science of glutamine supplementation, the research tells a very different story. While early studies with glutamine noted that it was useful for burn victims, individuals with stomach ulcers, and muscle-wasting diseases (such as AIDS), those studies by an large administered glutamine intravenously, meaning it was injected directly into the bloodstream.

 However, in otherwise healthy individuals who are looking to use glutamine to enhance recovery and muscle growth, the research tells a very different story. Multiple studies have been conducted and found absolutely no benefit on recovery, muscle growth, athletic performance, or strength from glutamine supplementation.

Exercise Research: Glutamine for Muscle Recovery?

Research involving healthy young adults performing resistance training with glutamine supplementation (0.9g/kg bodyweight) for six weeks concluded no significant effects on muscle performance, body composition, or protein degradation.

 “We conclude that glutamine supplementation during resistance training has no significant effect on muscle performance, body composition or muscle protein degradation in young healthy adults.”

 Another trial assessed whether glutamine could be useful for accelerating muscle repair following eccentric exercise. Researchers found no evidence of a beneficial effect of oral glutamine supplementation on muscle repair following training or muscle soreness, two commonly cited reasons for using glutamine.

 A 2007 research review also concluded:

 “This review examines the effects of glutamine on exercise and demonstrates a lack of evidence for definitive positive ergogenic benefits from glutamine supplementation.”

 And, another 2008 review on glutamine supplements in athletes stated:

 “the majority of studies have found no beneficial effects of maintaining plasma glutamine concentration, with glutamine supplements during exercise and recovery, on various immune responses after exercise.”

 Essentially what these studies are showing is that glutamine supplements do virtually nothing for increasing plasma glutamine concentrations, enhancing recovery, or building muscle. The purported l-glutamine dosage for muscle recovery has not been proven effective in healthy individuals.

 By now, you’re probably wondering why the early studies with glutamine demonstrated it was effective, but when used by the gym bros, it wasn’t.

Glutamine has terrible bioavailability

Early research on glutamine involved critically ill patients receiving glutamine intravenously, directly into the bloodstream. In contrast, athletes taking oral glutamine supplements face bioavailability issues. The stomach, liver, and intestines consume most of the glutamine before it reaches the bloodstream, limiting its availability to muscles.

For those considering glutamine post workout, it's important to understand these bioavailability challenges. While the idea of glutamine for recovery is appealing, the body's absorption limitations make it less effective than anticipated.

 It has incredibly low bioavailability. In other words, when you consume glutamine orally, it’s not taken up very well by the body. This has to do with the fact that the stomach, liver, and intestines LOVE glutamine. They’re greedy, they don’t want to share glutamine. And, when you consume glutamine supplements, the glutamine passes through all of those organs before it has the opportunity to enter your bloodstream and be delivered to your muscles.

 Essentially, those expensive glutamine supplements are gobbled up by your GI system, and never really make it to your muscles.

 And, to further drive home the point, other research indicates that supplementing with glutamine may actually harm you.

Negative Effects of Glutamine

 A 2014 review on ventilated patients found that glutamine supplementation did not reduce muscle protein breakdown and could increase inflammation, potentially accelerating muscle breakdown. Research also suggests that glutamine supplementation can reduce mTOR phosphorylation, hindering muscle growth. Additionally, certain tumors can adapt to use glutamine, posing potential risks.

 Furthermore, that same study noted glutamine supplementation can potentially increase the inflammatory response, and lead to excessive inflammation and complications.

 Other research indicates that glutamine supplementation can actually reduce phosphorylation of mTOR, the exact opposite of what you want when trying to maximize muscle growth.

 As if that wasn’t bad enough, other research indicates that certain tumors can “reprogram” themselves to run on different fuel sources (glucose is their preferred fuel source). Science has identified glutamate (derived from glutamine) can satisfy the glutamine needs of glioblastoma, one of the most aggressive forms of brain cancer.

 Given all the negative research on glutamine supplements, it’s only natural to wonder -- why do supplement companies continue to sell it?

Quite simply, GREED!

 Glutamine is an incredibly cheap ingredient, and a big reason it’s used to “fill out” low quality pre workouts, amino acid supplements, and protein powders. On top of that, supplement companies are hedging their bets that the average consumer doesn’t really know all that much about supplements, and they’re making millions off of the uninformed consumer.

 Advanced Molecular Labs is here to help sort through all the nonsense and deliver the truth about supplements to you, which is why we use only ingredients backed by human research in our supplements.

Takeaway

 At the end of the day, you don’t need to supplement with Glutamine. It’s not an essential amino acid, and can readily be synthesized from other amino acids in the body or obtained from any number of foods you consume on a daily basis, as the BCAAs naturally found in protein serve as precursors of glutamine.

As such, you won’t find any glutamine in either AML Pre Workout or AML Post Workout. We’ve done the research and provide only those supplements proven to deliver real results all in the effort to push your performance, muscle growth, and recovery to the next level, without relying on unproven l-glutamine benefits.

References

1. Castell LM, Poortmans JR, Newsholme EA. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol. 1996;73:488-90.
2. Candow DG, Chilibeck PD, Burke DG, Davison KS, Smith-Palmer T. Effect of glutamine supplementation combined with resistance training in young adults. Eur J Appl Physiol. 2001;86(2):142-149. doi:10.1007/s00421-001-0523-y
3. Albrecht J, Sidoryk-Wegrzynowicz M, Zielinska M, Aschner M. Roles of glutamine in neurotransmission. Neuron Glia Biol. 2010;6(4):263-276. doi:10.1017/S1740925X11000093
4. Parry-Billings M, Evans J, Calder PC, Newsholme EA. Does glutamine contribute to immunosuppression after major burns? Lancet (London, England). 1990;336(8714):523-525.
5. Oudemans-van Straaten HM, van Zanten AR. Glutamine supplementation in the critically ill: friend or foe? Critical Care. 2014;18(3):143. doi:10.1186/cc13879.
6. Elvia S, Valencia H, Sánchez LM, Clark P, Altamirano LM, Mejía M. Glutamina como coadyuvante en la recuperación de la fuerza muscular : revisión sistemática de la literatura. 2015;32(4):1443-1453. doi:10.3305/nh.2015.32.4.9321
7. Gleeson M, Walsh NP, Blannin AK, et al. The effect of severe eccentric exercise-induced muscle damage on plasma elastase, glutamine and zinc concentrations. Eur J Appl Physiol Occup Physiol. 1998;77(6):543-546. doi:10.1007/s004210050373
8. Michael Gleeson; Dosing and Efficacy of Glutamine Supplementation in Human Exercise and Sport Training, The Journal of Nutrition, Volume 138, Issue 10, 1 October 2008, Pages 2045S–2049S, https://doi.org/10.1093/jn/138.10.2045S
9. Deldicque L, Sanchez Canedo C, Horman S, et al. Antagonistic effects of leucine and glutamine on the mTOR pathway in myogenic C2C12 cells. Amino Acids. 2008;35(1):147-155. doi:10.1007/s00726-007-0607-z
10. Krall AS, Christofk HR. Rethinking glutamine addiction. Nat Cell Biol. 2015;17(12):1515-1517. doi:10.1038/ncb3278