Along with creatine and BCAAs, L-glutamine (glutamine) is a supplement that is one of the most popular yet misunderstood in the fitness industry. Based on current research and anecdotal evidence from our own clients, glutamine is a safe and effective supplement for gut health, immune function, recovery for athletes, and curbing sugar cravings.
Should You Supplement with Glutamine?
Written by Calvin Sun
I often get questions from clients and readers about the function of glutamine, the benefits it can provide, and its proper usage. The purpose of today’s article is to answer some of these common questions and provide you with enough information to decide whether or not glutamine should be a part of your supplement regimen.
What Is Glutamine?
Glutamine is one of the naturally occurring amino acids found in dietary protein and is one of six considered to be a conditionally essential amino acid. While these amino acids are typically in adequate supply, they become conditionally essential when stress, illness, trauma, or other conditions create a need that exceeds its current availability.
Research has found that over-trained athletes have depleted levels of glutamine compared to healthy, well-trained athletes [1, 5]. Glutamine supplementation can be useful for a variety of applications.
Why Should I Consider a Glutamine Supplement?
Glutamine has several benefits including improved immune function [1,2], improved glycogen replenishment after intense exercise [3,4], healing of the gut [6,8,9], and it can even help curb cravings for sweets.
Glutamine and Immune Function
Glutamine plays an essential role in the proliferation of lymphocytes, a type of white blood cell that plays an important role in normal immune function . Other research has found that depleted glutamine levels appear to have a correlation with diminished immune function .
If you have ever engaged in an intense, high-volume training cycle and found yourself more susceptible to colds and other illness, it’s possible that depleted glutamine levels may have played a role. Anecdotal evidence from our own pool of athletes suggests that taking glutamine during these training cycles can help improve immune function and reduce the risk of getting sick during competition season.
Glutamine and Gut Repair
Research has found that glutamine can assist in healing and repair of the gut lining. One animal model study compared glutamine, glycine, and untreated control groups of mice that had undergone irradiation of their gastrointestinal tract. Researchers found that while both glycine and glutamine helped with repair, glutamine proved to have superior results with regard to healing and repair of the gut lining .
What is Leaky Gut Syndrome?
Increased intestinal permeability (also referred to as “leaky gut syndrome”) is a problem that can lead to autoimmune disorders such as rheumatoid arthritis, Hashimoto’s thyroiditis, lupus, psoriasis, and celiac disease.
Symptoms of Leaky Gut Syndrome
Depression, anxiety, migraine headaches, muscle pain, and chronic fatigue are all possible indicators that you might have a leaky gut. Glutamine supplementation can help with repair of the gut lining and reduce the permeability of the intestines.
Treatment for Leaky Gut Syndrome
Of course, if you suspect that you might have leaky gut syndrome or might have an autoimmune disorder, it’s best to consult with a medical professional who specializes in treating these types of conditions. You’ll likely need to remove foods from your diet that cause gut irritation, as well as take other supplements, like probiotics, to assist in restoring your gut health.
Recovery For Athletes
Research has found that the intramuscular concentration of glutamine is correlated with the rate of net protein synthesis . There is also research that suggests glutamine can help promote replenishment of glycogen stores after intense exercise.
In one study published in the Journal of Applied Physiology, researchers compared glucose-only, glutamine-only, and glucose combined with glutamine protocols in athletes who had their glycogen stores depleted. Researchers found that glutamine consumption post-workout resulted in a 25% increase in glycogen synthesis rates compared to the glucose-only group .
Reduce Sugar Cravings
If you’re trying to kick your sugar habit, glutamine supplementation might be helpful for dealing with those sweet cravings. Expert coaches, like Charles Poliquin, often recommend 1 to 2 grams of glutamine in water before meals to help reduce carbohydrate intake or 2 to 10 grams to help curb cravings.
In my experience, this method has worked very well for my nutrition coaching clients. While I couldn’t find any peer-reviewed studies that directly studied glutamine and its role in sugar cravings, other research can help provide a scientific basis for why it works.
In the aforementioned study published in the Journal of Applied Physiology, the ability of glutamine to regulate glycogen synthesis and glucose production might explain why oral supplementation can help reduce sugar cravings. If these cravings are the result of low plasma concentrations of glucose, glutamine can serve as precursor to glucose in gluconeogenic pathways  and, in turn, reduce activation of the hypothalamus which results in increased feelings of satiety and fullness .
What is the Recommended Dose of a Glutamine Supplement?
Glutamine Dose for Gut Repair
If you are trying to repair and heal your gut, you can mix 5 grams of glutamine in water and consume on an empty stomach to help facilitate repair of the epithelial lining of the gut. This procedure can be repeated throughout the day between meals as needed.
Glutamine Dose for Athlete Recovery
If you are an athlete looking to improve net protein synthesis, immune function, and glycogen replenishment, the scientific literature has found that 8 to 10 grams of glutamine to be an effective dose. I would suggest adding your glutamine to your post-workout shake for best results.
Glutamine Doose for Fat Loss
If you are focused on fat loss, you can try using 2 to 5 grams of glutamine mixed in water or in capsule form to help curb sweet cravings throughout the day.
Can I Take Too Much Glutamine?
The upper limit for dosage mentioned in most scientific literature is 0.65 grams per kilogram of bodyweight. For a 150 pound person, that’s about 44 grams of glutamine in a day. In the research I cited for this article, human test subjects took up to 30 grams a day with no acute adverse effects.
What Brand of Glutamine is Recommend?
I like Thorne Research L-Glutamine Capsules. I have personally used this brand and recommend it to my clients and athletes.
Still have a question about glutamine or other supplements? Check out our Post-Workout Supplementation e-book!
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