The chances that either you or someone you know experiences some form of IBS or SIBO symptoms, whether in the form of bloating, gas, constipation, diarrhoea, reflux or nausea, are pretty high in these modern times. Mostly, though, the mystery surrounding its solution or how it started can remain unsolved. This mystery is what we are here to explore in this article.
Common frustrations from patients with a long history of IBS diagnoses from various specialists and practitioners is that they don’t have a clear insight into exactly how it happened and, worse still, a lack of precise tools to help get long-term relief of the symptoms. A quick teaser, SIBO may be the breakthrough that clears up this mystery of IBS for many people, including those people you know suffering today.
I’ve seen patients present with IBS diagnoses from their doctor and SIBO from their Dr Google consultation, often with some confusion about how they relate to each other. The answer is like the chicken and egg problem. One can cause the other, or vice versa. First, let’s deconstruct the nuance of both to understand better how they’re connected.
What is Irritable Bowel Syndrome (IBS)?
A simple, concise definition of IBS is a chronic functional disorder of the colon and large intestine defined by disturbed bowel habits, abdominal pain, and discomfort without an organic and identifiable cause.[1]
As with other syndromes, the understanding of IBS has evolved and is diagnosed under three more specific subtypes:
- IBS – C (IBS with constipation)
- IBS – D (IBS with diarrhoea)
- IBS – M (IBS with mixed bowel patterns also referred to IBS – A for alternating)
Interestingly, women tend to present more often with IBS – C and men, IBS – D.[2]
From my own clinical experience, I can tell you that patients with IBS often present with a complex and unique collection of symptoms. For the sake of this explanation, though, some of the standard and often most distressing symptoms are urgencies to go to the toilet, abdominal and muscle pain, straining, bloating and fatigue.[3]
What can be most frustrating is the nature in which these presenting symptoms can alternate. The abdominal pain can sometimes travel to different parts of the abdomen for no reason, sometimes it’s lower left, sometimes lower right, and there seems no way to connect the dots. This erratic presentation can be highly unsettling for those who experience it. The reason for this is down to how many different activating factors there may be.
Some of the reasons behind the genesis of IBS may be the following:[4]
- Altered motility within the gastrointestinal system (motility is the ability your digestive system has to move food from one organ of the digestion to another and has a considerable influence on your bowel patterns)
- Reactions to a previous infection; for example, E.coli infection
- Brain-gut interactions (it’s not well-known that IBS-C sufferers often have a lower level of serotonin. Conversely, IBS-D sufferers have higher levels of serotonin)[5] [6]
- Alterations in the bacterial environment within the digestion or microbiome.
- Bacterial overgrowth (what a moment could that be SIBO?)
- Food sensitivity (over 70% of IBS sufferers find their symptoms improve with a low FODMAP diet)[7]
- Inflammation within the intestinal tract
A more common characteristic of IBS, at least for the patients present in the clinic, is the chronic nature or how long they’ve been suffering. On average, I see patients who have been dealing with these issues for at least three years before seeking help. Three years could be considered a small amount of time for those seeking and trying different treatment methods over time.
It can be a frustrating and challenging journey for those in this situation, but it seems that small intestinal bacterial overgrowth may be the answer to at least some of the cases.
What is Small Intestinal Bacterial Overgrowth (SIBO)?
SIBO occurs when excessive numbers of bacteria in the small bowel (also known as the small intestine) cause gastrointestinal (GI) symptoms. Commonly, the bacteria found in excess include gram-negative bacteria (bacteria without a cell wall) that ferment poorly digested carbohydrates producing gas. [8]
As the small intestine is a critical site for nutrient absorption, symptoms of SIBO can often present as a result of malabsorption caused by the bacterial fermentation mentioned above. It’s necessary to define what malabsorption means in this case. It doesn’t mean you are not getting your vitamins and minerals (although in very severe cases, some vitamin B12 and iron deficiencies have been seen in SIBO). More so that your carbohydrates may not be completely absorbing, leaving some remaining in often the final part of the small intestine to ferment. This fermentation then creates the gas that can drive the bloating, fullness and distension.
Evidence suggests that the typical symptoms described in patients with a positive SIBO test are as follows:[9]
- Abdominal Pain
- Diarrhoea, constipation or both
- Nausea
- Bloating
- Flatulence
- Fullness or distension
- Fatigue
- Poor concentration
It’s hard not to see the similarities between the proposed symptoms of SIBO and the ones associated with IBS, and studies are connecting the two. [10] [11] Further studies can consolidate this relationship, but current estimates suggest that up to 78% of patients with IBS suffer from SIBO.[12] At a clinical level, though, many people with IBS are going through the SIBO breath test and treatment process seeing results they didn’t think possible.
Diminished stomach acid and poor digestive function are potential origins of IBS and SIBO, and one of the world’s most over-used and prescribed drugs could make it worse.
In other articles, we have discussed the connection between SIBO and ineffective digestion. As well as this, we see diminished or low stomach acid as causative factors for IBS. Correction of low stomach acid, or what’s commonly known as hypochlorhydria, can be a critical part of the longer-term recovery from IBS post shorter-term treatments with diet.
Chronic, moderate exposure to stress is often a consideration in developing low stomach acid over time. Still, it’s essential to assess the role of proton-pump inhibitors (PPIs) in the origin of symptoms. Especially if there has been a history of their use in the past.
As with most commonly prescribed drugs, PPIs play a role in managing people’s symptoms in the short term so that things don’t become worse. Unfortunately, their overuse and over-prescription see not only a lowering of the all-important acidity of the gastric juice but also a significant change in the bacterial diversity of your microbiome.[13]
It’s becoming clear that the connection between IBS and SIBO is easy to see but difficult to differentiate between due to the overlap of activating factors. PPIs are involved in the development of SIBO.[14] Still, they have evidence in actually helping IBS [15] in some cases, which means that adequately assessing each situation on a case-by-case basis is still highly critical to a successful outcome. This need for individualisation is where functional testing can come in.
SIBO Breath testing and comprehensive stool testing can help to create a more focused treatment for IBS symptoms.
Fortunately, in the case of digestive problems, the “test don’t guess” mentality clears a lot of the confusion around the origin of either SIBO or IBS. Studies confirm that correction of abnormal readings in a lactulose breath test correlates with symptom improvement in IBS cases.[16] Further studies imply that the same breath test may be the best marker to use for bacterial disturbances seen in IBS cases.[17]
A SIBO breath test can indicate dominance in particular forms of bacteria, either methane or hydrogen-forming, which can directly influence the type of herbal or antibiotic treatment used to rebalance the overgrowth and offer insights into how things kicked off in the first place. For example, a positive baseline in the lactulose version of the SIBO breath test can suggest that IBS-D sufferers may have a better response to a commonly used antibiotic treatment called rifaximin.[18] These studies nearly always prove valid in practice, highlighting how much more focused and expedited things can get now with the luxury of testing.
A comprehensive stool exam such as the GI360 or GI-Map can go into a lot more detail regarding the imbalance of the microbiome. This test assesses both probiotic and prebiotic status, essential functional indicators such as nutrient absorption markers like the enzyme elastase, pointing to hydrochloric acid status, and insights into carbohydrate and fat absorption, amongst a wide range of other features such inflammation assessment, gut-associated immunity and the presence of candida and parasites. All these features offer clarity on how diet and accessory treatments such as pancreatic enzymes, postbiotics and diet can assist in achieving effective treatment.
So, is there a connection between Irritable Bowel Syndrome (IBS) and Small Intestinal Bacterial Overgrowth (SIBO)?
It’s fair to say the answer is a resounding yes. Although, as you might have found in reading this article, the definitions of IBS and SIBO are nuanced and hard to differentiate between in many cases. There are many crossover symptoms, such as bloating, bowel irregularities, pain, nausea and discomfort. Yet, initial research into the connection between IBS and SIBO has brought a new way of educating people about what’s going on and how they might help their issue.
This new understanding is leading most practitioners, including myself, to begin to use the term “SIBO” more often as a way of explaining the broader diagnosis of IBS or, at the very least, how it’s a sustaining or excitatory factor.
As our understanding of how testing and treatment can become more effective at keeping things better, it’s the patient (hey you!) that hopefully gets to benefit more than anyone. This new way of presenting things is where the connection between IBS and SIBO can become an absolute godsend for chronic IBS sufferers. It creates a pathway to action that can offer a higher level of potential for a successful outcome. In some cases, it ends years of the daily rollercoaster of IBS symptoms that can be debilitating and frustrating with no end in sight.
References
[1] Saha L. Irritable bowel syndrome: pathogenesis, diagnosis, treatment, and evidence-based medicine. World J Gastroenterol. 2014;20(22):6759-6773. doi:10.3748/wjg.v20.i22.6759
[2] Lovell RM, Ford AC. Effect of gender on prevalence of irritable bowel syndrome in the community: systematic review and meta-analysis. Am J Gastroenterol. 2012;107(7):991-1000. doi:10.1038/ajg.2012.131
[3] Saha L. Irritable bowel syndrome: pathogenesis, diagnosis, treatment, and evidence-based medicine. World J Gastroenterol. 2014;20(22):6759-6773. doi:10.3748/wjg.v20.i22.6759
[4] Occhipinti K, Smith JW. Irritable bowel syndrome: a review and update. Clin Colon Rectal Surg. 2012;25(1):46-52. doi:10.1055/s-0032-1301759
[5] Derbyshire SW. A systematic review of neuroimaging data during visceral stimulation. Am J Gastroenterol. 2003;98(1):12-20. doi:10.1111/j.1572-0241.2003.07168.x
[6] Houghton LA, Atkinson W, Whitaker RP, Whorwell PJ, Rimmer MJ. Increased platelet depleted plasma 5-hydroxytryptamine concentration following meal ingestion in symptomatic female subjects with diarrhoea predominant irritable bowel syndrome. Gut. 2003;52(5):663-670. doi:10.1136/gut.52.5.663
[7] Marsh A, Eslick EM, Eslick GD. Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and meta-analysis. Eur J Nutr. 2016;55(3):897-906. doi:10.1007/s00394-015-0922-1
[8] Sachdev AH, Pimentel M. Antibiotics for irritable bowel syndrome: rationale and current evidence. Curr Gastroenterol Rep. 2012;14(5):439-445. doi:10.1007/s11894-012-0284-2
[9] Pimentel M, Saad RJ, Long MD, Rao SSC. ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth. Am J Gastroenterol. 2020;115(2):165-178. doi:10.14309/ajg.0000000000000501
More references!
[10] Pimentel M. The prevalence of small intestinal bacterial overgrowth in irritable bowel syndrome: IBS vs healthy controls (not historical definitions). Gut 2008;57:1334–5.
[11] Majewski M, McCallum RW. Results of small intestinal bacterial overgrowth testing in irritable bowel syndrome patients: Clinical profiles and effects of antibiotic trial. Adv Med Sci 2007;52:139–42.
[12] Shah ED, Basseri RJ, Chong K, et al. Abnormal breath testing in IBS: A meta-analysis. Dig Dis Sci 2010;55:2441–9.
[13] Bruno G, Zaccari P, Rocco G, et al. Proton pump inhibitors and dysbiosis: Current knowledge and aspects to be clarified. World J Gastroenterol. 2019;25(22):2706-2719. doi:10.3748/wjg.v25.i22.2706
[14] Lo WK, Chan WW. Proton pump inhibitor use and the risk of small intestinal bacterial overgrowth: a meta-analysis. Clin Gastroenterol Hepatol. 2013;11(5):483-490. doi:10.1016/j.cgh.2012.12.011
[15] Mönnikes H, Schwan T, van Rensburg C, et al. Randomised clinical trial: sustained response to PPI treatment of symptoms resembling functional dyspepsia and irritable bowel syndrome in patients suffering from an overlap with erosive gastro-oesophageal reflux disease. Aliment Pharmacol Ther. 2012;35(11):1279-1289. doi:10.1111/j.1365-2036.2012.05085.x
[16] Pimentel M, Chow EJ, Lin HC. Normalization of lactulose breath testing correlates with symptom improvement in irritable bowel syndrome. a double-blind, randomized, placebo-controlled study. Am J Gastroenterol. 2003;98(2):412-419. doi:10.1111/j.1572-0241.2003.07234.x
[17] Shah ED, Basseri RJ, Chong K, Pimentel M. Abnormal breath testing in IBS: a meta-analysis. Dig Dis Sci. 2010;55(9):2441-2449. doi:10.1007/s10620-010-1276-4
[18] Rezaie A, Heimanson Z, McCallum R, Pimentel M. Lactulose Breath Testing as a Predictor of Response to Rifaximin in Patients With Irritable Bowel Syndrome With Diarrhea. Am J Gastroenterol. 2019;114(12):1886-1893. doi:10.14309/ajg.0000000000000444
