L-Glutamine Facts - Benefits, Side Effects & Dosage

How about some L-Glutamine facts? Levo-Glutamine (or ‘L-G) is a naturally-occurring amino acid.

Woman describing facts about amino acids, and how they improve bodybuilding and exercise.

Synthetized in our bodies and accounts for over half of our entire amino granary. It is commonly known to be ‘conditionally essential’. In other words, while most of the time we have enough of it to meet the demand of our daily activities, when we’re stressed our supply of L-Glutamine is used up more quickly.

And by stressed we mean either physically (when we exercise) or physiologically (when we are unwell). Hence why L-G is recommended by a plethora of nutritionists.

Under today’s heading though, we want to look at the impact of the amino on athletic performance

What Does Glutamine Do For An Athlete?

Sports specialists believe that having less L-G in your muscles post-workout will hinder the development of muscle and your general rate of recovery. It is for that reason you will notice when browsing sports nutrients many are said to include L-Glutamine.

But wait, there’s more…

L-G is also thought to be responsible for an increase in metabolism which in turn can promote weight loss. So, regardless of your motivation for a visit to the gym, L-G seems likely to aid us all.

We shall look more at how beneficial taking L-Glutamine before or after a workout is in just a moment. But first, let’s take a look at some amino acid basics and what natural sources of L-Glutamine there are…

Where Does L-GLUTAMINE Come From?

Amino acids like L-GLUTAMINE are made in your muscles and from there are carried around the body in the blood. Although the healthy human makes their own L-G there are some sources of the amino acid found in food. You will notice that these foods are the ones high in protein… no coincidence!

  • Beef, chicken, fish,
  • Eggs, milk, cheese
  • Beans, beats, cabbage, spinach
  • Parsley, celery, kale


L-G is denatured by cooking and ambient heat, which means it begins to break apart. When that happens, its natural benefits are less. We’re not suggesting you eat raw meat, but if you are faced with a food stuff that can either be eaten cooked or uncooked it would be better to head for the latter option.

A cheese-product called Quark is an excellent source of natural L-Glutamine, and yoghurt and milk are particularly high in the amino (but contain less than Quark). Yet even these protein-rich food stuffs are delivering, according to scientists, just 4-8% of the L-Grequirement for someone who exercises regularly and vigorously.

When to take l-glutamine

As with any amino acid which is used in the production of muscle fibre the trick is in having your supply greater than your demand. On this basis, some suggest on-boarding an L-GLUTAMINE supplement after your exercise (to the amount of 0.1 kilograms per kilogram of body weight) increases your post-workout levels by 50%. In fact, some nutritionists propose that taking six times as much increases still further your recovery rate after vigorous exercise.

Glutamine before or after workout?

Like any sports supplement, the question for the user is when is best to take it. Generally speaking, sports supplements have been taken post-workout to replenish the body’s reserves.

Which makes sense: after exercising, our muscles are in an anabolic state and are, basically, ‘hungry’ for all the nutrients they can get. However, there is no hard and fast rule for post-workout supplementing and a regular intake of L-G or any other mineral will provide the body all that it needs.

If you calculated an appropriate value to be around 30 grams a day you may want (on training days) to take 10 grams of L-G before, during and after your workout. Or split the dosage still further and take a 5-gram dose at regular intervals throughout the day.

How does it help to keep you healthy?

Scientists have shown that amino acids such as L-G are not just valuable for our muscle development. Amino sugars (which it helps to make) are known to be useful in warding off debilitating skeletal complaints such as osteoarthritis.

A good level of L-Glutamine also affects the creation of growth hormone. For those of you who seek to build muscle, your natural growth hormone spikes muscle development and also increases your energy levels…

‘Human growth hormone can turn back your body’s internal clock, helping you rapidly build muscle, slash fat, and increase libido, all while sending energy levels through the roof.’

(www.muscleandfitness.com, 2018)

L-Glutamine + Training = ?

So, what of L-GLUTAMINE'S impact on athletic ability?

In short, it is one of the major ingredients to thick, lean skeletal muscle. And whether your goal is to be conditioned and injury-resistant or to be the next Arnold Schwarzenegger it’s worth thinking about how valuable such an amino is.

Not only does it supply nitrogen and carbon to your flexing muscles, but so too does it promote cell expansion post-workout. L-GLUTAMINE engineers the ‘pump’ that some of us seek by drawing into the muscle creatine, water and carbs: materials all necessary for cell growth.

It has also been suggested that this amino acid slows down the body’s release of a chemical called Cortisol: a known tissue destroyer. By doing this, your athletic stamina is not only maintained but increased.


By being used in this way your L-G reserves are fast depleted – after vigorous exercise by as much as 30%. Which is why you will feel exhausted more quickly and why making sure you have a sufficient supply is necessary. Without sufficient levels of L-G your muscles will be weaker and less likely to grow.

The effects of L-Glutamine deficiency can be summarised as follows:

  • General weakness
  • Reduced stamina
  • Zero muscular hypertrophy (no muscle build)
  • Low mood


Food rich in protein cannot always replenish our L-G levels, and not all of us can afford the time or expense of shopping for such foods.

SCI-MX has an array of protein matrices containing L-G as either an isolate or bonded with other amino acids. By combining aminos and delivering them with carbs and other nutrients, the body can more easily absorb the L-GLUTAMINE dose into the skeletal muscle rather than it being used by the liver and kidneys.

Our WHEY PLUS HARDCORE for example contains 4.9 grams of free form L-G and 0.9 bonded. One serving should be had 30 minutes before training and another immediately after with a maximum of three servings a day. That alone is the equivalent of around 18 grams of L-G each day.

Sports nutritionists have highlighted the numerous benefits associated with maintaining a healthy (LG) stock. These include:

  • Greater muscle development: L-Glutamine promotes protein synthesis in the muscles.
  • Less muscle atrophy: L-Glutamine inhibits the breakdown of muscle fibres.
  • Better recovery: L-Glutamine inhibits the release of stress hormones and improves recovery.
  • Greater strength: L-Glutamine promotes greater explosive force in large muscle groups.
  • Increased stamina: In line with its capping stress hormones, L-G also drives nitrogen to the muscles.
  • Increased immunity: L-Glutamine is proven to help the body fight infection and illness.
  • Better mental alertness: L-Glutamine aids neurotransmitters and can improve brain function.
  • Better physical conditioning: L-Glutamine is known to positively affect cardiac hormones.

Side Effects

Like any substance taken into the body via food or supplements there is always a danger that what it is joined to will cause side effects. If you are considering taking any supplement you should consult your doctor beforehand.

In comparison with some substances that are not made by the body, L-G as a supplement is a synthetic version of what we already have inside us. Thus, while some users have reported nominal reactions to its ingestion, the biggest issue to watch out for is an L-Glutamine overdose / overload.

‘A recent 13-week toxicity study concluded that the "no-observed adverse effect level" (NOAEL) for L-G occurred at the highest daily dose provided to male and female rats.’

(www.bodybuilding.com, 2018).

It is important to remember that our bodies are very individual machines. As such, some may be more sensitive than others to increased levels of nutrients.

The reported side effects of too much L-Glutamine are:

  • Bloating and constipation
  • Nausea and stomach pain
  • Swelling of the extremities
  • Chest pain
  • Muscle and joint pain
  • Hearing difficulties
  • Illness and infection

It is vital that you call your doctor if you experience any of these signs.

And finally…

In summary, for anyone looking to gain the most from their gym visits, L-G is an essential nutrient.

It bolsters the usual protein supplements by providing valuable support for muscle synthesis and bodily health.

We have learned that L-G is the biggest component of our bodies’ amino acid pool but that it is quickly depleted. We have also learned that its depletion often leads to illness and injury, or at the very least decrease athletic ability and muscular atrophy.

That is why supplementing with a base matrix containing L-G is called for, even if your exercise is moderately vigorous.

Look again at our list of protein supplements containing L-Glutamine and for more advice contact us.

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