Is glutamine (glutamine) recommended for Irritable Bowel Syndrome (IBS) mixed type?

Glutamine is Not Recommended for IBS Mixed Type

Based on current clinical guidelines, glutamine supplementation is not recommended for the management of mixed-type irritable bowel syndrome (IBS). The British Society of Gastroenterology guidelines and American Gastroenterological Association (AGA) guidelines do not include glutamine among their recommended first-line or second-line treatments for IBS 1.

Evidence-Based Treatment Options for IBS Mixed Type

First-Line Treatments

• Regular exercise - Strongly recommended despite weak evidence quality 1
• Dietary modifications - First-line dietary advice should be offered to all IBS patients 1
• Soluble fiber - Effective for global symptoms and abdominal pain; start with low dose (3-4 g/day) and increase gradually 1
• Low FODMAP diet - Effective as second-line dietary therapy, but implementation should be supervised by a trained dietitian 1
• Loperamide - Suggested by the AGA for IBS-D, can help with diarrhea symptoms but may cause constipation, abdominal pain, bloating, and nausea 1
• Certain antispasmodics - May be effective for global symptoms and abdominal pain, though evidence quality is very low 1

Second-Line Treatments

• Tricyclic antidepressants (TCAs) - Effective as gut-brain neuromodulators for global symptoms and abdominal pain; start at low dose (10 mg amitriptyline once daily) and titrate slowly 1
• Selective serotonin reuptake inhibitors (SSRIs) - The AGA suggests against using SSRIs for IBS patients, though the BSG notes they may be effective for global symptoms 1
• Eluxadoline - Efficacious for IBS-D in secondary care, but has contraindications 1

Glutamine Research in IBS

While glutamine is not included in major IBS treatment guidelines, there is limited research on its use:

1. A 2021 randomized controlled trial found that adding glutamine (15 g/day) to a low FODMAP diet showed superiority in reducing IBS symptom severity compared to low FODMAP diet alone 2. This study showed an 88% improvement rate in the glutamine group versus 60% in the control group.

2. A 2019 study specifically focused on post-infectious IBS-D showed that glutamine supplementation (5 g three times daily) significantly reduced symptoms and normalized intestinal permeability compared to placebo 3. However, this was limited to post-infectious IBS-D, not mixed-type IBS.

3. A systematic review of glutamine supplementation in inflammatory bowel disease (not IBS) found no significant effect on disease course, anthropometric measurements, intestinal permeability, disease activity, or biochemical parameters 4.

Clinical Approach to IBS Mixed Type

For IBS mixed type, follow this evidence-based algorithm:

1. Start with lifestyle modifications:

   • Regular exercise
   • First-line dietary advice
   • Soluble fiber supplementation (starting at 3-4 g/day)

2. If symptoms persist, consider:

   • Low FODMAP diet (supervised by a dietitian)
   • Antispasmodics for pain and cramping

3. For second-line therapy:

   • TCAs (starting at 10 mg amitriptyline daily)
   • Loperamide for diarrhea predominant phases

Important Caveats

• The evidence for glutamine in IBS is limited and not included in major clinical guidelines.
• The positive results from the 2021 study combining glutamine with low FODMAP diet 2 and the 2019 study on post-infectious IBS-D 3 warrant further investigation but are not sufficient to recommend glutamine as standard therapy.
• When treating IBS mixed type, consider the predominant symptom (constipation vs. diarrhea) when selecting medications.
• Avoid insoluble fiber as it may exacerbate symptoms 1.
• Food elimination diets based on IgG antibodies and gluten-free diets are not recommended unless celiac disease is present 1.

In conclusion, while emerging research on glutamine shows some promise, particularly in combination with a low FODMAP diet or for post-infectious IBS-D, current clinical guidelines do not support its routine use in mixed-type IBS management.