Of the 20 amino acids that the body uses as building blocks for protein, L-Glutamine is one of the most important.
It’s involved in protein synthesis, recovery, and gut health, to name a few benefits. It’s made by the body except in times of illness or stress. In such cases, it must be supplied by the diet or supplements.
Hard training sessions are an intense form of physical stress. That makes l-glutamine one of the most important amino acids used by bodybuilders, athletes, and fitness enthusiasts.
This guide will reveal the best l-glutamine supplements on the market. Ready? Let’s go!
In a Hurry? Here is our top pick:
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Best L-Glutamine Supplements
- NutraBio L-Glutamine Powder – Best Overall
- Kaged Muscle Microencapsulated L-Glutamine Powder – Best Absorbed L-Glutamine
- Nutricost L-Glutamine Powder – Best Flavored L-Glutamine
- NOW Foods L-Glutamine Pure Powder – Best Budget L-Glutamine
- NOW Foods L-Glutamine 120 Veg Capsules – Best L-Glutamine Capsules
- PEScience TruGlutamine – Best L-Glutamine Complex
- MHP Glutamine SR – Best Sustained Release L-Glutamine
- Optimum Nutrition Pro BCAA Powder with Glutamine – Best For Bodybuilders
- Gut Assist Leaky Gut Repair – Best L-Glutamine For Intestinal Health
Reviews – The Best L-Glutamine Supplements
NutraBio L-Glutamine Powder – Best Overall
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NutraBio L-Glutamine Powder contains 5g Kyowa Quality fermented glutamine per serving. This is trademarked vegetable-based glutamine that’s HPLC tested for quality and 99.98% purity.
Besides being vegan-friendly, this product is non-GMO, gluten-free, certified kosher, and hypoallergenic.
Like all NutraBio products, L-Glutamine Powder features full label transparency. It’s unflavored and can be mixed with any beverage or sports powder, such as a pre-workout or recovery drink.
The quality and label transparency make NutraBio the best overall l-glutamine powder.
PROS
- Tested To Be 99.98% Pure
- 5g Vegetable Based Fermented Glutamine Per Serving
- Trademarked Kyowa Quality Glutamine
CONS
- Poor Taste Seems To Run Across Most Brands
Kaged Muscle Microencapsulated L-Glutamine Powder – Best Absorbed L-Glutamine
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Kaged Muscle Microencapsulated L- Glutamine Powder is vegan-sourced and supplies 5g of fermented glutamine per serving. Fermentation can be defined as the chemical breakdown of foods which in turn improves absorption.
This product is not like other l-glutamine supplements thanks to its special microencapsulation technology. This means it is enclosed in a plant-protein complex that acts as a microcapsule.
This is designed to protect the glutamine as it passes through the intestinal system.
Why is this important?
Because often, glutamine is not used for muscle-related benefits. It enters the bloodstream and can end up being used for other functions.
Microencapsulation helps the glutamine do what it is intended for – support muscle growth and recovery, among many other benefits.
Finally, Kaged Muscle L-Glutamine contains no other ingredients and is unflavored.
PROS
- 5g Fermented L-Glutamine Per Serving
- Microencapsulated For Improved Absorption
- No Animal Byproducts Used – Plant Sourced
CONS
- Some Users Feel The Flavor Is Chalky
Nutricost L-Glutamine Powder – Best Flavored L-Glutamine
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Nutricost L-Glutamine Powder supplies 5g of vegan-friendly l-glutamine per serving. There are no other ingredients.
Nutricost L-Glutamine is manufactured in a GMP compliant, FDA registered facility. It’s also a non-GMO product and like all Nutricost products, it’s 3rd party tested for quality, purity, and potency.
This product comes unflavored so it can be mixed with water, juice, or the beverage of your choice. It also comes in blueberry and fruit punch, making this the best-flavored l-glutamine.
PROS
- 5g Glutamine Per Serving
- Vegan-Friendly
- 3rd Party Tested
CONS
- Some Users Do Not Like The Taste
NOW Foods L-Glutamine Pure Powder – Best Budget L-Glutamine
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Like many of the products in this guide, NOW Foods L-Glutamine Pure Powder contains 5g free form l-glutamine per serving.
“Free Form” means that the amino acid is in its purest state and bypasses digestion. Instead, it goes directly into the bloodstream. This is the only ingredient.
NOW L-Glutamine is vegan and is tested for quality and purity. This is an unflavored powder that is suggested to be mixed in juice. It can also be mixed in other beverages but may not mix well in water.
Along with the high quality of this product, NOW Foods L-Glutamine Powder comes in at a reasonable price.
PROS
- 5g Free Form L-Glutamine Per Serving
- Bypasses Digestion & Goes Right Into The Bloodstream
- Unflavored – Mixes With The Beverage Of Your Choice
CONS
- Grainy Texture – May Not Mix Well In All Beverages
NOW Foods L-Glutamine 120 Veg Capsules – Best L-Glutamine Capsules
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Some users prefer a powder because it can be added to protein shakes or pre-workouts. Others prefer a capsule. NOW Foods L-Glutamine capsules are available at 1000mg per serving. The capsules are made of gelatin and are designed to be easy to swallow.
As indicated above, NOW Foods is a premium quality, vegan, non-GMO, GMP quality assured brand. It’s also gluten-free, kosher, dairy-free, egg-free, nut-free, and soy-free.
If there’s a downside, it’s that you may need quite a few capsules per day, based on dosage. Some sources suggest as much as 20g of glutamine per day in divided doses. Even if you take just 5g a day, that’s 5 capsules of the 1000mg version.
PROS
- 1000mg Free Form Glutamine Per 1 Capsule Serving
- Certified For Quality
- Vegan
CONS
- A Capsule-Based Product Requires Quite A Few Doses Per Day
PEScience TruGlutamine – Best L-Glutamine Complex
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PEScience TruGlutamine is the best l-glutamine complex because it contains 10g of patented Sustamine glutamine per serving. Sustamine is a blend of l-glutamine and l-alanine. The advantage of this form of glutamine is superior absorption
The 10g serving is one of the strongest dosages available. Some users may take up to 20g per day of glutamine, this meets that requirement in only two doses. TruGlutamine is flavorless so it can be mixed with any other beverage.
The downside is that this product contains other ingredients including artificial sweeteners. This is to offset possible bitterness in the taste. Despite the use of additional ingredients, this product is lab-tested for quality.
PROS
- Features 10g Patented Sustamine Glutamine/Alanine Blend
- Offers Superior Absorption
- Tasteless
CONS
- Contains Artificial Ingredients
MHP Glutamine SR – Best Sustained Release L-Glutamine
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MHP Glutamine SR provides a unique approach to l-glutamine supplementation. There’s 5g per serving, just like most of the products in this guide.
The thing that sets MHP apart is 1g of a patented sustained release complex consisting of soybean oil and soy lecithin. This slows digestion and absorption enough to cover a 12 hour period.
MHP calls this micro-feed technology, and they use it in many of their products. This is an advantage for any users that lead a busy lifestyle, especially bodybuilders and athletes.
MHP Glutamine SR is the best extended-release glutamine available.
Unless you are taking mega-doses, you only need to take this product once a day. It mixes with any beverage and is unflavored, so the taste of your drink will not be affected.
PROS
- 5g Glutamine Per Serving
- Special Micro-Feed Technology Slows Digestion & Absorption
- 167 Servings Per Container
CONS
- Some Users Don’t Like The Taste & Texture
Optimum Nutrition Pro BCAA Powder with Glutamine – Best For Bodybuilders
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Optimum Nutrition Pro BCAA combines 8g BCAAs with 5g glutamine. These 4 amino acids make up almost all the protein found in muscle tissue. The combination supports protein synthesis, recovery and muscle protein breakdown.
These benefits make this product both anabolic and anti-catabolic. All of these features make Pro BCAA with Glutamine the best choice for bodybuilders.
This is a flavored product but has an unflavored option, so it can be mixed with anything. Additionally, there are no artificial ingredients in Pro BCAA.
PROS
- 8g BCAA With 5g Glutamine
- Anabolic/Anti-Catabolic Formula
- There’s 7 Flavors, Including Unflavored
CONS
- May Not Mix Well In All Beverages
Gut Assist Leaky Gut Repair – Best L-Glutamine For Intestinal Health
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Gut Assist Leaky Gut Repair is a glutamine-oriented formula designed to support healing of the protective membranes in the GI tract. A healthy-functioning gut lining promotes the proper delivery of nutrients.
L-Glutamine is the most dominant amino acid in the body. It’s essential to normal gastrointestinal function. Also, glutamine is a nitrogen carrier in the body, which is essential in cellular healing.
One serving contains 3g glutamine, plus arabinogalactan, aloe, and licorice. It’s sugar-free and there’s no other listed ingredients. It’s unflavored and the suggested use is to mix it in water.
The features and benefits of this product make it the best glutamine for intestinal health.
PROS
- Supports Intestinal Health
- 3g L-Glutamine
- Can Be Taken With Digestive Enzymes, Pre And Probiotics
CONS
- Some Users Do Not Like The Taste
Buying Guide – How To Choose The Best L-Glutamine Supplements?
What Is It
L-Glutamine is the most dominant amino acid in the body and makes up 61% of skeletal muscle tissue. Additionally, glutamine consists of 19% nitrogen, which means it’s the main transporter of nitrogen into your muscle cells.
Glutamine is known as conditionally essential. What does that mean? Conditionally essential amino acids are made by the body. However, individuals suffering from illness do make enough on their own.
As we will see below, stress, including physical stress, also increases the body’s demand for glutamine. Therefore, in these cases, individuals need to get glutamine through supplements and diet. (1)
What Does L-Glutamine Do
Supports Muscle Growth
As noted above, the body’s demand for glutamine increases during stress, which includes the physical stress of intense training sessions. It also includes other types of stress, such as injury, illness, and even severe calorie restriction. This means it needs to be replenished. In terms of your workouts, while it may be in your pre-workout, it should be included in your post-workout shake.
Additionally, l-glutamine plays a part in protein synthesis. One way it does this is by supporting BCAA metabolism. BCAAs, especially l-leucine, stimulates protein synthesis. This process is considered a direct trigger of muscle growth. It also acts as an anti-catabolic by preventing muscle protein breakdown. This helps the body stay in an anabolic environment. Finally, glutamine is believed to support recovery. Muscle growth cannot occur if you have not recovered from your workout.
Gut Health
Gut health is an important component of overall health because it helps strengthen the immune system. It also helps the body flush out toxins.
Leaky gut, also known as “leaky gut syndrome”, is a condition of increased intestinal tract lining penetrability.
The intestines and stomach have a layer of mucous that covers the lining of the intestinal tract. This protects the stomach and intestines from stomach acid and microbes. The lining consists of spaces known as tight junctions. After you eat a meal, the tight junctions loosen up to allow optimal absorption of water and nutrients. Additionally, these tight junctions prevent absorption of toxic substances. (2).
In terms of a leaky gut, these tight junctions loosen up and allow toxic substances and bacteria to enter the body. This can cause inflammation in the body, stimulating such symptoms as fatigue, abdominal cramps, and appetite loss.
One of the ways glutamine helps heal the gut is the use of glutamine as energy. Here’s how that works: Glucose is used by the body as the primary source of energy. Sometimes our bodies do not have enough glucose and must look elsewhere to meet energy demands. The intestinal system can help meet this demand by using glutamine as a source of energy by converting it to glucose. Beyond the use of glutamine as an energy source, it also increases mucus production and decreases gut permeability. (3,4)
Immune System Health
L-Glutamine significantly affects the immune system function. The lymphocyte and macrophage cells in the immune system cells rely on glutamine as a primary fuel source. This means that the demand for glutamine increases if the immune system is stressed.
Recovery from Injury and Illness
Levels of the catabolic hormone cortisol increase when our bodies undergo stress, illness, or trauma. This includes the stress of intense workouts. Additionally, in cases like this, glutamine stores can be depleted. This is one reason why we may feel sick when dealing with a high amount of stress. As L-Glutamine levels are restored, it helps relieve these symptoms and enhances recovery.
Also, glutamine can support repair caused by trauma and damaged muscles. This is because the body makes more protein in events like this, and as we have seen above, glutamine is one of the most dominant amino acids in muscle tissue. This means more glutamine will be available for use. (5,6,7,8)
How To Use L-Glutamine
Glutamine is available in powder or capsules as a stand-alone product. It’s also commonly included in many BCAA/EAA formulas, pre-workouts, intra-workouts, and recovery supplements.
To use l-glutamine, consume your glutamine product of choice as directed on the label. If you are using glutamine as a stand-alone product, try adding 1 serving or 5g to the pre-workout of your choice. Add another 5g to your intra-workout drink, and add another 5g to your recovery drink. You can have a final 5g 6-8 hours later to support recovery.
On off-days, add 1-2 servings to your protein shakes. You can take 20g a day safely because Glutamine has a high turnover rate. No negative effects have been reported from the use of high dosages.
Conclusion
L-Glutamine is an important amino acid to add to your supplement arsenal. As we have seen, it’s not just for bodybuilders. The immune and intestinal health benefits may l-glutamine one of the most important amino acids you can take.
The best overall is NutraBio L-Glutamine Powder. NutraBio is among the highest quality supplements on the market. This product contains Kyowa Quality fermented L-Glutamine, a trademarked form of glutamine. It’s also one of the purest forms of glutamine available.
Additionally, NutraBio features extreme label transparency on every product they make.
If budget is your main concern, NOW Foods L-Glutamine Pure Powder is the best choice. NOW is another high-quality brand that always features their quality standards on the label of every product they make. The best thing is, they feature premium quality at an exceptional price point.
If you’re a bodybuilder, athlete, or fitness enthusiast looking for the best choice for muscle growth, Optimum Nutrition Pro BCAA Powder with Glutamine is the one for you. This product features 8g BCAA with 5g glutamine. This is a great combination that supports protein synthesis and recovery.
There’s an L-Glutamine supplement for everybody. Use this guide to find the best option for you!
References:
- Hall, J C et al.; “Glutamine.”; The British journal of surgery vol. 83,3 (1996): 305-12. doi:10.1002/bjs.1800830306; https://pubmed.ncbi.nlm.nih.gov/8665180/
- Leslie M. (2008). Tight junctions loosen up. The Journal of Cell Biology, 181(4), 568. https://doi.org/10.1083/jcb.1814iti3
- Glutamine promotes intestinal SIgA secretion through intestinal microbiota and IL-13. – Abstract – Europe PMC
- Wang, B., Wu, Z., Ji, Y., Sun, K., Dai, Z., & Wu, G. (2016). L-Glutamine Enhances Tight Junction Integrity by Activating CaMK Kinase 2-AMP-Activated Protein Kinase Signaling in Intestinal Porcine Epithelial Cells. The Journal of nutrition, 146(3), 501–508. https://doi.org/10.3945/jn.115.224857
- Candow, D G et al.; “Effect of glutamine supplementation combined with resistance training in young adults.” European journal of applied physiology vol. 86,2 (2001): 142-9. doi:10.1007/s00421-001-0523-y; https://pubmed.ncbi.nlm.nih.gov/11822473/
- Legault, Zachary et al.; “The Influence of Oral L-Glutamine Supplementation on Muscle Strength Recovery and Soreness Following Unilateral Knee Extension Eccentric Exercise.”; International journal of sport nutrition and exercise metabolism vol. 25,5 (2015): 417-26. doi:10.1123/ijsnem.2014-0209; https://pubmed.ncbi.nlm.nih.gov/25811544/
- Street, B. et al.; “Glutamine Supplementation in Recovery From Eccentric Exercise Attenuates Strength Loss and Muscle Soreness”; Journal of Exercise & Fitness; vol. 9,2 (2011): 116-122; https://www.sciencedirect.com/science/article/pii/S1728869X12600070
- Calder, P C, and P Yaqoob.; “Glutamine and the immune system.”; Amino acids vol. 17,3 (1999): 227-41. doi:10.1007/BF01366922; https://pubmed.ncbi.nlm.nih.gov/10582122/
