Skip to main content

When Is The Best Time to Take Glutamine?

When Is The Best Time to Take Glutamine?
Claire Muszalski
Registered Dietitian1 month ago
View Claire Muszalski's profile

L-Glutamine is produced by the body and available in everyday foods, but is also a popular supplement due to its potential health and performance benefits. Glutamine exists in two different forms, L-glutamine and D-glutamine, which only vary in molecular structure. In this article we’ll be focusing on the specific health benefits and side effects of glutamine.

Jump to:

What is L-glutamine/glutamine?

Glutamine, specifically L-Glutamine, is an amino acid (a building block of protein). Amino acids and proteins play many vital roles in our body. Specifically, glutamine helps with the transport of carbon and nitrogen (used for cell division and growth) in our bodies and plays roles in neural function, intestinal function, and boosting our immune system.2 It's made by the body in our muscle tissue and is therefore considered “non-essential”. This means that we don’t have to strictly consume it from our diet.1 However, when our body is under physical (metabolic) stress, it may require more glutamine than it makes on its own.2

This need for additional glutamine, when our body is using it in higher amounts, supports the argument that glutamine is actually “conditionally essential” – meaning there are times when it’s necessary to consume more than what our body produces.3

It makes sense that making our muscles work hard would demand more glutamine – since they’re responsible for creating it in the body. Instances during which our body comes under stress, makes it require additional glutamine.

For more on essential amino acids, check out this article:

Essential Amino Acids | Everything You Need To Know

Find out more about this “essential” ingredient that makes protein so powerful.

2 months agoBy Myprotein

What does glutamine do?

Glutamine is an amino acid, and it’s one of the 20 found in the human body. It’s produced by the body and is also found in food and supplements. As an amino acid, glutamine is used to make proteins alongside other functions.

One of the most important functions of glutamine is its role in supporting your immune system. Glutamine fuels your white blood cells, the blood cells that work to keep your healthy.13

Find 7 other ways to supercharge your immune system here:

7 Easy Ways To Supercharge Your Immune System

Stay feeling your best with nutritionist-approved advice.

5 months agoBy Elle Kelly

Why do you need glutamine?

When we exercise, our body requires energy to be used and expended in order to keep on exercising at the intensity we are performing at. When we expend energy into our workout, we also end up using glutamine within our body simply to help with muscle building and recovery during the aftermath of a workout. However, since most people only obtain glutamine through one’s diet, it is common that many weightlifters do not consume an adequate amount of glutamine that their body requires to maximise performance.

More supps for muscle building:

The 8 Best Supplements For Muscle Gain

Is growing muscle on your agenda? Then you've probably considered supplements – read this first.

Many studies have shown that by taking glutamine post-workout with either your post-workout protein shake or simply by itself, helps prevent the body from using muscle as energy and continues to use carbohydrates, even when you are in a low carbohydrate-depleted state. By taking glutamine intra or post-workout, you will prevent the body from breaking down muscle tissue to be used as energy and will allow you to maintain more lean muscle mass.

Recipes for building muscle:

47 Meal Prep Recipes For Muscle Building & Fat Loss

Your next favourite prep is in here...

9 months agoBy Monica Green

Glutamine food sources

Dietary sources of glutamine include a variety of foods, from animal foods like eggs and beef to vegetable sources like rice or corn.4 Due to this wide availability in food, following a healthy diet can provide adequate glutamine for most people. However, during exercise, glutamine production changes based on the type and intensity of activity.5

Because glutamine is crucial for muscle building, increasing our levels via supplementation after exercise can be beneficial.5 Glutamine supplementation may have a greater benefit on those who have less protein in their diets, like vegans or vegetarians. This is because they may naturally have less of this amino acid.

Many sports supplements are targeted towards strength training, but glutamine has potential benefits for both power exercise and endurance exercise.5

For a meal high in glutamine:

Sticky Sesame Chicken

Now this is how you do chicken and rice.

10 months agoBy Lauren Dawes

Benefits of glutamine

Quick recovery

Research has shown that athletes can benefit from glutamine supplementation to decrease muscle soreness and faster recovery time.5

This amino acid plays a crucial role in controlling glucose (energy) uptake by the muscles after exercise, which can help restore their energy stores for your next workout.6 When your muscles have optimal glucose stores, you can perform better and take longer to fatigue.

Long periods of strenuous training have been shown to decrease blood glutamine levels, making it a potentially useful supplement for your post-workout nutrition plan.1

Increased lean body mass and power

When combined with creatine, glutamine supplementation has been shown to increase lean body mass and power with endurance exercise.7

Studies have shown additional potential benefits, such as:

  • Limited strength loss and reduced muscle soreness8
  • Feeling less fatigued9
  • Longer time until exhaustion in endurance exercise8

Boost in immunity

Additionally, athletes who follow intense training schedules tend to have weakened immune systems due to the constant physical stress of high-intensity exercise.

Research shows that glutamine plays a role in both immune cell production (having enough to fight off germs) and the gut’s function as a physical barrier to infection.3 For these reasons, there may be a potential benefit to your immune system from a glutamine supplement as well.2

When should you take glutamine?

Because glutamine has shown to be in lower concentrations after intense training sessions, it’s popular to take it after a workout to help your muscles to rebuild and grow1 - but it’s not the only time of day to use it.

It can be taken on its own or as part of your post-workout protein shake since protein is another key for muscle recovery and building.1 Glutamine’s role in controlling glucose (energy) usage during workouts means it can also be useful to take it before a workout.6

For these reasons, the timing is primarily based on your goals - if you struggle with energy and pushing through to finish your workout, add it to your pre-workout shake or meal.

If your goal is simply to boost your recovery and muscle turnover, take it with your post workout shake. If you’re training for long periods of time, you can even add it to water that you sip throughout the workout.

Or add it to any of these shakes:

17 High Protein Shakes To Boost Your Daily Intake & How To Make Them

Your daily protein shake will never be boring again.

4 months agoBy Liam Agnew

How much glutamine should I take?

Intakes of 20-30g of glutamine or 0.65g/kg of body mass have been used in research studies and not shown any ill effects in short term use.1 However, you likely only need 3-5g daily to meet your body’s needs.

So, post-workout you should be looking to consume 2-6 g within 20 minutes. If you buy glutamine in powder form then it is very easy to mix with your post-workout whey protein shake.

We offer several glutamine options — follow the packaging dosage to use 1-2 scoops per day.

Potential side effects of glutamine

Glutamine is partially metabolised to ammonia, which can increase blood ammonia and blood glutamate levels in high doses.

Studied doses of glutamine ranged from 5-28 grams per day, with a published observed safe level of a maximum of 14 grams per day, and no increase in plasma ammonia levels.1,2

There are limited potential sides effects of taking glutamine every day, as it’s both made by the body and present in many foods.1,2

Always consult your doctor before taking glutamine or other supplements if you have any concerns.


What are the benefits of L-glutamine?

The benefits of L-Glutamine include faster recovery and between workouts, increased lean body mass and power, and a boost to your immune system.

What is L-glutamine?

L-Glutamine is a non-essential amino acid, meaning your body produces it naturally. However, when your body is under metabolic stress, supplementing it may be beneficial.

When should I take L-glutamine?

The best time to take L-Glutamine is pre- and post-workout, in order to replenish stores which are depleted as you train.

Take home message

Glutamine is an important amino acid that plays many roles in our bodies regardless of our level of exercise. However, the stress that exercise puts on our body can deplete our glutamine levels, making it a useful supplement for athletes.

It shows many potential benefits to performance, recovery, and body mass, with limited side effects. It can also be useful to boost our immune system and help sustain adequate levels in those who follow low-protein diets.



Enjoy this article?



How To Build Muscle | 9 Top Supplements For Bulking

Need a helping hand to make those extra gains?


What Are BCAAs & Their Benefits?

How could BCAAs help you reach your goals?

2 months agoBy Liam Agnew

Do Multivitamins Actually Work?

How effective is this vitamin all-rounder?

2 months agoBy Myprotein

Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you're concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

  1. Gleeson, M. (2008). Dosing and efficacy of glutamine supplementation in human exercise and sport training. The Journal of nutrition, 138(10), 2045S-2049S.
  2. Operation Supplement Safety. (2019). Uniformed Sciences University Consortium for Health and Military Performance. Glutamine. Retrieved from
  3. Hall, J. C., Heel, K., & McCauley, R. (1996). Glutamine. British Journal of Surgery, 83(3), 305-312.
  4. United States Department of Agriculture Agricultural Research Service. (2019, January 29). USDA Food Composition Databases Nutrient List. Retrieved from
  5. ndb/nutrients/index
  6. Legault, Z., Bagnall, N., & Kimmerly, D. S. (2015). 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, 25(5), 417-426.
  7. Iwashita, S., Williams, P., Jabbour, K., Ueda, T., Kobayashi, H., Baier, S., & Flakoll, P. J. (2005). The impact of glutamine supplementation on glucose homeostasis during and after exercise. Journal of applied physiology.
  8. Lehmkuhl, M., Malone, M., Justice, B., Trone, G., Pistilli, E. D., Vinci, D., … & Haff, G. G. (2003). The effects of 8 weeks of creatine monohydrate and glutamine supplementation on body composition and performance measures. The Journal of Strength & Conditioning Research, 17(3), 425-438.
  9. Street, B., Byrne, C., & Eston, R. (2011). Glutamine supplementation in recovery from eccentric exercise attenuates strength loss and muscle soreness. Journal of Exercise Science & Fitness, 9(2), 116-122.
  10. McCormack, W. P., Hoffman, J. R., Pruna, G. J., Jajtner, A. R., Townsend, J. R., Stout, J. R., … & Fukuda, D. H. (2015). Effects of L-alanyl-L-glutamine ingestion on one-hour run performance. Journal of the American College of Nutrition, 34(6), 488-496.
  11. Melis, G. C., ter Wengel, N., Boelens, P. G., & van Leeuwen, P. A. (2004). Glutamine: recent developments in research on the clinical significance of glutamine. Current Opinion in Clinical Nutrition & Metabolic Care, 7(1), 59-70.
  12. Shao, A., & Hathcock, J. N. (2008). Risk assessment for the amino acids taurine, L-glutamine and L-arginine. Regulatory toxicology and pharmacology, 50(3), 376-399.
Claire Muszalski
Registered Dietitian
View Claire Muszalski's profile

Claire is a Registered Dietitian through the Academy of Nutrition and Dietetics and a board-certified Health and Wellness Coach through the International Consortium for Health and Wellness Coaching. She has a Bachelor of Science in Biology and a Master’s degree in Clinical Dietetics and Nutrition from the University of Pittsburgh.

Talking and writing about food and fitness is at the heart of Claire’s ethos as she loves to use her experience to help others meet their health and wellness goals.

Claire is also a certified indoor cycling instructor and loves the mental and physical boost she gets from regular runs and yoga classes. When she’s not keeping fit herself, she’s cheering on her hometown’s sports teams in Pittsburgh, or cooking for her family in the kitchen.

Find out more about Claire’s experience here.