Every once and a while a supplement seems to take over the fitness industry. It becomes the hot topic amongst every gym goer on the planet, while simultaneously becoming the primary interest of every exercise scientist around the globe.
Which is what happened a couple of years ago to Glutamine.
But is it really it's all cracked up to be, or is it just another overhyped supplement that is costing you money?
What is Glutamine?
Glutamine is one of the 20 amino acids your body needs to survive.
Although amino acids play a number of important roles in your body, they are arguably most well known because they are used to produce proteins. These little compounds are used to create every protein in your body, which means that they ultimately act as the building block for your cells.
And of course this includes your muscle cells, as well as the cells that make up your bones, organs, skins, hair, and practically anything else you can think of.
In short, they are very important -- and none more so than glutamine.
Glutamine is the most abundant amino acid in your body. The vast majority of it is found within your muscle tissue. This indicates that it plays an important role in the production and development of new muscle tissue, which also explains its popularity as a supplement.
I should note that the form of glutamine found in your body is called “L-glutamine”, and it can actually be made by your body. However, there are times when the amount of glutamine made in your body is insufficient to meet its demands -- which is thought to impair function.
All of which should give you some insight into why supplementing with glutamine might be such a good idea.
What are the Benefits of Glutamine?
So, we know that glutamine has a number of important roles in the human body, particularly when it comes to muscle cell function -- but how does its supplementation benefit you?
Glutamine and Recovery
When it comes to gaining size, your ability to recover is integral.
I mean, I am sure you have heard it all before.
Training in the gym is what breaks down your muscle tissue, and tells your body that it needs to rebuild itself bigger and stronger -- a process that can only occur if you recover appropriately.
While this is a rather simple way of looking at things, it is very much true.
Now, the supplementation of glutamine has been shown to speed up recovery after intense bouts of resistance exercise. It has also been shown to lead to reductions in muscle soreness after training compared to not taking glutamine [1].
This means that it can facilitate your ability to repeatedly show up and train at the gym -- which is key to making long term, injury free, progress.
Glutamine and Immunity
Although most of the glutamine in your body is found within muscle tissue, it also has a very important function with respect to your immune system.
In short, glutamine is used for energy by your immune cells.
As a result, it has the ability to improve your recovery after things like major injuries. It has also been shown to boost immunity and reduce your likelihood of getting an infection, while also helping your body fight off invading bacteria and viruses [2].
While this may not sound as flashy as improved recovery, I would argue that it is even more important.
I mean, there is no doubt in my mind that the most important predictor of training success is your ability to actually get in the gym and train. And very simply, you cannot train if you are sick.
With this in mind, glutamine might be able to keep you consistent in the gym, which is essential to making gains.
Glutamine and Gut Health
Finally, glutamine has also been shown to improve digestive health -- especially in people who are in a high state of stress.
Like your immune cells, glutamine is also used as a fuel source for many of the healthy bacteria that live in your gut. As such, it can help maintain the barrier between your intestines and the rest of your body, aiding in digestion [3].
Interestingly, this has been suggested to improve the uptake of protein from the digestive tract in people who are highly stressed (stress has been shown to impair gut function).
So, if you are someone who suffers from a rather stressful lifestyle, or are currently in a high-stress state, glutamine could be a very useful addition to your weekly regime.
Does Glutamine Improve Muscle Growth?
Now, something that I want to note here is that the supplementation of glutamine alone does not appear to improve muscle growth -- or at least in the one study that has explored it in depth.
In this study, people were allocated to two groups. One group underwent a 6 week gym training program while taking a glutamine supplement every day, while the other group did the same training program but took a placebo.
And at the end of the 6 weeks, both groups saw the exact same increases in muscle size [4].
This most likely comes down to the fact that if you are eating enough protein on a daily basis (~1.6 grams per kg of bodyweight), you are maximizing your potential for muscle growth from a dietary standpoint -- somewhat blunting glutamine's effectiveness in this area.
This does not mean that glutamine supplementation is useless, just that it becomes a little less effective if you are eating adequate protein.
Is Glutamine Safe?
Because glutamine is produced by your body, and also found in a number of common foods within a regular diet (albeit in small amounts), there is no reason to believe that it will be harmful in what we could consider “normal” amounts.
What is a normal amount?
Well, it has been estimated that someone eating a typical western diet will consume between 3 and 6 grams of glutamine per day, although this is going to be a little less if you follow a vegan or vegetarian way of eating.
Some research has looked at people taking up to 14 grams per day without any notable side effects, suggesting that this would be a safe upper limit for the vast majority of the population over a 4-10 week period [5].
I do also want to point out that the effects of long term glutamine supplementation have not been explored. Some people believe that adding glutamine supplements to a regular diet may impair your body's ability to absorb glutamine from the food you eat.
As such, making sure that you take some time to cycle off glutamine supplements every 10 weeks would offer a way to mitigate this risk. And of course, make sure you seek advice from a medical professional before supplementation -- just in case.
We would also encourage you to start with a lower dosage (3-5 grams per day) to gauge how your body responds to it. If you do not experience any negative side effects, you can then increase the dosage slowly over time.
Key Points
So, should you be taking glutamine? Like most things in the health and fitness industry, it depends.
Glutamine has been shown to improve recovery after exercise, while also enhancing immune system function. Moreover, it can promote nutrient absorption in people who are currently in a high stressed state -- all of which may improve long term training outcomes.
This makes it the perfect option if you feel your recovery is slower than it should be, or if you are currently stressed out.
However, it will not have huge effects on muscle growth if your diet is on point and you are eating enough protein on a daily basis. While this does not negatively impact its other effects, it does need to be considered.
References
- Legault, Zachary, Nicholas Bagnall, and Derek S. Kimmerly. "The influence of oral L-glutamine supplementation on muscle strength recovery and soreness following unilateral knee extension eccentric exercise." International journal of sport nutrition and exercise metabolism 25.5 (2015): 417-426.
- Cruzat, Vinicius, et al. "Glutamine: metabolism and immune function, supplementation and clinical translation." Nutrients 10.11 (2018): 1564.
- Camilleri, Michael, et al. "Intestinal barrier function in health and gastrointestinal disease." Neurogastroenterology & Motility 24.6 (2012): 503-512.
- Candow, Darren G., et al. "Effect of glutamine supplementation combined with resistance training in young adults." European journal of applied physiology 86.2 (2001): 142-149.
- Shao, Andrew, and John N. Hathcock. "Risk assessment for the amino acids taurine, L-glutamine and L-arginine." Regulatory toxicology and pharmacology 50.3 (2008): 376-399.
