What is Glutamine?

Glutamine is a conditionally non-essential amino acid synthesized by the body from glutamic acid. It’s considered the most abundant amino acid found in the body. Also, it’s one of the most important for muscle growth. This amino makes up over 60 percent of skeletal muscle tissue. Additionally, it’s a critical fuel for the digestive tract and immune system. As well,19 percent of a glutamine molecule is made up of nitrogen. This makes it the primary transporter of nitrogen to the muscles. It is also found in high concentrations in the brain, muscles, stomach lining, lungs, heart, kidney, and liver. “Conditionally non-essential” means that the body can’t always manufacture it from other amino acids. This is especially true in times of extreme stress ( read: weight training).

What Else Does It Do?

Glutamine plays a vital role in protein metabolism and increasing cell volume. It also increases production of Human Growth Hormone (HGH) and stimulates its secretion, Finally, it plays a major role in anti-catabolism (the breakdown of muscle tissue).

Furthermore, glutamine is known as a source of fuel for the cells that line the gastrointestinal tract. Also, it’s the preferred fuel source for cells lining the small intestine. This helps maintain the health and integrity of the GI tract. In addition, glutamine serves as a source of fuel for muscle and immune cells.

Glutamine plays a role in maintaining the body’s proper acid-base balance. It’s synthesized from glutamate and ammonia. Ammonia is a toxic waste compound with a high pH value, meaning that it is basic (as opposed to acidic). When ammonia levels are elevated, the body clears ammonia from the blood by synthesizing glutamine. If the blood is too acidic (pH too low), the body can break down glutamine into glutamate and ammonia to increase the pH of the blood.

Back to top

Benefits of Glutamine

  • Primary source of energy for the immune system.
  • It’s converted to glutamic acid in the brain and promotes the synthesis of GABA, an important brain neurotransmitter. For this reason, L-Glutamine may enhance mental function.
  • Helps to maintain the structural integrity of the intestinal lining.
  • Plays a major role in synthesizing muscle protein and cell-volumizing or cell expansion.
  • Helps maintain or preserve muscle mass.
  • It’s an anti-catabolic amino acid
  • Aids recovery from exercise
  • May increase growth hormone levels

That’s quite a list of benefits! If you look closely at the list, several of them tie in together. First, anti catabolism and preserving muscle mass are pretty much the same thing. Both of these tie into the recovery process. The concept of anti-catabolism first came to light back in the early ’90s as part of the Met-Rx advertising campaign. In fact, Met-Rx was the product being the first to be considered anti-catabolic. This means the preservation of existing muscle mass or the decrease of the breakdown of muscle tissue. It’s important to understand what happens when you train. In fact, training is a catabolic event. It’s important to replenish what you’ve burned up during exercise as fast as possible. For this reason, glutamine is highly recommended as a recovery supplement.

Cell Volume & Glutamine

You will also find glutamine in many products that promote cell expansion or cell volumizing. To review, this concept is tied into perhaps the newest theory of muscle growth ( there are several) called sarcoplasmic hypertrophy, meaning the fluid that surrounds the muscle tissue swells causing the muscle to increase in size. This idea began with creatine back in 1993. It has grown since then. This is due to the development and introduction of several new products, such as nitric oxide.

Back to top

Glutamine and Intra Workouts

One of the newest categories of supplements is called the intra workout or during the workout drinks. You will find glutamine a part of most of these products. There was a time when you really didn’t have much at all in the way of pre, during and post-workout products. Now can utilize all three as part of your advanced supplement program. This in effect does away with the fact that training is catabolic. Instead, this approach promotes an anti-catabolic state.

Imagine the recovery benefits if you remain in a relatively anabolic state during your workouts. This would greatly speed up recovery and the muscle growth process. In addition, any pre and intra product promotes cell expansion. This helps promote muscle growth. It’s reasons like this that supplements are critical.

However, these are reasons most anti-supplements advocates do not understand. You can’t accomplish this to the same degree or effect with whole food. Timing and digestion speed is too important. The effects you’re looking for are specialized. This means you need them during the workout time frame. Attempting to do this with whole food is awkward at best. You have to eat enough food to generate the effect. You also have to allow enough time for the food to digest. All of this has to happen within your workout timeframe. Now, don’t misunderstand, whole food comes first and is your nutritional cornerstone. However, supplements do have their place as specialized products performing specific needs at specific times.

Glutamine & Nitrogen Balance

Now, there is one other aspect of glutamine I want to mention: it’s tie in with nitrogen. Nitrogen is a major component of protein. You will hear the terms “ negative nitrogen balance’ and “positive nitrogen balance” used quite a bit. These terms are important for muscle growth and really mean the current level of protein in the body. Positive nitrogen balance means you have levels higher than what is needed for maintenance. This is good for muscle growth. A negative nitrogen balance means you do not have enough. This is bad news for your muscles. How many of you remember the old Nitrogen Test Strips marketed by Weider way back when? Not a bad idea really, you always know where you stand in terms of protein needs. It’s too bad the idea never took off.

Back to top


Bowtell JL, Gelly K, Jackman ML, et al., Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise. J Appl Physiol 1999 Jun;86(6):1770-7.

This study looked at the effects of glutamine in promoting whole body carbohydrate storage and muscle glycogen resynthesis during recovery from exhaustive exercise.

In this study, postabsorptive subjects (subjects have no digestion going on in the GI tract so that no nutrients are forthcoming from any food ingested) completed a glycogen-depleting exercise protocol. After their exercise they consumed 330 ml of one of three drinks, 18.5% glucose polymer solution, 8 g glutamine in 330 ml glucose polymer solution, or 8 g glutamine in 330 ml placebo. In addition, they received a primed constant infusion of glucose for 2 hours.


The authors found that Plasma glutamine concentration was increased after consumption of the glutamine drinks and that oral glutamine alone promoted storage of muscle glycogen to an extent similar to oral glucose polymer. Ingestion of glutamine and glucose polymer together promoted the storage of carbohydrate outside of skeletal muscle, the most feasible site being the liver. The bottom line is, supplemental glutamine can have significant effects on many aspects of your training and help you achieve your weight lifting and sports- related goals.

Hammarqvist F, Wernerman J, Ali R, von der DA, Vinnars E. Addition of glutamine to total parenteral nutrition after elective abdominal surgery spares free glutamine in muscle, counteracts the fall in muscle protein synthesis, and improves nitrogen balance. Ann Surg. 1989 Apr;209(4):455-61.

One study found that patients who had major surgery and were given glutamine did not lose muscle mass during the recuperative period, even though they were inactive.7 The researchers concluded that glutamine supplementation counteracts the decline in muscle protein synthesis that occurs after surgery, while improving nitrogen retention. This research may prove especially useful to those on calorie-restricted diets, who often have difficulty maintaining muscle mass.

Arwert LI, Deijen JB, Drent ML. Effects of an oral mixture containing glycine, glutamine and niacin on memory, GH and IGF-I secretion in middle-aged and elderly subjects. Nutr Neurosci. 2003 Oct;6(5):269-75.

More Studies:

Another study adds to the evidence that that glutamine boosts growth hormone levels. In a randomized, double-blind, placebo-controlled trial of 42 healthy middle-aged and elderly adults, the subjects consumed either a placebo or 5 grams of a nutritional supplement composed mainly of glutamine, glycine, and niacin. The supplement was ingested twice daily for three weeks. At baseline and at the study’s end, the investigators analyzed the participants’ blood. Ingesting the supplement led to a 70% increase in serum growth hormone levels compared to placebo, leading the researchers to conclude that an oral mixture of glutamine, glycine, and niacin can enhance growth hormone secretion in healthy adults.8

Back to top

Glutamine Supplements, Timing and Dosage

As mentioned above, glutamine is a part of many different product types. As a stand alone product, it comes in powder, capsules, and softgels. I haven’t seen it available as a tablet. This is better because a tablet takes longer to digest. Also they require more ingredients to make the tablet.

As part of formula products, it comes in pre workout, intra workout, and post workout formulas. It’s also in some vitamin packs. Of course, you will find it in protein powder, bars and weight gain powders. Often, it will be in extra amounts.

As such, the timing and dosage of the formula products will be product dependent. Many of these are used only once and primarily on workout days.

With stand alone products, timing and dosage can vary greatly from product to product. Therefore, careful label reading is a must. I recommend taking a stand alone product in addition to any formula’s you may be using. This way, you can get the full benefits. As always, buy to your goal and read the complete label before making your purchase.

Back to top

Leave a Reply

Your email address will not be published. Required fields are marked *