Whether you're looking for a good workout supplement or you want a nutrient that supports your immune system, the health of your intestines and more, chances are you've heard of l-glutamine. Indeed, glutamine has made quite a name for itself thanks to the numerous health benefits it offers.
But if you take a peek at the different glutamine supplements that are available, deciding which one is right for you can be overwhelming. There are powders and capsules, glutamine supplements labeled as "post-exercise" formulas and ones that speak about their benefits to intestinal and liver function...and that's not even touching upon why some glutamine supplements are called "l-glutamine" or "d-glutamine."
No worries: we're happy to demystify glutamine supplementation for you! Here's everything you need to know about the benefits of an oral glutamine regimen, plus how you should take it...and what you can expect from regular use.
What is glutamine?
Glutamine is an amino acid, which ultimately forms protein—one of the building blocks of life. Every cell in your body needs protein to function properly, so you could kind of say glutamine is a big deal.
Your body is able to produce glutamine naturally, which means that it’s a non-essential amino acid. In fact, glutamine is the most abundant amino acid in the human body. (Which doesn't mean supplementation isn't important—as we will explain in a bit!)
L-glutamine benefits
L-glutamine (which is often used interchangeably with “glutamine”—more on that in a minute!) is a precursor to glutathione, which is one of the main antioxidants in your body. And antioxidants help to protect your cells and keep you healthy.
L-glutamine benefits might include supporting a healthy inflammatory response and supplying the cells that line your gut with energy, which in turn benefits your intestinal function.
Emerging evidence points to L-glutamine supplementation as beneficial for heart health too, in addition to liver metabolism.
Additionally, studies using both animals and humans have found that supplementing with l-glutamine can fight exercise fatigue, although it wasn’t found to increase physical performance.
What’s the difference between l-glutamine and glutamine?
Technically, there are two forms of glutamine: L-glutamine and D-glutamine. In fact, all amino acids, except glycine, have an L and D form. Generally speaking, the L form is the predominantly occurring one. Unsurprisingly, L-glutamine is more abundant, and the cells and body use it more commonly. When someone says “glutamine,” more often than not, they’re pointing to L-glutamine.
Foods high in glutamine
Any food that's high in protein will be a good source of glutamine. Some popular choices include:
- Meat (including seafood and poultry)
- Eggs
- Cheeses (cottage cheese, ricotta, mozzarella)
- Nuts and nut butters
- Beans, lentils and other legumes
- Seeds such as pumpkin seeds and sunflower seeds
- Whole grain foods including oats and quinoa
Who should supplement with l-glutamine?
Considering the health benefits that it carries, anyone who would like to improve their gut health, heart function, or immune system, or people who are dealing with a lack of energy, might find glutamine supplements helpful. (Taurine is another option to give you an energy boost.) As always, speak with your doctor first. And supplementation should always complement a healthy, well-rounded diet.
Does l-glutamine have side effects?
You can feel comfortable taking l-glutamine, unless your healthcare provider tells you otherwise. Many studies have proven that glutamine is safe to consume in dosages ranging from five to 45 grams. Dosages between 20 and 30 grams have been found to be well tolerated by humans with no side effects.
How much glutamine should I take in a day?
There isn’t currently a general consensus on how much you should take to sustain healthy glutamine levels, since it’s going to vary from individual to individual. It’s typically safe to start with a dosage between 500 and 2,000 mg. However, your best bet is to follow the product label and also talk with your doctor to determine the right amount for you.
There is one accepted guideline: People who are more physically active might benefit from a higher dosage, compared to a less active person who’s taking glutamine for their general health.
One quick note: glutamine sometimes is included as an ingredient in workout formulas, such as protein powder. Case in point: Life Extension's Wellness Code® Whey Protein Isolate contains 3 grams of L-glutamine. So you won't need to add a glutamine supplement to your regimen if you're already taking it as part of your protein supplement.
Best time to take glutamine
Wondering when to take glutamine? This largely comes down to personal preference. Pick a time of day that you can stick to. If you take all of your supplements in the morning, this might make the most sense. Or maybe you take it before bed.
Ideally, though, you take it when you have an empty stomach. Speaking of which…
Should you take l-glutamine with food?
No. Amino acids are best absorbed when you supplement with them on an empty stomach. So, avoid taking it after meals and snacks.
L-glutamine oral supplement vs powder
Once again, this comes down to personal preference. Some people opt for a glutamine powder that they mix into their workout drink—for example, if they’re also consuming protein powder or BCAAs (branched-chain amino acids) as a powder. (BCAAs can help with healthy exercise recovery.) Others prefer capsules or tablets.
There’s one thing to consider: Oral glutamine as a powder (mixed into a liquid) might be absorbed better. Typically, liquids are absorbed faster than solids. A tablet or capsule is going to be digested over a longer period of time.
Glutamine: supplement combos
Considering the purpose of glutamine, people commonly combine it with other supplements in particular.
Can you take l-glutamine and BCAAs together?
Yes, you can—and this might be a smart move especially if you’re an active person. In one preclinical study, supplementing with glutamine and BCAAs helped support exercise recovery more than supplementing with just one of them alone, which is why a lot of people take them pre-workout and post-workout.
However, keep in mind that as you consume more amino acids, it can potentially inhibit the absorption of glutamine.
Can you take glutamine and creatine together?
You sure can. Creatine promotes exercise performance and strength training and can also encourage lean muscle mass and healthy muscle tissue. Combined with glutamine supplementation, it can provide important nutrients to your cells, fight exercise fatigue, and help you maintain muscle mass. This can be an excellent combination for pre-workout supplements, especially if one of your goals is supporting lean muscle mass. Give your at-home workouts a serious kick in the bum.
Can you take glutamine and glutathione together?
Again, yes! Glutamine is already a precursor to the production of glutathione. However, you can still supplement with both since they each offer their own benefits.
Can you take glutamine and collagen together?
You can! In fact, one study found that glutamine supplementation might help to stimulate collagen synthesis. So, healthy glutamine levels can help encourage your body to better utilize your collagen supplement.
Glutamine for the win!
So whether you're an athlete looking for some post-workout support to encourage better muscle mass and faster recovery, an everyday health seeker who wants to support optimal immune function and intestinal health, or have any combination of these goals, you can't go wrong by adding l-glutamine to your supplement routine.
When taken in the appropriate dose—and of course, alongside plenty of physical activity and a healthy diet—glutamine can work wonders for the body.
About the Author: Megan Grant has a degree in communications from University of Michigan. She has been writing professionally for 15 years, with a focus on nutrition, fitness, and general health. A lifelong competitive athlete, she's fascinated by how the human body responds to food and movement.
References
- Ahmadi, Amirhossein Ramezinai et al. “The effect of glutamine supplementation on athletic performance, body composition, and immune function: A systematic review and a meta-analyis of clinical trials.” Clinical Nutrition, June 2019, https://www.sciencedirect.com/science/article/abs/pii/S0261561418301730
- Arribas-López, Elena et al. “The Effect of Amino Acids on Wound Healing: A Systematic Review and Meta-Analysis on Arginine and Glutamine.” Nutrients, August 2021, https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC8399682/
- Boldt, Andrea. “Foods High in Glutamine to Add to Your Diet.” Livestrong, October 2021, https://www.livestrong.com/article/249890-list-of-foods-that-contain-glutamine/
- Coqueiro, Audrey Yule et al. “Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition.” Nutrients, April 2019, https://pubmed.ncbi.nlm.nih.gov/30999561/
- Durante, William. “The Emerging Role of L-Glutamine in Cardiovascular Health and Disease.” Nutrients, September 2019, https://www.mdpi.com/2072-6643/11/9/2092
- Gould, Rebecca L. et al. “Impact of Supplementary Amino Acids, Micronutrients, and Overall Diet on Glutathione Homeostasis.” Nutrients, May 2019, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566166/
- Haba, Yusuke et al. “Effect of Oral Branched-Chain Amino Acids and Glutamine Supplementation on Skeletal Muscle Atrophy After Total Gastrectomy in Rat Model.” J Surg Res., November 2019, https://pubmed.ncbi.nlm.nih.gov/31254901/
- Hamanaka, Robert B. et al. “Glutamine Metabolism Is Required for Collagen Protein Synthesis in Lung Fibroblasts.” Am J Respir Cell Mol Biol., November 2019, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6827066/
- Häussinger, Dieter et al. “Glutamine and Cell Signaling in Liver.” The Journal of Nutrition, September 2011, https://academic.oup.com/jn/article/131/9/2509S/4687553
- Kreider, Richard B. et al. “Creatine in Health and Disease.” Nutrients, January 2021, https://www.mdpi.com/2072-6643/13/2/447/htm
- Perna, Simone et al. “The Role of Glutamine in the Complex Interaction between Gut Microbiota and Health: A Narrative Review.” International Journal of Molecular Sciences, October 2019, https://www.mdpi.com/1422-0067/20/20/5232/htm
