Does L-Glutamine Help IBS? A Registered Dietitian Nutritionist Explains the Evidence

L-glutamine is the most abundant amino acid in your body and is necessary to build proteins and maintain various aspects of health.

Sometimes referred to as glutamine, L-glutamine is a nonessential amino acid, meaning your body can make it on its own. However, it’s still important to consume L-glutamine through foods or supplements.

Research shows that L-glutamine supports metabolism and immunity and may also benefit gut health. Some studies also show that L-glutamine may help alleviate symptoms of irritable bowel syndrome (IBS).

 

L-Glutamine May Help IBS

Some evidence indicates that L-glutamine supplementation may improve IBS symptoms.

However, research in this area is limited because only a few human trials are available.

In one small study, adults with diarrhea-predominant IBS (also known as IBS-D) were randomized to take either 15 grams (g) of glutamine or a placebo every day for eight weeks.

Almost 80% of those who took glutamine improved their IBS Severity Scoring System (IBS-SS) scores by at least 50 points.

Glutamine was also associated with improved daily bowel movement frequency, abdominal pain, and quality of life.

In another study, adults with IBS followed a low FODMAP diet with or without glutamine supplementation for six weeks.

Those who followed the diet and took daily glutamine (15 g per day) had more significant improvements in IBS symptoms than those who only followed the low FODMAP diet.

Despite these positive results, both studies had short duration times and didn’t cover all types of IBS.

More research is necessary to both strengthen this evidence and reach a better understanding of how L-glutamine may support people with IBS.

 

What Is IBS?

IBS is a chronic condition that affects the digestive system. Diagnosing it can be challenging because the symptoms may vary greatly from person to person.

The National Institute of Diabetes and Digestive and Kidney Diseases defines IBS as a group of symptoms that occur together.

These symptoms most often include abdominal pain as well as changes in bowel movements (constipation and/or diarrhea).

To diagnose IBS, a healthcare provider may order specific lab tests to rule out other diseases or perform a colonoscopy.

IBS typically occurs without any noticeable damage to the digestive tract.

Researchers still aren’t sure what causes IBS. However, some evidence points to the cause of IBS as a disruption of the brain-gut axis.

The brain-gut axis plays a significant role in digestion, including gastrointestinal motility (movements of digestion) and secretion of digestive enzymes.

Certain foods may trigger IBS symptoms in those who have the condition.

People with IBS may follow specific diets depending on their food triggers. Common diets recommended to people with IBS are a gluten-free diet and a low FODMAP diet.

It’s important to briefly note that IBS is different from IBD (inflammatory bowel disease).

Though both conditions are chronic, IBD often results in inflammation or damage to the gastrointestinal tract.

The two most common types of IBD are Crohn’s disease and ulcerative colitis.

Like IBS, IBD is thought to be caused by both genetic and environmental factors, but more research is necessary.

 

When Should You Take L-Glutamine?

A healthcare provider may recommend taking L-glutamine for specific health conditions or if you have a deficiency.

L-glutamine may be recommended for the following:

Although your body can make glutamine, you can also become deficient in the amino acid.

Glutamine deficiency may occur due to trauma or specific conditions in which red blood cells are destroyed. A glutamine deficiency typically requires supplementation.

To ensure proper diagnosis and treatment, consult a healthcare provider before taking L-glutamine for a suspected deficiency.

 

What Are the Risks of Taking L-Glutamine?

As with any dietary supplement, taking L-glutamine may involve some risks. Possible risks include allergies, interactions, side effects, and other precautions.

• Allergic reactions: Although rare, some people may be allergic to L-glutamine. Seek immediate medical attention if you have signs of a severe allergic reaction to L-glutamine, including itching, hives, and shortness of breath.
• Interactions: L-glutamine may lower blood sugar and alter how insulin works in your body. People taking diabetes medications should talk with a healthcare provider before using L-glutamine. There is also evidence that glutamine increases arginine, another amino acid, in your body.
• Side effects: Some people experience side effects when taking L-glutamine supplements. Possible side effects of L-glutamine include constipation, nausea, headache, abdominal pain, cough, and pain in your back, legs, feet, hands, or arms.
• Other precautions: Talk with a healthcare provider before taking L-glutamine if you have any health conditions. People who are pregnant or breastfeeding may need to take extra precautions before using L-glutamine. There is also some concern that L-glutamine may make liver disease worse, but more research is necessary.

If you have any health conditions, take other supplements, or take prescription medications, talk with your healthcare provider to ensure that L-glutamine is safe for you.

 

What Foods Have L-Glutamine?

Glutamine is an amino acid found in many protein foods, including plant—and animal-based proteins.

Adults typically consume 3 to 6 g of glutamine daily through food.

For healthy people, a food-first approach is recommended for getting enough glutamine.

Sources of glutamine include:

• Red meat
• Poultry
• Fish
• Dairy products
• Grains

Animal products are thought to contain more glutamine than plant-based foods. However, very little research has looked into the exact amounts of glutamine in foods.

According to one study, the glutamine content of specific foods (per 100 g) is:

There is no recommended daily intake amount for glutamine.

Most healthy people get all the glutamine they need from their diet and their body’s natural synthesis of glutamine.

However, a glutamine supplement may be recommended for specific health conditions.

 

What Else May Help IBS Symptoms?

L-glutamine may not be the only integrative treatment for IBS. Other supplements and health approaches have been studied for their potential benefits for people with IBS, including:

• Peppermint oil: Research shows that peppermint oil may help relieve IBS-related pain. According to one review, peppermint oil was more effective than a placebo at reducing abdominal pain and other IBS symptoms. However, the long-term benefits of using peppermint for IBS are still unknown, so more research is necessary.
• Probiotics: For people with IBS, probiotics may balance the gut microbiome and help manage symptoms like pain and bloating. One review found that multi-strain probiotics may work better than single-strain probiotic supplements when alleviating symptoms. Additional research would be beneficial.
• Mind-body medicine: Some evidence indicates that specific mind-body medicine techniques may help reduce the severity of IBS symptoms. Mind-body interventions, such as yoga and cognitive behavioral therapy (CBT), are thought to reduce stress and improve symptoms and quality of life for people with IBS and other conditions.
• Diet changes: You may be able to manage IBS by making a few changes to your diet. Specific diets like high-fiber, low-FODMAP, or gluten-free diets may help improve IBS. Additionally, an elimination diet in which foods are slowly removed and then reintroduced may help you pinpoint specific IBS triggers (but only do this under the guidance of a healthcare provider).

For additional guidance on how to manage IBS, talk with a healthcare provider.

 

Summary

L-glutamine is an amino acid your body needs for specific functions, like building proteins. It may also help manage IBS, a health condition characterized by changes in bowel habits, bloating, and abdominal pain.

Some evidence indicates that L-glutamine supplements may help reduce specific IBS symptoms, but more research is necessary overall.

L-glutamine supplements are generally considered safe, but side effects, interactions, and other adverse events are also possible.

Your body can make L-glutamine and get it through various foods, including animal-based foods and grains.

There are many other ways to manage IBS, and a healthcare provider can help you choose the best treatment.