What are L-Glutamine Benefits and Side Effects?

LIMITED TIME OFFER: Join the planet friendly plant based diet!

Start today for only $9.49

L-glutamine is a buzzword in the fitness industry that seems to be highly acclaimed for its ability strip fat and build lean muscle tissue. Bold claims indeed, so let’s dive in and find out more on the truth behind this amino acid.

Let’s take a deeper look into what l-glutamine’s benefits and side effects are, so you can decide for yourself whether this supplement is right for you and your specific needs.

What is L-Glutamine?

This conditionally essential amino acid is needed in the body for the biosynthesis of proteins. It is the most abundant amino acid in our bloodstream and more than 61% of our skeletal muscle is made up of it. Interestingly, 90% of our body’s l-glutamine is synthesised in our skeletal muscle.

On accasion, there can be a problem with glutamine synthesis in certain individuals. This includes those who’re sick, and premature babies. It is much harder for people in those groups to produce their own.

So, in these cases it then becomes an essential amino acid because of the body’s compromised abilities, hence the reason it is ‘conditionally essential’.

But, do I need l-glutamine supplements?

Glutamine is essential for providing fuel to your cells in order to make other amino acids, and also to produce glucose. It is especially needed in times of stress, both physical and mental, and will be burnt up very quickly under these conditions.

This is one of the main reasons why l-glutamine is so popular in the fitness industry. Because physical training puts constant stress on the muscles and immune system, so therefore a constant supply is vital for hard exercisers.

When intensely training, levels of glutamine are vastly depleted. This in turn decreases overall strength, stamina and recovery time.

In fact, after an intense exercise session it can take up to 6 days for levels to return to what they should be.

This is not good if you like to train at least 3 to 4 times a week, and one of the reasons why exercisers like to supplement.

Muscle repair and growth

Studies show that glutamine supplementation can improve the metabolism of protein. This means it can also be used for muscle repair and growth. This is yet another reason why it is so popular with those on an intense training program or lifting heavy weights.

L-Glutamine And Fat Loss

flat stomach muscles

This popular amino acid is definitely up there as a known fat burner, due to the fact it helps counteract the storage of fat to help regulate weight.

L. glutamine also reduces cravings for sugar and alcohol (which are up there with the worst belly fat producing offenders). And, as belly fat specifically is the most dangerous kind to have in regards to health, keeping it to a minimum is a must.

During intense exercise, l-glutamine also helps with the process of outing fat WITHOUT losing vital muscle mass. This is something that can inadvertently be done very easily done when exercising, and can also be a side effect of weight loss.

Using L-Carnitine alongside L-Glutamine

L-carnitine is another amino acid that also has an impressive profile for fat burning during exercise (this among many other benefits).

The reason this is being mentioned is because it’s often used alongside l-glutamine for even more enhanced fat burning and muscle building. Therefore, it may be worth considering this supplement alongside your l-glutamine. 

There are many other ways you can build fat burning muscle, and you should incorporate some of them into your daily regime and not just rely on one thing. You will always get the best fat burning, muscle building results by using a well rounded array of methods that include diet, exercise, and sometimes added supplements.

zestforever fit program

L-Glutamine And Mood

L-Glutamine can help boost mood due to the fact that it can cross the blood-brain barrier and stimulate the neurotransmitter GABA. This neurotransmitter can also lower feelings of anxiety, depression, and can help you sleep more soundly by reducing symptoms of insomnia.

But, if you are using it for these reasons alone, then you will also need to be sure you are eating a healthy diet and exercising regularly. One supplement alone won’t give you the same benefits, especialy if not used alongside an all round healthy lifestyle.

Exercise and the immune system

An intense workout (especially body building) depletes your stores of l-glutamine. And, as it plays such an important role in the immune system can leave you more susceptible to catching bugs and other illnesses.

Who’s ever noticed getting sick after they know they have overdone it in the gym or out running? Pushing your body too hard too soon, can really have a knock on effect on the immune system. Therefore, it’s vital to keep it strong and healthy with a supplement such as (or similar to) l-glutamine.

It’s worth mentioning that all immune boosting supplements are helpful to exercisers, not just this one.

Immune benefits in itself could be a good reason to use this amino acid, especially if you do like to push yourself during training. And, of course, pushing yourself is certainly something that you need to do in order to get stronger, fitter and leaner.

It’s just probably not a good idea to take this too far, too quickly. Not if you want to keep your immune system firing on all cylinders.

L-Glutamine and Leaky Gut Syndrome

woman's stomach

Another very popular use for l-glutamine is for the healing of the cells in the lining of the gut that may have been damaged by LGS (leaky gut syndrome). LGS can often be a side effect of IBS (irritable bowel syndrome).

This review supports the theory of l-glutamine’s role on gut permeability and how it may help in the prevention of toxins entering the bloodstream.

The inflammation that goes with this disorder can damage the intestinal lining. Experts are not sure whether IBS causes LGS, or vice versa. It is a field that still needs much more research as there is no real cure as of yet, not medically at least.

Other issues caused by leaky gut

Having a leaky gut can cause so many issues in the body that it is fast becoming a leading chronic health issue. According to studies, some of the problems that may lead back to leaky gut are auto-immune diseases, skin problems, allergies, asthma, autism, arthritis, SIRS and type 1 diabetes.

Symptoms of leaky gut may include inflammatory diseases, food sensitivities, auto immune diseases. Also malabsorption of key nutrients such as vitamin B12, magnesium and other enzymes, and mood disorders including autism.

The fact is, there is much debate still raging about whether leaky gut syndrome actually exists, so you may wish to do more research yourself if you feel you may be suffering from it. 

Healing a Leaky Gut

While l-glutamine may help to repair a leaky gut, this is only a small part of the healing process. There are other steps that involve the cutting out of certain foods. These include:-

  1. Cutting out foods such as sugar, grains, non organic animal products and alcohol.
  2. You will then need to add in healing foods with live enzymes, and probiotic foods such as sauerkraut and live yogurt cultures.
  3. It is after this that you would begin the repair process. This is where l-glutamine would potentially come into play with its abilities to heal stomach lining.
  4. You would then need to repopulate the gut’s good bacteria with a good quality probiotic. This process is called the 4R System.

Important: The 4R system is a process that needs to be done either under the supervision of a professional, or with proper understanding of it.

L-Glutamine in a Nutshell

  • Helps protein synthesis
  • Helps strip fat and promotes lean muscle growth
  • Is a great immune booster
  • May help combat insomnia
  • May help boost mood
  • Has other medical uses (of which I would suggest you consult your doctor about before use)

Best times to take l-glutamine supplements

As glutamine levels are at their lowest after you have done a workout or exercise session, then this is one of the optimal times.

If you have it in a powder form, then it would be perfect to add to your post workout protein shake. Alternatively, (and depending on your specific needs) you can take it either in the morning or before bed, which may be a good idea if you’re using it to aid sleep.

How Much L-Glutamine Do I Need?

You should always carefully read the guidance on labels before using any supplements. This is because some supplements are higher dose than others, but generally somebody in an intensive training regime will need between 10 and 15g per day (always take 5g of that after a workout and the rest either morning or evening).

Others who are using this product on a gentler exercise regime (or for reasons unrelated to exercise) may need less. In these cases, you should either speak to a professional or use the guidance on the label.

Which kind of l-glutamine do I buy?

Clickable Image

As with all supplements, they are most definitely NOT created equal. Some are filled with preservatives, chemicals, fillers and many more nasties. Just think, if it’s something you need to take long term, then it would be detrimental to keep filling your body with toxins. Many of these will have names that are unrecognisable, so you won’t really actually know what you’re putting in your body. Or the potential side effects of this added junk.

Make sure you source your l-glutamine from a reputable brand in order to be sure you are getting good quality products that are safe to use.

Possible side effects

It’s important to ALWAYS read labels.

Side effects are pretty rare and usually only occur when too much is taken; or at a different dosage than suggested on the labels. This is yet again another reason to buy good quality products, as the makers will know what they’re talking about when it comes to dosage.

Side effects, when they do occur, are generally mild and may include stomach aches and cramps, nausea, vomiting, mild skin rash, dizziness, itching and headache.

If these happen, you should stop taking the supplement immediately and consult with your doctor who may suggest a different dosage, or to stop completely.


Thanks for visiting ZestForever today!

We are happy to assist you further in the comments section if you need more help.

For a structured fitness plan with easy to do exercises for all fitness levels, please check out our 12 WEEK ZESTFOREVR FIT PROGRAM.

This program is designed to take you to higher fitness levels than ever. It offers delicious, high protein plant based recipes, and at home exercises videos designed by our Personal Trainer Natasha.

Share this post with your friends.

Posted in

25 thoughts on “What are L-Glutamine Benefits and Side Effects?”

  1. This sounds like something that I need! Mostly for insomnia. I have been having a hard time sleeping at night due to a prescription that I take, rendering me so tired during the day. I am going to head on over to your link and try this out. Heck the other benefits are not bad either. Boosting my immune system would be great as well.

    1. Hi Matts Mom, thanks for reading and yes I know exactly what it’s like not to sleep as I suffered insomnia for years until I got into health and fitness. Now it has greatly improved thank god. Yes, I recommend you give L- Glutamine a go to see how it works for you. Anything is worth a shot as what works for one may not always work for another as we are all different. Good luck and please do let me know how you get on.

      Another few tip for insomnia that worked for me is never drink caffeine after 3pm (it really does make a difference) and also, you may benefit from some magnesium at night as this helps relax muscles. Just make sure it’s a good brand! Other sleep herbs include Valerian, passionflower, vervain, lemon balm, lemon verbena an chamomile. You can often buy these in tea form or if you want stronger then supplements. Hope this helps and please keep me informed as I would like to know how you are getting on.

  2. As someone who’s trying to shed a few extra pounds and is trying to get more into health and fitness, I found this article very helpful and informative. I’ll definitely be checking out those l-glutamine capsules!

    1. Hi Jose, glad this article was helpful to you and yes you should give them a try if you are in a serious exercise program, I actually would suggest taking the amino acid L- Carnitine with them as I said in the post for maximum benefits. And if you are only going to take one I would actually recommend you take just the l- Carnitine as it will work better to cut fat. Read my post on L-Carnitine here and decide for yourself.

  3. Enjoyed you post! I thought it was very clear–the benefits of L-Glutamine, and when it might be beneficial to supplement with it. I liked that you pointed out where more research was needed to determine the benefits in certain situations.

    1. Hi Keith, thanks for enjoying the article, yes I always like to be thorough in my posts and tell all sides of the story. Too many people are trying to make a quick buck and up selling products by being totally biased. Really annoying, I only want to promote products that I think can genuinely improve peoples lives.

  4. Such a splendid work you have done here. I had no idea L- Glutamine could helps with mental disorders, and your information about building muscle and fat loss because of L – Glutamine was very interesting. I need some L- glutamines to help me lose my belly fat. Thank you for your information.


    1. Hi Jayden, thanks for reading and I glad you found the article informative. Yes L-Glutamine seems to be a great supplement for many things but remember that for est results, as with most things, you should always combine with a good fitness plan/regime and a healthy diet. It is never usually just one thing that will help with chronic issues, rather a culmination of different thing. You have to hit it from all angles so to speak. Good luck.

  5. That is amazing information. I have never heard about L- Glutamine but you have definitely peaked my interest. One reason being I have insomnia which in my case can be dangerous because I can have seizures while I sleep so getting rest is essential. The other reason is I have IBS and I never heard of the leaky gut so that worries me and is something I will discuss with my doctor because I have been having a lot of difficulties lately. Thanks for this article it came at the perfect time.

    1. Hi Melissa, I am glad you found this article interesting and helpful. I know what you mean about IBS as I have suffered from it for a long time. It is such a hard thing to deal with and every body is different. It is one of the main reasons I researched in depth this subject as I wanted to help myself. The problem with this ‘leaky gut syndrome’ is that even though there is lots of information and research about it now coming in from all angles, many doctors don’t know or have official guidelines of how to treat it or even understand it (this is what I am led to believe anyway), so they may not be too helpful to you.

      I have actually found that since going vegan, which I have been for 9 months, it has virtually cleared up my IBS, so in my mind I can only think that eating animal hormones, which would have put my own hormones out of balance may have vastly contributed to it. As for your sleep, you should probably ask your doctor first before taking these supplements, especially if you have epilepsy as there may be contraindications. But if not, then go ahead and try them, they may help you all round with all of your issues. Good luck and I would love to know how you get on.

  6. Is there a difference between taking L-Glutamine in a protein powder supplement to build muscle and taking it in a capsule? I was amazed to see how much work this one amino acid did. I’ve heard of it before but its not often that you get a full picture of all the functions L-Glutamine actually does in the body. Are there foods that you would recommend as well?

    1. Hi there, yes L- Glutamine is a great little amino acid. I am taking it myself in powder from at the moment and it has really made a difference to my IBS. As for which form to take, it it probably depends on really what you prefer, the powder has a taste to it, which isn’t unpleasant but kind of lingers in your mouth. As with everything, always make sure you but from reputable brands, otherwise you may end up with a product full of fillers and preservatives. Yuck!

      There are lots of recommendations for diet, especially if you are eating for a fitness regime or just general healthy eating. My rule of thumb is always eat whole foods i.e. wholegrains, fruits, vegetables, pulses, nuts, seeds, lean meat (if you are not a veggie like me) and try to eat most veggies, fruits, nuts and seeds in as raw a state as possible to be sure you don’t damage all those nutrients and live enzymes. Please check out my plant proteins foods list for more information. Highest Plant Based Protein Foods List

  7. Hi Stephanie,

    So L-Glucomine helps with all things gut? Well, I drink too much tea and sometimes I feel it, its not nice, as it tends to make me feel bloated and get back acid – and of course from foods.

    Not enough veg in my diet for sure. You think this L Glutamine will help? Oh, if I am anything like my parents, I am going to have arthitis for sure.

    I have been looking for some kind of supplement that is not a fad but actually is going to be some good to be going forward.

    Thanks Stephanie, this was helpful.


    1. Hi Philip, I think arthritis is hereditary so you probably should err on the side of caution and take some kind of preventative measures towards it. If nothing else you should eat a highly alkaline diet like explained in the post, and probably would be good for you to also use lots of turmeric. I have both my parents (who are prone to arthritis) on my homemade turmeric paste and so far they feel great. You should get your parents on it too!

  8. Hi Stephanie,
    Thanks for all the information on l-glutamine, I had no idea that it is so beneficial for many health conditions,. I’m a big believer in plant based diets as well as regular exercise.
    Do you think L-glutamine would be helpful for crohn’s disease?

    1. Hi Fintan, now that’s an interesting question about Crohn’s disease and it seems totally feasible that it would, so I did a little more indepth research for you and it seems to be something that could definitely be beneficial. It makes sense really as l-glutamine help maintain the integrity of the intestine lining and also helps to lower inflammation. As these are both problems associated with Crohn’s then it is definitely worth a try – under consultation of your doctor first of course.

  9. Hi Stefanie,

    Excellent article. Although I know that glutamine is important and I have taken it in the past, I have fallen off with taking it over the past few years. After reading this article I definitely want to incorporate it back into my daily supplements. I learned a few things in this article that I actually didn’t know about glutamine before. Thank you!

    1. Hi Dan, yes I’m like that with my supplements; I come and go off and on different things to find what works for me etc. But L-Glutamine is definitely one of those ones that I feel better with when I’m on them. I guess the thing is you can’t take them all as that would be overkill so you need to work out what is working, and what you should and shouldn’t bother taking.

      As I do a lot of gym work and I am vegan I feel better when I supplement with amino acids, and I’m pretty sure my body needs them.

  10. L-Glutamine could be just the thing I’m looking for. I need something to reduce belly fat and give me energy. I just started a plant based diet too. I have type 2 diabetes and wondering if L-Glutamine will help with diabetes too? I’m exercising with the bike and walking to help shed the pounds and reduce the belly fat but also reduce the sugar cravings. Will this help reduce those cravings?

    1. Hi Rob, I’m glad you have started a plant based diet, you may f8nd the rest of my website helpful if you are a beginner as that is who I aim at.
      As for l-glutamine and blood sugar, I guess in theory it could as it helps to heal the gut which will help stop leaky gut syndrome and thus stabilise your blood sugars. So it can only help. Would probably depend if you do have but issues already, which you yourself would know. For instance, if you’re prone to long term IBS rhen this may well have compromised your gut lining.

    2. Hi Rob, I’m sorry to hear you have diabetes but glad you are finding ways to help heal yourself. They say that they type 2 diabetes can be controlled, even healed through diet alone, so the plant based diet is a great place to start with that. You will find lots of information about this kind of diet on my website if ever you get stuck or have any questions.

      I suppose in a round about way L-Glutamine could potentially help with blood sugar due to the fact that it helps to heal a a leaky gut which is often caused by IBS. Therefore, if you have gut problems then this could be throwing your blood sugar out of wack too!

  11. I am one of those unfortunate ones that had been given entirely too many antibiotics over the years for various ailments going on, before I was able to take back control and go the natural route. So thankful I did that.

    L-Glutamine became one of the few supplements, along with bone broth, that really made a big difference. Leaky Gut is real and it affects people more than they realize.

    1. Hi Holly, oh no, yes antibiotics can really mess with your gut flora and gut lining. Personally, I have not had that many antibiotics in my life but I’m pretty I had leaky gut due to the fact that I had really bad IBS before I went plant based, this carried on for many years due to stress and really messed my gut up. Now thankfully, since my change of diet and use of L-Glutamine I am finally healing.

      I,m glad you have healed your own problems and yes, I have read in countless research articles that so many people have undiagnosed leaky gut that is causing all sorts of problems for their heath.The thing is most conventional doctors still don’t recognise it as a real thing. Crazy!

Leave a Comment

LIMITED TIME OFFER: Join the planet friendly plant based diet!

Start today for only $1

Shopping Cart

Go ahead and sign up to our mailing list to get a FREE eBook PLUS our delicious recipes straight to your inbox.
You won't regret it!

Wait! Before You Leave, Grab yourself a FREE Fast & Easy Recipes eBook...

Scroll to Top