Is It Good To Take L-Glutamine For IBS

The body produces its own essential and non-essential amino acids to maintain proper gut health. One of the critical non-essential amino acids is L-glutamine. However, some individuals have deficient amounts of the amino acid, requiring them to increase their glutamine intake to manage intestinal health, especially in persons with IBS (irritable bowel syndrome).

Oral glutamine supplementation has been touted as an effective treatment for IBS symptoms. But does it really work for IBS? This article provides the answer to that question and other valuable insights into IBS and L-glutamine.  

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IBS prevalence in the US

The International Foundation for Gastrointestinal Disorders (IFFGD)¹ estimates that about 25 to 45 million Americans suffer from IBS, with females reporting IBS symptoms twice as often as males. Approximately 35–40% of individuals with IBS in the US are men and 60–65% are women. 

Those numbers indicate that IBS is a significant health issue among women. The condition notably increases the risk of unnecessary abdominal and extra-abdominal surgery among IBS patients. For instance, the chances of female IBS patients having a hysterectomy or ovarian surgery are as high as 47–55%. 

Understanding IBS

IBS, or irritable bowel syndrome, is a condition that affects the digestive system, particularly the large intestine. It's a group of symptoms that occur simultaneously, causing several digestive issues, such as cramps, abdominal pain, bloating, gas, diarrhea, or constipation.

IBS is a chronic disorder, and the symptoms occur intermittently for days, weeks, or months and can significantly affect your everyday life. Thus, patients must manage it in the long term. 

Only a small number of patients report severe signs and symptoms, which they can manage by simply being watchful of their diets, stress levels, and lifestyle. However, severe symptoms are treated with medication and counseling. While IBS increases the risk for surgery,² it doesn't cause visible signs of damage to bowel tissues or the digestive tract and doesn’t increase the risk of colorectal cancer.  

Signs and symptoms of IBS

People with IBS typically experience the following signs and symptoms:

  • Abdominal pain

  • Changes in bowel movements, resulting in diarrhea, constipation, or both

  • Bloating

  • The sensation that you haven't finished your bowel movements

  • Traces of white mucus in your stool

  • Women with IBS experience more of these symptoms during their periods.

What causes IBS?

Unlike an infection or tumor, IBS is what medical professionals refer to as a functional disorder — a health issue with no specific or identifiable cause. That's because there are usually no visible diseases or damage to their digestive systems. But as scientific research advances, doctors are beginning to discover physical or biochemical explanations for the causes of functional disorders like IBS. 

IBS can be attributed to various causes, including:

Abnormalities in nerves

According to a health report by The New York Times,³ the prevailing theory behind IBS is that abnormalities in the overly sensitive nerves in the gastrointestinal (GI) tract send distress signals to the brain, causing IBS patients to feel greater discomfort, pain, or malfunction when the bowel stretches from gas or stool. 

Allergic reactions in the gut

IBS can also be triggered by an allergic reaction in the GI tract, disrupting the cells forming the protective layer lining the bowel. These cells prevent the absorption of allergy-inducing foods. Once the barrier is penetrated, an individual can become intolerant to some foods that previously caused them no problems.

The resulting immune response causes muscle contractions in the colon, bloating, diarrhea, and abdominal pain.

Severe infection

A person can also develop IBS following repeated and severe bouts of diarrhea caused by a bacterium or virus. The condition may also be associated with excess bacteria or bacterial overgrowth in the intestines. 

Changes in digestive microbes

Changes in bacteria, viruses, and fungi that normally reside in the intestines and play a critical role in maintaining gut health can cause IBS. The gut microbes in people with IBS differ significantly from those in healthy individuals. 

Diagnosis of IBS

The diagnostic techniques for IBS have advanced since the first criterion was established in 1979. Some of these changes included the Rome I criterion, which was later revised to Rome II, and the last review resulted in the Rome III criteria. Doctors can use Rome II and Rome III criteria, which have been established to offer better diagnostic results. 

When following the Rome II technique, a doctor will accurately diagnose IBS if the patient experiences abdominal pain and discomfort over 12 weeks, which need not be consecutive, during the past 12 months. 

The Rome III diagnostic technique specifies that a patient must experience abdominal pain and discomfort intermittently at least three days per month in the past three months. Whether the doctor chooses to use Rome II or Rome III criteria, the abdominal pain and discomfort must be characterized by two or more of the following features:

  • Improvement in defecation

  • A change in stool consistency

  • A change in stool frequency

Nonetheless, the American College of Gastroenterology (ACG) stated that relying on symptom-based diagnostics may not offer accurate IBS diagnosis. The ACG thus defines IBS as abdominal pain and discomfort associated with changes in bowel habits for at least three months. 

Gastroenterologists today rely on the known causes and symptoms of IBS to provide more accurate diagnoses. Some of these symptoms include:

  • Brain-gut interactions

  • Food sensitivity

  • Bacterial overgrowth

  • Gut reaction to a past infection

  • Intestinal inflammation

  • Gastrointestinal motility

  • Visceral hypersensitivity

  • Changes in fecal microbes

Treatment and management of IBS using L-glutamine

Although the causes of IBS are not well-known, recent studies⁴ have shown that dietary intolerance, increased intestinal permeability, and changes in gut microbes expose people to potential risks. Additionally, diets low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) are known to improve GI symptoms among IBS patients. 

However, these foods can only reduce pain and bloating, with no efficacy on stool consistency and frequency. There's still a need for other effective IBS management strategies for stool consistency and frequency. That's where L-glutamine comes into play. 

Glutamine is a non-essential amino acid that the body produces naturally to maintain gut health. But as we mentioned earlier, sometimes the body doesn't produce sufficient L-glutamine, resulting in a deficiency. Usually, L-glutamine deficiency⁵ occurs due to various reasons:

  • Trauma

  • Shock and extreme stress

  • Intense exercise

  • Immuno-deficiency disorders, such as HIV/AIDS

  • Chronic GI disorders, such as Crohn's disease, inflammatory bowel disease, and eosinophilic esophagitis

  • Low L-glutamine in the diet

Therefore, increasing the oral intake of L-glutamine can lead to better bowel health. The amino acid is a preferred energy source for cells with a high turnover rate, such as enterocytes – these are the cells lining the intestines. Glutamine is known to reduce IBS in various ways, including:

  • Accelerating enterocyte proliferation

  • Regulating tight junction (TJ) proteins⁶

  • Suppressing nervous pathways that send inflammation signals 

Does glutamine work for IBS?

Intestinal permeability in patients with diarrhea-predominant IBS (IBS-D) is closely associated with a shortfall in glutamine in the body. Experimental evidence shows that glutamine supplementation can significantly reduce intestinal permeability.

Moreover, L-glutamine supplementation can alter the digestive microenvironment and optimize intestinal bacteria's utilization and metabolism of amino acids, thus changing the composition of intestinal microbiota. This action has a high potential for improving constipation and bowel function. 

Based on the findings, it's rational to hypothesize that the co-administration of a low FODMAP diet and oral glutamine supplementation can reduce the signs and symptoms and improve the quality of life of IBS patients than eating low FODMAP foods alone. 

Another study⁷ also showed promising results of using dietary glutamine supplements for infection-caused IBS-D. It was a randomized, double-blind, placebo-controlled trial that investigated the efficacy and safety of oral glutamine supplementation in IBS-D patients with severe intestinal permeability after a GI infection. 

The 8-week study sampled a population of 54 glutamine and 52 placebo subjects. The result was incredible. There was a significant occurrence of the primary endpoint, with 43 (79.6%) glutamine subjects reporting improvements in their IBS-D, against only 3 (5.8%) in the placebo group who reported relief — a 14-fold difference.

Additionally, L-glutamine also reduced other IBS-D signs and symptoms, including:

  • Daily bowel movement frequency

  • Intestinal permeability

  • Intestinal hyperpermeability

Side effects L-glutamine

While glutamine is considered safe for most IBS patients, others suffer side effects and must avoid it. Examples of conditions that render you L-glutamine-intolerant include Reye's syndrome, kidney disease, bipolar disorder, and any other condition that causes swelling of the brain or liver. 

Additionally, other studies⁸ have shown that some specific tumor cells feed off glutamine to accelerate their spread. Therefore, your doctor will recommend that you avoid taking glutamine if you have, or are at risk of, cancer.

Other individuals are allergic to L-glutamine. Suppose an allergic person takes the amino acid. In that case, the allergic reaction can cause nausea, vomiting, joint pain, and hives. 

It is critical to seek immediate medical attention if you or someone you know experiences any side effects after taking L-glutamine. 

Other treatment options for IBS

Gastroenterologists use medical and other alternative therapies to treat IBS symptoms. Some of these treatment options include the following:

Dietary and lifestyle changes

Your diet may bring relief to repeated bouts of IBS symptoms. Your doctor may recommend the following dietary changes:

  • Eat more fiber foods, such as avocados, apples, bananas, carrots, broccoli, artichoke, etc.

  • Avoid gluten foods like bread, grains and cereals, bread, pastries, french fries, soups and gravies, stuffing, salad dressings, vinegar, pasta, and noodles, etc. 

  • Adhere to a low FODMAP diet

When it comes to lifestyle changes that reduce IBS symptoms, your physician may advise you to:

  • Exercise more

  • Get enough sleep

  • Reduce stressful life situations


Probiotics are live microorganisms – mostly bacteria or yeasts – that are similar to the microbes found in the digestive system. These good bacteria help your digestive system suppress the increase in bad bacteria in the large intestine, and researchers⁹ have discovered that probiotics can relieve IBS symptoms.

You can get probiotics by consuming various foods, such as yogurt and buttermilk. However, it's critical to check the label for "live and active cultures."

It would also be best to consult your doctor before using probiotics or other alternative therapy. They'll guide you on how much probiotics you should take and for how long.

Mental health therapies

Your physician can also recommend mental health therapies to treat IBS symptoms. Some of these therapies include:

  • Cognitive behavior therapy, which focuses on helping patients change their thoughts and behavior patterns are known to trigger IBS symptoms

  • Gut-directed hypnotherapy, where your doctor uses hypnosis — a trance-like therapy that helps you relax and focus your thoughts — to relieve IBS symptoms

  • Relaxation techniques that can help you relax your muscles to alleviate stress

The lowdown

The high prevalence of irritable bowel syndrome (IBS) in the US results in a significant economic and psychosocial burden. IBS patients with debilitating symptoms are usually told it's all in their heads because the condition has long been known as a functional disorder.

But researchers have discovered measurable physical and biochemical causes of IBS, allowing doctors to accurately diagnose the condition and recommend the most effective treatment option. 

Administering L-glutamine can significantly reduce abdominal pain and discomfort associated with IBS. It also improves stool consistency and frequency as well as intestinal permeability. Still, co-administering glutamine and a low FODMAP diet can improve the quality of life in patients with IBS more effectively than relying on a low FODMAP diet alone. 

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