By Les Willis with James Collier BSc (Hons)
As a supplement, glutamine has been very much maligned and misunderstood; it is time to have a look at this supplement and present a clearer picture. But first a little background reading on the role of supplements in a bodybuilding diet in our article – Do you really need supplements?
What is glutamine?
Glutamine is an amino acid. Protein is made up of amino acids joined together. There are 22 standard1 amino acids, eight of which are essential. The word ‘essential’ is nutritional short-hand for ‘the human body cannot make’.
Supply the body with the eight essential amino acids and it can make the other 14 itself. You will find a lot of sources list glutamine as an amino acid in with the 14, which is not strictly the case. Glutamine is actually a conditionally essential amino acid, which means that under certain conditions your body cannot make enough of it.
A short history of glutamine
It was this ‘conditionally essential’ quality of glutamine that led to it eventually becoming a sports supplement. Unlike many supplements, glutamine was first used clinically with intensive care patients. It was found that people with very severe trauma or burns recovered better when given extra glutamine.
The theory is that, if the body was put under enough stress, it would need glutamine. The studies showed that extra glutamine was required, and that the body did use the metabolic pathways unique to glutamine to aid recovery. As a result, glutamine is routinely added to specialist tube feeds for critical care patients.
Of course, there are a lot of differences between critical care patients who are tube fed and athletes; but the theory remained: if demand was high enough then glutamine would be needed and the supplement L-glutamine was born.
The ‘L’ refers to the chemical structure; more of this later on. Glutamine promised to be a big thing for athletes, the problem was that in study after study nothing much happened. It appeared that in athletes glutamine was a waste of money, or more appropriately at the time, a very expensive waste of money. Despite this, glutamine survived and is still around today.
Why is glutamine still around then?
The problem is that even now studies on glutamine in athletes are not very good. Glutamine is only essential when metabolic stress is exceptionally high; many studies failed to create this situation.
Secondly, glutamine is extremely versatile and can go to a number of places (for example glutamine has a role in the production of antibodies, growth hormone and collagen formation and can be used to make glycogen) – it is like looking for a needle in haystack that may not actually be a needle anymore.
Add to this that sometimes scientists just miss the boat, like a study on the effect of glutamine on the immune system that did not look at whether athletes got more or less sick when using it, and you start to get the picture with the science of glutamine in athletes.
An often overlooked function of glutamine is that it is the nutrient which is the preferred source of energy for intestinal cells; so higher levels mean a stressed digestive system may be able to work more efficiently in helping us absorb more food. This is the key factor and a good argument for glutamine supplementation.
In addition to this, you have advertising copy from the supplement industry and anecdotal evidence that glutamine does work. All of the ‘evidence’ leads to a situation where you can get confused quicker than you can down a protein shake.
Does it work?
That is the million dollar question and the one that scientists failed to answer because it depends on what you mean by ‘work’. Which is not much of an answer at all; so, to summarise the current position: it could. Or, in more detail, it could but we haven’t really found out yet for a number of reasons, and given the poor funding of studies and that glutamine has been all but written off, we are unlikely to find out any time soon either!
Should I use glutamine?
Glutamine has no buzz factor to let you know it is working. In fact, it can be very difficult to know if glutamine has done anything at all; just ask the researchers! If you are someone who needs to feel the supplement working then glutamine is not one for your cupboard.
However, if you are interested in giving glutamine a try then the first thing you need to be doing is taxing your body’s ability to recover. If you don’t do this then you haven’t created the conditions whereby extra glutamine is needed.
So, if you are training hard enough to make Dorian Yates, Ronnie Coleman and Branch Warren call in sick to your training sessions, read on. Secondly, if you are the sort of person who feels they get ill a lot, (i.e. I just got in to a groove and got … scenario that just keeps happening), or if you are pre-contest, then glutamine is certainly worth your attention.
But if you are a bicep boy who does 20 sets of curls then get out the squat rack and save your money for a new sleeveless top instead!
I am hardcore; tell me how to use glutamine!
There are of course a few different types of glutamine, and there are theoretical advantages to the types. The absorption of L-glutamine is impaired by the presence of other amino acids – so other forms can have the technical advantage of not having this problem.
The drawbacks are cost; they are more expensive, and we are not certain how much of this technical advantage actually happens in your gut. The solution is also rather simple: you can take L-glutamine on an empty stomach, for example first thing in the morning. Glutamine is best split dosed, so this can be more difficult.
However the smaller dose also reduces the competition for absorption, so the difference in what is available may not actually be all that great in practice.
L-glutamine vs. glutamine peptides
Before discussing this we need to understand a bit about the physiology of protein digestion: A number of digestive enzymes are involved in the breakdown (hydrolysis) of protein to short chain structures of the protein, known as oligopeptides, or to amino acids.
Amino acids are absorbed in their basic monomer form by an active sodium-dependant transport process, where they are pumped across cell membranes and then into the blood. But there is also a second unrelated process where oligopeptides are taken up and then are further broken down to free amino acids when inside the cells of the intestine rather than in the lumen. The process of this is either enzyme-related or dependent on chemicals.
So there are two unrelated systems in operation to absorb protein, and, as these are independent, this allows a greater uptake of protein, with each method being optimised naturally due to digestion processes. Also ‘peptide’ supplement formulas will have an advantage here as some of the peptides will be fully digested to amino acids before absorption and some will remain peptides and absorbed as such.
Whey protein naturally contains shorter chain oligopeptides so will be digested and absorbed very quickly and it is also naturally high in glutamine.
Both L-glutamine and glutamine peptides and are available as powdered or as capsule supplements. Glutamine peptides do tend to be more expensive as there is a longer process involved in the manufacture of the products.
In theory it may seem that glutamine peptides are superior as both absorption mechanisms will be used, whereas with L-glutamine only the active process is involved. However, as people only supplement with a relatively small amount of glutamine each day (in relation to their total protein intake) and that glutamine is naturally high in whey which most bodybuilders use, on the grand scale of things it doesn’t really matter which you choose as digestion of protein will provide both forms anyway. Indeed, a lot of top bodybuilders are content to use L-glutamine.
How much glutamine do I need?
Large doses of glutamine are very effective at producing diarrhoea, so it is really important not to just whack your daily dose down in one on the first day. Instead, the daily dose should be tapered up to and split. There is no scientific study to tell us the optimal amount; however, available reports say that 15-30g a day is the effective range, with little benefit in going over or under.
It is best to take glutamine on an empty stomach, so first thing in the morning is a great time to get the glutamine going. The most common schedule is first thing, after a workout and then just before bed.
Start with day one of 6g split in to 3 doses and work up to your target as your gut tells you is sensible, it can take a couple of weeks if you are going for 30g a day. Glutamine does not need to be cycled to get an effect. If it’s going to work then you stay on it as long as you are meeting the conditions that make it worthwhile.
Is that it?
In a nutshell, yes. The subject of glutamine can be complicated, there could be a lot of argument over whether it is effective or not, and similarly lots of argument over which form is the most effective and how much you need.
However, don’t buy into the complications; the subject of glutamine can be simplified: either you meet the conditions where it is worthwhile or you don’t. If you do then you need be going for a form that is cost effective because you need at least 15g of it.
So who could benefit from glutamine?
- Very intense trainers
- Trainers who get sick easily
- Pre-contest bodybuilders or athletes
And, how much?
15-30g per day in split doses having tapered up to the target dose
Of which form?
L-glutamine – it is the cheapest and it will give the benefits you are looking for. Other forms offer a theoretical advantage but we are not sure how much of that we get in practice; let alone whether that difference makes a difference to the outcome anyway.
1 Standard means normally occurring – there are lots of other more exotic amino acids in existence that don’t appear in your food unless it was made in a laboratory. However, some people educated beyond their intelligence like to be pedantic on such things.