l-glutamine for gut barrier function

Does longevity begin and end with gut barrier function?

L-glutamine is the most abundant amino acid in circulation. It is used by the body in many ways — including for optimal immune system function and production of mucus. Glutamine is found in foods high in protein, such as meat, dairy, nuts, and whole grains. The body can also synthesize glutamine under normal conditions.

Longevity benefits:
A higher glutamine intake is associated with a lower risk of all-cause mortality and cardiovascular mortality. [ref] In people with diabetes, the reduction in all-cause mortality is even greater.[ref]

Let’s take a look at why this amino acid is important and when it might be helpful to supplement with it.

When do we need more glutamine?
When the body is under stress - such as after surgery, when training for a marathon, when burned, or with radiation exposure - the need for glutamine increases above what is normally available. Thus, glutamine is used for trauma, significant burns, and for counteracting the effects of radiation therapy in certain types of cancer.

Glutamine is essential in gut barrier health:
The intestinal epithelium utilizes glutamine for part of its energy requirements. Glutamine is also essential in the production of the mucosal barrier that lines the gut and protects it from bacteria and digestive enzymes. In addition, glutamine is a precursor of the synthesis of glutathione, an important antioxidant in the gut and throughout the body.[ref]

What happens without enough glutamine?

Looking at the negative side of the picture can give us a glimpse of the importance of glutamine.

• Genetic reduction of glutamine uptake in the intestines is linked to gut inflammation and inflammatory bowel disease.[ref]

• Glutamine deprivation causes reduced mitochondrial energy and increases beta cell dysfunction in the pancreas in diabetes.[ref]

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Circling back to prior articles: Connecting glutamine, autodigestion, and microplastics

I’ve written previously about why the gut mucosal barrier is integral to health, and why we literally can’t live without it (autodigestion from pancreatic enzymes). I’ve also written on microplastics in food being absorbed into the bloodstream and subsequent negative effects on health span. Microplastics are a dual threat in that they damage the intestinal mucosal barrier, which then increases their absorption.[ref] My takeaway is that the gut mucosal barrier is essential for longevity and healthspan - thus making optimization important, as well as avoiding microplastics.

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Let’s take a look at how and when supplemental glutamine is useful for mucosal barrier function. (Note that I’m cherry-picking here — there are also lots of studies on glutamine for radiation, IBD, sickle cell anemia, sepsis, and more.)

IBS: Irritable Bowel Syndrome

L-glutamine supplementation has some good studies on it for IBS:

• For post-infectious IBS-D, patients with an enteric infection were randomized to get either l-glutamine or placebo for 8 weeks after the infection. The l-glutamine group had a 14-fold decrease in IBS-D compared to placebo. Plus it reduced intestinal permeability.[ref]

• Glutamine (15g/day) plus a low FODMAPs diet was more effective for reducing IBS symptoms compared to FODMAPs alone.

• Animal models of IBS show that glutamine reduces intestinal permeability.[ref]

Respiratory infections:

• Athletes undergoing extensive training have immune suppression and get more respiratory infections. A study on athletes with an intensive training schedule showed that l-glutamine reduced respiratory infections. L-glutamine supplementation for three weeks increased salivary IgA and nitric oxide, and it decreased the number and duration of upper respiratory infections.

Pancreatitis:

• A meta-analysis of studies on glutamine for pancreatitis showed that glutamine supplementation reduced mortality by 70%.[ref]

Gut microbiome:

• A clinical trial showed that 14 days of supplementation with l-glutamine (30g/day) shifted the gut microbiome from one associated with obesity to one that resembled weight loss programs.[ref]

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Doses, side effects, and cautions if you currently have cancer:

Most glutamine supplements (as powder) have a 5g/day recommended dose. The taste is mildly sweet with just a slight sour aftertaste. I can detect it when I add it to coffee but not in herbal teas or a smoothie.

A study on the adverse effects of amino acid supplements showed that there is an absence of adverse events up to 14g/day.[ref]

Another study in older adults noted no adverse effects with a 12g/day oral dose for 60 days.[ref]

Glutamine can be converted to glutamate and can be used by certain types of cancer cells for growth. If you have cancer, be sure to talk with your doctor before taking any supplement, including l-glutamine. There are a lot of studies going on right now involving glutamine deprivation to starve cancer cells during cancer treatment. This isn’t a one-size-fits-all recommendation — different types of tumors react differently (some studies show glutamine helps reduce cancer mortality[ref]).

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Personal experience with l-glutamine:

After reading and writing about microplastics harming the mucosal barrier and how a thinning mucosal barrier can lead to autodigestion, I decided to try l-glutamine myself for the gut mucosal barrier benefits.

To be honest, I haven’t noticed anything from taking 5g/day for about two weeks…

(I didn’t have any ‘gut issues’ to begin with, so I’m not all that surprised by the lack of noticeable effects.)

L-glutamine could be doing wonders in the gut and protecting against microplastic translocation into the body, but I just don’t know.

So… I’ve ordered a microplastics blood test kit to get a current baseline, and then I’ll test again in three to six months. I’ll write more about the microplastics blood test kit experience in a few weeks, and will let you know what the followup test shows in a few months. Stay tuned!