Tuesday, February 16, 2010


   Until a few years ago, most scientists considered glutamine insignificant. This relates to the previous nutritional status of glutamine, which is an amino acid or constituent of protein. Amino acids are classified as either essential or nonessential. The latter term is easily misconstrued, since the amino acids in the nonessential category are there only because they can be synthesized from other nutrients, including the essential amino acids. Glutamine used to be in the nonessential category of amino acids, since it can be synthesized in the body from branched-amino acids and glutamic acid. But based on ongoing research, most scientists now refer to glutamine as “conditionally essential.”

   Just what are the conditions where you need extra glutamine? How about any kind of stress, both physical and psychological. Under high stress conditions, the body upregulates several systems, many of which are dependent on an adequate supply of glutamine. Under such stress conditions, however, the supply and demand of glutamine in the body isn’t proportionate to the various stress situations encountered. The result of this glutamine imbalance ranges from a decreased immune response--and consequent increased susceptibility to illness--to increased muscle tissue breakdown.

   This is true despite the fact that glutamine is the most abundant amino acid found in the body. Over half the content of amino acids found in the blood amino acid pool is glutamine. In muscle, 60% of amino acid content is glutamine. But when you understand the myriad of effects that glutamine exerts in the body, it isn’t hard to see why the supply of this amino acid can be rapidly depleted.

   Among other functions, glutamine acts as the primary nitrogen carrier in the body; is needed to maintain the right level of acid balance in the tissues; and acts as a direct fuel source for various immune cells and chemicals, as well as for the cells lining the gastrointestinal tract. In muscle, glutamine directly influences both muscle protein synthesis (an anabolic effect), as well as blunting muscle protein breakdown or catabolism. Conditions that involve increased stress, including trauma, surgery, burns, infections, fasting, malnutrition, and yes, even the beneficial stress of exercise, all deplete glutamine stores in the body.
Optimal function of both the gastrointestinal system and immune function takes precedence over muscle protein synthesis during high stress conditions. At this time, glutamine exits from muscle to be used as a fuel source for the intestine and immune cells. This exit, however, leaves muscles open to the negative, muscle breakdown effects of cortisol, an adrenal hormone secreted during stress. When this happens, your muscles shrink and you get weaker.

   If you follow extreme diets that limit either the amount of calories consumed or readily available fuel sources, such as carbohydrates, you risk increased muscle protein catabolism. This has to do with the necessity for the body the maintain a narrow range of glucose, the sugar found in the blood. Your central nervous system depends on an adequate daily supply of glucose, particularly your brain, which is a glucose hog. While the brain and other tissues can adapt to using other forms of fuel, such as the ketone bodies that result from the partial breakdown of fat, the effect is similar to running a high performance car with low grade gas. The car may run, but it will also sputter.

   Glutamine has the ability to act as a direct precursor to glucose formation in the body. The liver easily converts glutamine into glucose in a process called gluconeogenesis. In addition, several studies also show that glutamine may increase the synthesis of glycogen, the primary storage form of glucose found in liver and muscles.

   As noted, many published studies show that glutamine levels in the body drop under stressful conditions, including surgery. These studies show that providing glutamine to people who’ve undergone various surgical procedures or are in a high catabolic state where the body is losing protein rapidly--such as burn patients--acts to prevent excess muscle protein breakdown and keeps the recovering patient in a positive nitrogen balance conducive to recovery.

   The same holds true for other diseases characterized by both high stress and catabolic conditions. Examples of such diseases include cancer and AIDS. Recent research shows that rapid body wasting in such diseases is usually a harbinger of impending death, and glutamine may aid in blocking the excessive loss of lean tissue (muscle) that often occurs under such pathological conditions.

   Glutamine exerts much of its anticatabolic effects through opposing the activity of cortisol in promoting muscle tissue breakdown. But exactly how it fosters increased muscle protein synthesis--an anabolic effect--is still unclear. Taking supplemental glutamine may allow the glutamine in muscle to stay put, rather than exiting during stress conditions to be used as a primary fuel source for the intestinal cells and immune system. If the muscles have enough glutamine available, it may counter the catabolic effects of cortisol.

   Another popular theory relates to cellular hydration. Emerging studies show that when cells have a high water content, or are hydrated, anabolic processes in the cell predominate. When the cell gets dried out, catabolism takes over, and the cell may die. Several hormones and nutrients are known to promote cellular hydration; the most potent of these is glutamine. One study showed that glutamine increased the cell hydration of liver cells by 12% in only 2 minutes.

   Still another way glutamine may exert anabolic effects is through promoting the secretion of anabolic hormones in the body. For instance, a 1995 study published in the American Journal of Clinical Nutrition showed that providing as little as 2 grams of oral glutamine led to a significant increase in growth hormone secretion.

   In another study published the same year, this time in the journal Endocrinology, glutamine was shown to increase the secretion of gonadotropin hormone-releasing hormone (GnRH) from the hypothalamus in the brain. This particular hormone initiates a hormonal cascade that results in increased testosterone synthesis in the body. Testosterone is well-known for its anabolic effects (anabolic steroids are synthetic forms of testosterone), and is also the hormone that dictates sexual desire in both men and women. In this respect, glutamine may serve to rev up your sex life.

   People who exercise often slip into an overtrained condition, whereby the body cannot adequately restore its glutamine stores between exercise sessions. When this happens, the immune system becomes depressed, opening the door to various infections and diseases. Anyone who exercises intensely and regularly would do well to ensure an adequate intake of glutamine to counter the effects of exercise on this nutrient.

   One problem with taking supplemental oral glutamine is the proclivity of the intestinal cells to lop up all the glutamine ingested, since these cells use glutamine as a direct fuel source to help rebuild cells that are shed every 3 days. As a result, up to 80% of oral glutamine doesn’t make it into the blood. And if it doesn’t get into the blood, it can’t get to the muscles. While the problem of glutamine absorption appears formidable, there are solutions.

   The optimal dose for promoting a positive nitrogen balance with glutamine is 0.2 grams per kilogram (2.2 pounds) of bodyweight. This approximates the therapeutic levels of glutamine given to hospital patients. But in a 200-pound man, that amounts to 18 grams of glutamine a day. If you took this all at once, most of it would be sucked up by the intestinal cells, and the rest would be degraded in the liver. The answer is to take small doses of glutamine several times a day. A good single dose is about 3-4 grams. Whey protein supplements also provide about 4-6 grams of glutamine per serving.

   With the high stress conditions that characterize modern day life, you just can’t afford to overlook glutamine if you seek optimal health and freedom from stress-related diseases.

©,2013 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited.

Have you been ripped off  by supplement makers whose products don’t work as advertised? Want to know the truth about them? Check out Jerry Brainum's book Natural Anabolics, available at JerryBrainum.com.


The Applied Ergogenics blog is a collection of articles written and published by Jerry Brainum over the past 20 years. These articles have appeared in Muscle and Fitness, Ironman, and other magazines. Many of the posts on the blog are original articles, having appeared here for the first time. For Jerry’s most recent articles, which are far more in depth than anything that appears on this blog site, please subscribe to his Applied Metabolics Newsletter, at www.appliedmetabolics.com. This newsletter, which is more correctly referred to as a monthly e-book, since its average length is 35 to 40 pages, contains the latest findings about nutrition, exercise science, fat-loss, anti-aging, ergogenic aids, food supplements, and other topics. For 33 cents a day you get the benefit of Jerry’s 53 years of writing and intense study of all matters pertaining to fitness,health, bodybuilding, and disease prevention.


See Jerry's book at  http://www.jerrybrainum.com


Want more evidence-based information on exercise science, nutrition and food supplements, ergogenic aids, and anti-aging research? Check out Applied Metabolics Newsletter at www.appliedmetabolics.com