A Complete Guide To L-Glutamine, From A Functional MD

As an integrative gastroenterologist, one of the most common questions I'm asked is: how do I support my gut?

While the question is a loaded one, it's also one of my favorite questions to answer. In fact, it's the reason I became a doctor in the first place—it opens the door for me to make a real and lasting impact on a patient's health. There are a variety of approaches for evaluation and management of gut health that can be taken depending on the particular person and their situation.

Glutamine is an amino acid1, aka a building block of protein. Protein is essential nutrient, necessary for the cells and muscles to carry out their functions.

L-glutamine supplements are becoming more popular by the day. They are mostly found in a powder form that you add to a glass of water or smoothie, but L-glutamine can also be ingested by way of supplement capsules.

According to a study published in the International Journal of Molecular Science, glutamine is one of the most common amino acids in the blood and cells, and it's a preferred source of energy for intestinal cells2. The authors also explain that glutamine supplementation can protect the lining of the bowel and help it keep a strong intestinal barrier, in addition to reducing intestinal permeability (i.e., leaky gut), enhancing immune cell function, and supporting the immune system while reducing the inflammatory response3.

As I mentioned before, L-glutamine has many reported benefits. One study suggested that taking a glutamine supplement may result in decreased muscle soreness after eccentric exercise5.

The amino acid can also be used by patients receiving treatment for head and neck cancer since it may reduce the incidence of painful swallowing and inflammation of the mouth.6 In this setting, the glutamine supplement is providing a protective coating to the mouth and esophagus.

Fatty liver is one of the most common conditions I see in my patients, and it's largely due to lifestyle and dietary patterns.

Another study published in the Journal of Clinical Investigation found mice who were given glutamine9 saw an increase in their immune response, and were less likely to experience reactivation of herpes infection. This research further supports the idea that glutamine can play a role in supporting the immune system.

The International Journal of Molecular Science study from before suggests that L-glutamine could block the activation of two pro-inflammatory mediators, and thereby reduce the expression of inflammatory cytokines. In other words, it may help reduce inflammation.

The same article reviewed other studies and suggested that glutamine supplementation, in general, seems to help regulate the growth of intestinal cells, maintain the gut's tight junctions11, influence inflammatory cascades, and protect against cell death and stresses.

While L-glutamine is an important amino acid when it comes to gut health2, those benefits have greater implications. More than 70% of our immune system lives in the gut. Therefore, autoimmune conditions (Hashimoto's thyroiditis, fibromyalgia, and many others) could potentially be influenced by glutamine supplementation.