Low L-glutamine levels may affect metabolism and gut health. Using supplements may help manage irritable bowel syndrome (IBS).

L-glutamine is a nonessential amino acid that people often simply call glutamine. It is essential for overall health. Glutamine is the most abundant amino acid in the body and essential for many bodily functions. People often use the terms glutamine and L-glutamine interchangeably, but they have different structures.

The body needs essential and nonessential amino acids to create various proteins. A nonessential amino acid is a protein that the body can produce. A person does not need to get it from food.

Some research suggests L-glutamine may help manage symptoms in people with IBS.

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The body needs protein for most functions, and amino acids are the basic building blocks of proteins.

L-glutamine is the most plentiful amino acid in the body and supports intestinal health. For this reason, it may help people with IBS.

What is IBS?

IBS refers to a group of symptoms that affect a person’s digestive system. It can cause the following symptoms:

Some research has suggested that taking glutamine supplements can help manage the symptoms of IBS.

How can you reduce bloating?

In the bowel, glutamine appears to contribute to the following functions

  • regulating the rate of cell growth in the intestine
  • maintaining the levels of certain proteins
  • modulating signaling in specific inflammatory pathways
  • preventing cell death and cellular stress

L-glutamine can also boost immune cell activity in the gut, helping prevent infection and inflammation and to soothe intestinal tissue.

L-glutamine deficiency can occur with:

L-glutamine helps people with IBS by working to protect the mucous membrane of the digestive system. The mucous membrane blocks bacterial infiltration during digestion.

L-glutamine supplements appear to be safe for most people, although some have experienced constipation and bloating.

However, supplements may not be suitable for those who have:

  • a sensitivity to monosodium glutamate
  • epilepsy
  • bipolar disorder
  • liver disease

They may also interfere with antiseizure medications.

Doctors sometimes prescribe L-glutamine for sickle cell disease under the name Endari. Endari can have the following adverse effects:

  • constipation
  • nausea
  • headache
  • pain in the abdomen, chest, back, or extremities
  • cough

Dietary sources can also boost L-glutamine levels.

In the United States, some research suggests that the most common dietary sources of glutamine include:

  • grains
  • dairy products
  • fish or poultry
  • red meats

Beans, lentils, and other high-protein foods can also help boost glutamine levels.

Other supplements that may benefit people with IBS include digestive enzymes. These can help the body break down foods into smaller molecules, making them easier to absorb.

Examples of digestive enzymes a person with IBS may take include the following:

  • Amylase: Helps break apart complex sugars in food.
  • Pepsin: Breaks down proteins found in meat, eggs, and dairy products.
  • Lipase: Breaks down complex fats molecules.
  • Lactase: Breaks down lactose, present in dairy products.
  • Trypsin: Breaks down several proteins to form amino acids.

Do digestive enzymes work for IBS?

At present, there is not enough scientific research to prove that L-glutamine improves the symptoms of IBS, but some evidence is emerging to support its use.

In 2019, a small study focused on 106 people with diarrhea-predominant IBS that had developed after an infection. After delivering 5 grams (g) per day of either L-glutamine or a placebo, the researchers assessed the participants’ symptoms according to a scale known as the Irritable Bowel Syndrome Severity Scoring System.

Results showed that 79.6% of people who used L-glutamine saw an improvement of at least 50 points on the scale, compared with 5.8% of those taking the placebo.

There were improvements in:

  • stool frequency
  • stool consistency
  • intestinal permeability

In a 2021 study, two groups of 22 people followed a FODMAP diet for 6 weeks, either with or without a daily supplement of 15 g of glutamine. They all had symptoms of IBS. There was a significantly higher improvement in scores among those taking the supplement compared with those following the diet alone.

While this suggests L-glutamine may help manage IBS symptoms, the researchers note that they need more studies to establish a suitable dose.

Plans are currently underway for clinical trials on the effect of glutamine on diverticulitis, an infection that can occur in the colon.

Some research suggests L-glutamine benefits intestinal health and may help people with IBS.

Anyone with IBS who is considering taking L-glutamine supplements should first speak with a doctor. If they use supplements, it is essential to follow the recommended dosage instructions and seek medical advice if any adverse effects occur.