Glutamine: The Best Post-Workout Supplement

You would often get a variety of answers from people, if you asked them what their thoughts on glutamine are. Those answers range from something like “Worked like a charm”, to “I felt no difference at all”. So, which is it? Does it really work or not? In this post, we’ll go in detail in explaining what glutamine is exactly, exploring the various phases at which it helps to improve muscle recovery and then look into the latest scientific arguments, leading us to the final question: Should you start using glutamine as a supplement in your diet?


First things first.What Is It?

Glutamine is an amino acid that is naturally found in your body and it is the most abundant. It is one of a group of 20 amino acids that are non-essential. What this basically means is that the body can “construct” glutamine on its own from already available compounds in your body whenever it deems necessary. You can satisfy your body’s need for glutamine by eating quality protein-rich diet, such as fish, steak, dairy products, poultry and beans. But the fast that I belongs to the non-essential group of amino acids, doesn’t mean you should disregard taking it as a supplement. The reason being is that glutamine is the primary fuel source boosting your immunity and a big part of it is stored within your muscles.

Evidence has shown that intense workouts force your muscles to release glutamine into the bloodstream, depleting your reserves of glutamine by almost half of the total amount. Such a depletion can start the wasting or breaking down of muscle tissue. It seems that the depletion of glutamine is mostly influenced on how intensive the workout challenge was. In its most extreme cases, catabolic circumstances experienced by burn patients can have depletion effect by as much as 90%, whereas a recreational lifter would have a negligible drop in glutamine levels. In the middle, you would find serious athletes, who would usually use their glutamine within the 30-50% range. So, the conclusion drawn here could be that the greater your workout effort is, the more glutamine you use, leading many experts to think of glutamine as an optional non-essential amino acid.


How does it work?

Glutamine has many roles within your body. It helps with muscle metabolism and recovery, as well as supporting your immune system. It has also proven itself a great multi-tasker since it does not get stored the same way fat or cards are, into adipose tissue or glycogen reserves in the muscles, respectively. On the contrary, it becomes whatever is needed of it, and mostly it is needed for the purpose of building and maintaining muscle tissue.

Its form is always transient, meaning it keeps changing all the time. At one time, it can constitute a part of a cell membrane, at some other time, it can be a part of a hormone or an enzyme, whatever the body “asks” of it, and its levels will rise or fall based on your body’s daily needs. This ties in perfectly into what we discussed about glutamine depletion after your workour hindering your results because of its effect on the muscle response and immune system.

There are for ways in which research has proven glutamine to help increase recovery: It is always readily available, ensuring muscle breakdown does not occur and prevents muscle tissue being used by your body, which is something that is known as “protein sparing” in bodybuilding circles. The way it spares protein is by signaling the formation of glycogen, which in turn, is derived from carbohydrate breakdown and is the number one choice of energy source of your body when it comes to exercise. When the glycogen reserves are diminished, your body turns to your muscle tissue as a secondary energy source and wants the protein available in there. That’s something a smart lifter would want to avoid. When glycogen levels are extremely depleted, glutamine directly stimulates the activity of an enzyme, that is charge of creating glycogen in liver and muscle cells.

A study that was done on cyclists, used glutamine as a fuel source for the athletes during a two-hour workout. The ingestion of glutamine resulted in doubling the glycogen reserves in muscles. It has also been proven to be essential for hydration of the cells, which helps them maintain their volume, which again increases protein synthesis, the rebuilding and repairing of muscle tissues. The logic is the following: Glutamine enters the cell, attracts water into it and gives it volume. The end result is a hydrated cell which is harder to be broken down, thus helping you maintain your muscle mass.

The way it protects the immune system is by being the number one energy source for the immune cells, which in turn helps you build more muscle. If the immune cells themselves lack glutamine to make the necessary repairs, they will find another source in another place.Since we already concluded that the body’s reserves of glutamine are found in your muscles, then your muscles will be the first thing being broken down when the immune system is in search of fuel. Another way in which glutamine helps your training is by boosting your immune system to fight off any infections which can sideline your training and make you weaker.  Considering its close correlation with the immune system, supplementing with glutamine has proven effective in the treatment of burn patients, cancer and HIV/AIDS.

Bad or good?

The same question is often posed about all supplements as to whether they are really needed for active people. The same goes for glutamine and the answer isn’t always straightforward. Some think that supplementing with such a readily available substance is not necessarily needed for a normal athlete, and so far firm evidence to support supplementing with glutamine is fairly lacking. Some simply that following the traditional post-workout meal protocol of simple carbs and whey protein is more efficient than relying on a single amino acid. Several studies support this. There was one study done, where elite wrestlers were given glutamine with the aim of preserving muscle mass while on a cutting diet, and no evident differences were seen between those using glutamine and those who weren’t. Another study also gave no positive results when athletes were supplementing with additional glutamine doses in the hopes it would help in the prevention of suppressing the immune system post-workout.

Several reasons why most of these studies failed to provide positive results might be due to the fact that they were poorly designed and executed. Many of them observe a small number of participants, they give them capsules with questionable quality and a sample training program and in the end aren’t very diligent in fully managing either the supplements or the participants. What this means is that the participants sometimes forget to take the pills or miss a few of their workouts, which would usually give a “false negative”. One must also take into consideration that the workouts the participants did, might not have been intensive enough.

There seems to be a workout intensity threshold over which glutamine can be used for retaining muscle and increase recovery rates, meaning you would need to work very hard in the gym, in order for it to bring any results, otherwise it might not add much to your overall progress. But if you do, results will soon follow. Let’s recall that glutamine is used by your immune system as its main energy source. That way, if you work hard in the gym and cause extensive muscle damage, your immune cells would also have to increase their activity. Another way to look at it is this one: If you work your biceps on a given training session, the body would need to repair that particular muscle. What happens next is that the immune system will start getting glutamine from other muscles, like your abs, thighs or shoulders, if your overall glutamine reserves are low, in order to repair the damage done to the biceps. If we keep this into consideration, then adding glutamine to your post-workout meal or shake could really increase muscle recovery and repair, stopping the breakdown or catabolism of muscle tissue as a result of a hard training session.

Who can benefit?

If we define glutamine as “optionally essential”, meaning your body’s need for it increases when you are under stress, after a heavy workout, illness or an injury, then one begs the question: who can really benefit from its use? According to experts, the following two groups:

1. Bodybuilders or physique competitors. Dieting for a show, like getting you body fat level to a single digit can be really stressful for your body, as well as deplete your protein and glutamine stores. Catabolism may increase dramatically if the immune system isn’t capable of stopping it, when you are in the process of continuous training. Another benefit that may appeal to many athletes is that glutamine can lower your cravings for sugar. A low dose of 1.500 mg between your daily meals can make a huge difference when you are following a cutting diet plan.

2. Endurance athletes. It’s been found that distance runners have a greater chance of catching a cold or other respiratory infections than an average bodybuilder. This suppression of the immune system makes these athletes the perfect candidates for glutamine supplementation.


The general consensus among nutritionists is that taking glutamine after your workout is the best time, since your stores of it are presumed to be at their lowest level. Also, taking it in a powder from is much more convenient to use than pills, as well as cheaper. Pills are pretty large and slightly more expensive, whereas powder has no taste and is quickly dissolved in water or any other liquid. The general recommendation would be to dissolve 3 to 6 grams into water along with a quality whey protein powder and then consume this combination within an hour after training, otherwise known as the “post-workout nutrition window”, in which nutrients are believed to be used optimally by the body.

Adding BCAAs is also proven to lower the soreness you may experience in your muscles afterwards, also known as DOMS (Delayed-onset Muscle Soreness). There have been no reports of any heavy side effects, although some say going past 20 grams per day may cause diarrhea. Mixing with hot liquids is not recommended since the heat destroys the glutamine molecule. People who have liver or kidney illness or are undergoing cancer therapy shouldn’t be allowed to take it. The relative lack of documented side effects and how it may interact with other medications, is a reason why you should always consult with your doctor before starting glutamine supplementation.

Here’s a list of foods abundant in glutamine:  steak, chicken breast, ground beef, ham, flounder fillet, skim milk, mozzarella cheese, cheddar cheese, dry roasted peanuts, lentils, soy milk, black beans, boiled eggs etc.

Brief introduction to amino acids

Amino acids are the components that make up proteins, and as any interested in fitness knows, the building blocks of muscle. They are classified into two groups: essential, which means you must get them through diet and non-essential, which means your body can make them in its own. Here’s a short list of both groups:


  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine


  • Alanine
  • Arginine
  • Asparagine
  • Aspartic acid
  • Cysteine
  • Glutamic acid
  • Glutamine
  • Glycine
  • Histidine
  • Proline
  • Serine
  • Tyrosine

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