Glutamine, a conditionally non-essential amino acid synthesized by the body from glutamic acid, is considered the most abundant amino acid found in the body and one of the most important for muscle growth. It makes up over 60 percent of skeletal muscle tissue and 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, making 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, such as in times of extreme stress ( read: weight training).
Glutamine plays a vital role in protein metabolism, cell volumizing, increased production and secretion of Human Growth Hormone (HGH) and anti-catabolism (the breakdown of muscle tissue).
Glutamine is also known as a source of fuel for the cells that line the gastrointestinal tract and is the preferred fuel source for cells lining the small intestine, helping to maintain the health and integrity of the GI tract. Glutamine also serves as a source of fuel for muscle and immune cells.
In addition, glutamine plays a role in maintaining the body's proper acid-base balance. Glutamine is 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.
- 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 a 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: anti catabolism and preserving muscle mass are pretty much the same thing and, to my mind, tie into the recovery process. The concept of anti - catabolism first came to light back in the early 90's as part of the Met-Rx advertising campaign with that product being the first to be considered anti-catabolic. Anti-catabolism really means the preservation of existing muscle mass, or the decrease of the breakdown of muscle tissue. If you understand what happens when you train – the fact that 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. However, you will also find it in many products that promote cell expansion or cell volumizing, a topic I cover a lot in these ingredient fact sheets and certainly one of the newest - and most exciting – supplement categories. 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 and has grown ever since with the development and introduction of several new products, such as nitric oxide.
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, Where there was a time you really didn't have much at all in the way of pre, during and post workout products, you now can utilize all three as part of your advanced supplement program, in effect doing away with the fact that training is catabolic and promoting a anti catabolic state. Imagine the recovery benefits if you remain in a relatively anabolic state during your workouts, or at least minimize catabolism – this would greatly speed up recovery and the muscle growth process. In addition, any pre and intra product promotes cell expansion, in effect helping to promote muscle growth. It's reasons like this that supplements are critical, 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 to important, and the effects to specialized, during the workout time frame and whole food simply does not digest fast enough or produce the same effects. Now, don't misunderstand, whole comes first and is the nutritional cornerstone but supplements do have their place as specialized products performing specific needs at specific times.
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 and often you will hear the terms “ negative nitrogen balance' and “positive nitrogen balance”. These terms are important for muscle growth and really mean the current level of protein in the body, positive meaning you have more than maintenance levels which is good for muscle growth and negative meaning you do not have enough – 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.
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.
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
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 and by it's nature requires more in terms of ingredients needed to make the tablet.
As part of formula products, it comes in pre workout, intra workout, post workout formulas, some vitamin packs and is almost always added in extra amounts (along with bcaa's) in protein powder, bars and weight gain powders. In these products you can find capsules, tablets, powders and chewies.
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, so careful label reading is a must. I recommend taking a stand alone product in addition to any formula's you may be using to get the full benefits. As always, buy to your goal and read the complete label before making your purchase.