Irritable bowel syndrome (IBS) is a complex, painful digestive health condition that impacts about 40-45 million Americans. The cause of IBS is likely different for different people. There is much about IBS that simply remains unknown.
Most experts believe that alterations in our gut microbes play a role in the pathogenesis of IBS. An association with small intestinal bacterial overgrowth (SIBO) occurs in a subset of IBS patients. Other factors linked with the onset of IBS include changes in gut motility, food borne illness, alteration in the gut-brain axis (a bi-directional communication pathway between the gut and the brain).
Acute GI infections increases the risk of post-infectious IBS (7-fold) and use of systemic antibiotic is also associated with an increased risk of developing IBS.
Changes in our gut microbes are thought to:
- Increase gut permeability
- Alter the motility of the intestine (methane gas production by microbes is associated with constipation, or slowing down gut motility).
- Increase sensitivity of the gut perhaps due to increase in histamine or LPS (lipopolysaccharide), a bacterial endotoxin–both gut microbial derived metabolites.
With this in mind, much research has been devoted to therapies to address the gut microbiome in individuals with IBS from the non-absorbable antibiotic rifaximin, to prebiotics and probiotic therapies. The low FODMAP diet is a nutritional approach, shown to manage symptoms in 50-70% of individuals with IBS, also likely a gut microbiome directed therapy. FODMAPs are fast food for our gut microbes. Research shows that the low FODMAP elimination diet changes the gut microbial community. The long-term impact of these changes, which include change in stool pH (a measure of the acidity of the stool–the low FODMAP diet makes stool slightly less acidic), increase in gut microbial diversity, reduction in probiotic, bifidobacteria, is unknown. Assessing these gut microbial effects in an individual that has undergone the re-introduction FODMAP diet has not been done at this time (to my knowledge).
To recap, some treatments geared toward gut microbiome in individuals with IBS include:
- Rifaximin -non-absorbable antibiotic that is FDA approved for IBS-D. Commonly used off label for SIBO.
- Syn-010-a modified release statin drug derivative shown to reduce methane levels by blocking cell membrane synthesis M. Smithii, a common GI microbe, and primary producer of methane production in the gut. (Not available to the consumer at this time).
- Prebiotics & Probiotics: Discussed previously on my blog, here.
- Diet: The low FODMAP diet has the best evidence for IBS symptom management but there are concerns over the level of restriction of this diet plan. I believe the low FODMAP diet is just one tool in the GI dietitian’s tool box. It should be utilized with care. The low FODMAP diet can meet nutritional needs but this likely warrants the guidance of a specialized GI dietitian.
I will leave you with this quote from William Chey, gastroenterologist and IBS expert, “The low FODMAP diet is now recognized as an effective treatment for IBS. However, the low FODMAP diet is not the solution for all IBS patients. This should come as no surprise given the diverse causes and symptoms of IBS. Creative thinking, experience, and hard work will help new diet therapies transform from interesting concepts to evidence-based treatment options. As every novel is composed of different chapters, the low FODMAP diet represents a compelling first chapter, one which has captivated providers and patients alike. In the years to come, other chapters will take shape and science will write their stories.”
Dr. Chey’s team at Michigan Medicine is one of the leading diet and nutrition clinical research groups in the US. Their research mantra is to improve the lives of patients with IBS and other functional GI disorders through diet and nutrition.
Here is what Dr. Chey’s and his team are working on at present:
- Determining the role of the low FODMAP diet for abdominal pain and bloating in patients with IBS and constipation
- Conducting studies to determine the most efficient and effective means of reintroducing FODMAPs in patients who improve after excluding FODMAPs from the diet
- Identifying biomarkers which will help health care providers to determine which IBS patients are most likely to improve with the low FODMAP diet
- Conducting a clinical trial to compare the effectiveness of psyllium, prunes, and kiwi as treatments for chronic constipation. This will be the first trial to evaluate kiwi for constipation in the US.
- Determining whether breath testing identifies IBS patients who are more likely to improve with the non-absorbed antibiotic rifaximin
- Determine the best test to identify patients with intestinal enzyme deficiencies – an enzyme called sucrase isolmaltase is responsible for breaking down table sugar and starch. Lack of this enzyme can cause symptoms which are identical to lactose intolerance and may be an unrecognized cause of IBS.
- Testing a novel IgG antibody test which can identify patients with food sensitivities.
- Assisting in the development of a novel prebiotic which alters the gut microbiome in a way that improves the symptoms of lactose intolerance.
How exciting is this? I have included Dr. William Chey’s group as one of two research groups to donate through the #IBelieveinyourStory campaign.
Please consider being part of the change. Together, we WILL change the future of IBS.
Donations for Dr. William Chey’s lab can be made here.