Is glutamine the missing link in your gut health?

Glutamine is the most abundant amino acid in our body, and your gut cell’s favourite source of energy.  

But does that mean you need to supplement it to optimise your gut health?

And what about body composition? And endurance training? And getting stabbed?

This episode will answer all of these questions, so you can decide where your hard earned cash should go. 


Today I'm going to be talking about something called glutamine. It's become a bit of a popular supplement, particularly in the gut health space, but it's also got a few other areas where it pops up quite a lot.

Areas like muscle building, its impact on some endurance training things, as well as its use in kind of critical care, emergency department, those sorts of things.And then, of course, inflammatory bowel disease and irritable bowel syndrome and just gut health in general.

So I'm going to go through each of those topics today, give you a bit of an insight on what it is, what it does, how it applies to those topics, just as a bit of background. Pardon me.

Glutamine is an amino acid. It's actually the most abundant amino acid in the body, which is something you probably hear people talk about a lot because I think it makes the idea of promoting supplementing with it a bit more easy to swallow, no pun intended. Because if it's the most abundant amino acid in the body, clearly supplementing will help me get enough of this amino acid for reference. 

Again, amino acids are essentially the building blocks of protein. So proteins are a whole string of amino acids built together to form chains, and different proteins have a different combination of amino acids. Glutamine is what's known as conditionally essential. What that means is, in certain conditions, our body's requirements to increase beyond what we're able to consume from the diet and or create ourself. So essential amino acids are amino acids that we cannot make enough of ourselves or we cannot make it all, and so we have to get them from the diet. And so glutamine kind of is in the middle. It's conditionally essential outside of certain conditions. We don't need to it isn't what we classify as essential because we get plenty from our diet and or we can create some of it ourselves. It fulfills lots of different roles in the body.

One of the main reasons it comes up in the gut health conversation is glutamine is one of the primary or preferred sources of fuel by cells in the gut. And so, again, it makes sense, right? If we want to be supporting our gut cells, we want to be giving them their favourite fuel. But I'm going to park the gut health discussion for a little bit because that's probably the most complex area. And I'm going to go through a few of these other topics a little bit quicker.

The first is muscle building. Put simply, glutamine has no impact on your ability to grow muscle.If you're eating a diet high in protein or with adequate protein and you're following a resistance training program, you're doing everything right. I probably should do a whole podcast on muscle building, actually. But from a glutamine supplement perspective, adding a glutamine supplement to that scenario isn't going to improve your muscle building fat loss, body composition, any of those sorts of things.So if you're supplementing with Glutamine to improve your body composition, you can stop.

The next area of research which is pretty interesting is its impact on endurance training. Now it's not really there about improving your performance or I guess your time or your output, but in endurance training one thing that's really common is some gut upset, some gut distress. And so we're always looking for ways to try and negate that or lessen that. And that's because during times of long endurance training and stress your body does, your gut rather careful now, can become leaky. I won't dive too much into leaky gut and what I will actually call it is intestinal permeability because that's what it actually is. Intestinal permeability is transient. That means it changes, it becomes more permeable and less permeable based on lots of different things. And that's okay, sometimes it can be a problem, but it is also natural for it to shift over time.

In endurance training, unfortunately, endurance intestinal permeability can increase and that can be one of the reasons why we find that gut upset during those training sessions. And so studies have been done to see if Glutamine supplementation can reduce intestinal permeability by measuring a few different markers of intestinal permeability. Seems to be a bit mixed. The best evidence I could find was in a study that assessed it in heat because heat plus endurance training makes things even worse. It was a bit interesting because they did find that supplementing with Glutamine reduced those markers of intestinal permeability but it didn't decrease the gut upset. And so I guess my thoughts are ultimately what we care about the most is the outcome, right? Like if it's reduced a few markers in your blood or your breath, that's good. But if that doesn't result in the actual outcome I'm trying to achieve, then that's not very, very helpful. That's kind of how I interpret that study. Yes, it did reduce those markers of intestinal permeability, which is interesting.But the fact that that didn't translate to a reduction in gut symptoms means that it's not something that I would go and recommend to any ofmy endurance training clients or just anyone who's taking, who's crazy enough to run marathons in the heat. I mean crazy with absolute love, by the way. I'm so impressed but I'd rather die.

So moving right along, the main other area where we're going to be talking about Glutamine is in sick populations and critically sick, acutely sick. Basically things like infection, trauma, cachexia, which is kind of combination of weight and muscle loss often found in cancer but with lots of other conditions as well. In those scenarios, the cachexia, infection and trauma, this causes that increased demand for Glutamine that I discussed earlier. And that's when Glutamine would become what we call essential, where we need to either significantly increase our food intake of it or probably more importantly, we would need to supplement with it. Because what can happen in that scenario is because our needs for Glutamine increase in certain areas of our body. Our body breaks down muscle to cover that gap. Muscle contains a lot of Glutamine. And so if other areas of your body need that Glutamine, they get prioritised scalita muscle. Even though we really like it, overall our body has bigger fish to fry. And so if your gut cells need Glutamine and they don't have enough, your body will break down scalyto muscle to cover that gap. That's not great. So we want to try and stop that as best we can. And there's a bunch of good research showing that Glutamine supplementation in this scenario can be really helpful to retain skeletal muscle and get better outcomes for those patients.

So if you've been burned or stabbed or have a wound that is septic, glutamine supplementation is a great idea. I would hope that in that scenario, I would suggest it's probably a good idea that you let the emergency department doctor, who you're probably dealing with, let them make that call. So again, it's not necessarily a general population recommendation to supplement with Glutamine, again, unless you've been stabbed. But I would probably go to the hospital before supplementing with Glutamine.

Now we come to the meat, the crux of the matter, gut health. And I'm going to sort of discuss gut health a little bit more in the realm of inflammatory bowel diseases, which are things like Crohn's, ulcerative colitis, and they are not to be confused with IBS, which is irritable bowel syndrome, which is a different scenario. So I'm going to talk through inflammatory bowel disease, IBD first. There's a bit of sort of mixed evidence here and I feel like the main reason the evidence is mixed, as we do see some benefit with Glutamine supplementation in some scenarios but not in others. The scenarios where we do see a benefit are quite specific and so I can see a benefit if that specific scenario is yours.

Basically the two factors I would look at is it seems like all of the studies that show a benefit of Glutamine supplementation is for enteral feeding, not oral supplementation. And so enterall just means not oral generally either. If it's enteral, it could be directly into the gut itself via kind of like a line or parental. I actually don't know if they parentally supplement

with Glutamine, but anyway, that is kind of intravenous and so that either way. Again, oral supplementation with Glutamine, which is generally what's pushed and promoted, doesn't appear to have that impact. It's more of a clinical supplementation. The other thing that seems to be really important, particularly in a scenario like Crohn's, is the area in which the Crohn's disease has affected the gut is really important. It looks like Glutamine supplementation when Crohn's is kind of situated more in the small intestine, can be quite helpful. But it does look like if the Crohn's disease is kind of situated more in the large intestine, then the glutamine supplementation doesn't really help with that. And from what I read and from what I understand, I guess the hypothesis there is because there's differences in glutamine metabolism in the cells in your gut. 

So small intestine cells use a ton of glutamine. Large intestine cells, not so much. Which is why I think if the cells in the small intestine are the ones that are kind of being damaged by the Crohn's disease, I can totally understand why giving them more glutamine through again, not oral, but through enteral feedings and supplementation, I can see how that would help. Again, this is not going to apply to too many people who aren't working with who aren't working with the medical team. If you are in that situation, if you're struggling with inflammatory bowel diseases, chances are you have a medical team and they will be able to help you with this. I also wouldn't suggest just blindly enter all feeding or supplementing yourself with anything. IBS is the other area where glutamine comes up a lot, and it's probably the most relevant to the general population because IBS is quite prevalent.

There's also lots of times where just poor gut health, quote on quote things like bloating constipation, diarrhea pain, can get branded as IBS. And then the next step as well, take some glutamine to help improve your gut health. There's a couple of studies here, the two main ones which showed a benefit were very positive. And in science, we're always taught to be a skeptic, and I'm definitely a bit of a skeptic, but if I see a study that is, like, very positive, I don't actually get excited, I get wary. And I would suggest the links are in the show notes for the studies.

But one of the first studies did show a big increase, or rather, sorry, improvement in IBS symptoms. So not an increase or decrease. This was specifically in IBSD, which is IBS with diarrhea symptoms, not IBSC, which is IBS constipation or IBS mixed, which is as. It sounds like a combination of both. So in this study, they gave people suffering with IBSD 15 grams of glutamine a day to see if it improved their intestinal permeability. And it did. I don't know. There's a few parts of it that make me hesitant to jump right into those results. One of the big things is they used the placebo. So basically they split the groups up. It was a randomly controlled, double blind trial, which is great.

What that means is the people in the experimental groups didn't know what they were taking, and the people giving the supplement didn't know what they were giving. But the placebo was Whey protein, which can trigger or exacerbate IBS symptoms. And so I don't like the idea of a placebo potentially making things worse, because that's going to make the supplemental group look even better because they don't have that extra trigger. So that's a big one. 

The other thing was, it was just a small study.That means that statistically, it's what's called underpowered, which means that we need to be very careful about getting excited about those results because there is an increased chance that they did just happen due to chance because of the smaller group. So that's another really important thing to consider.

The other study is where they combined a low FODMAP diet with sorry, they compared a low FODMAP diet, which is the gold standard intervention for IBS, with a low FODMAP diet plus 15 grams of glutamine per day. Again, both groups saw a big reduction in symptoms, which is what we expect thanks to the low FODMAP diet. It did look like the addition of 15 grams of glutamine improved symptoms further. And that's because the low FODMAP diet primarily reduces symptoms by reducing your amounts of fermentable carbohydrates. We can go into that at another time. And so the hypothesis is that glutamine helped reduce the intestinal permeability,which may also have an impact. So the thing, again, there is it was a very small study.

The results were improved from low FODMAP versus low FODMAP plus glutamine, but they weren't significantly better. So, again, it's interesting, but I don't feel like there's enough evidence there to support that. It's also really important to note that both of these studies were in patients with diagnosed IBSD. This is not in healthy populations or people with just a bit of a funny tummy. And I don't want to try and downplay your symptoms or your gut health. You know, if you're struggling with those things, reach out to a good practitioner. But just blindly taking Glutamine for your gut health because it's helpful in certain gut health situations is not a good idea, in my opinion.

In my interpretation of the research, to me,it's kind of like saying, hey, painkillers can help headaches, so we should take painkillers all the time to help my head. Just because they're helpful in that specific scenario doesn't mean they should be taken all the time. It means they should be taken in that specific scenario. So I feel at the moment glutamine supplementation is not something that I would be recommending. There's some mechanistic data. People love getting excited over gut cells in petri dishes, but in actual humans, it doesn't seem to be helpful. So do what you will with that information.

Check out the study links if you want to get a bit more into the weeds.Thanks so much for listening.If you found this interesting, I'd be blown away. If you could share Instagram story, tag me or shoot it to a friend who you think would find it really beneficial.Otherwise, I'll catch you next time.