This article was originally published in 2015 and has been updated in November 2018 to reflect the latest research.
Do you have gas, bloating, abdominal pain, and stool issues? Up to 20 percent of the U.S. population suffers from irritable bowel syndrome (IBS), a condition that adversely affects daily life. Instead of digging deeper to identify the underlying cause(s), conventional medicine typically offers medications to suppress gut symptoms. Read on to learn about five lesser-known causes of IBS that you may not be looking for.
Irritable bowel syndrome doesn’t have to be a lifelong sentence. Learn about five underlying causes of IBS you might not be looking for to help heal the gut from the inside out.
How Doctors Diagnose IBS
IBS is the most common functional gastrointestinal disorder. Yet it’s poorly understood—not only by those who suffer from it but also by many clinicians who try to treat it. (1) Symptoms of IBS include gas, bloating, and abdominal pain, accompanied predominantly by constipation, diarrhea, or both. Those afflicted report lower quality of life and activity levels and call in sick twice as often as the general population. (2) Depression and anxiety often accompany IBS, most likely through the gut–brain axis connection between the enteric nervous system of the GI tract and the central nervous system.
Over the years, diagnostic criteria have evolved, but IBS is now generally defined as recurrent abdominal pain at least three days per month in the previous three months, associated with two or more of the following: (3)
- Improvement with defecation
- Onset associated with change in stool frequency
- Onset associated with change in stool consistency
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IBS Medications Aim to Tame, Not to Treat
Not that long ago, IBS was dismissed as a psychosomatic disorder that was “all in your head.” Fortunately, it is now recognized as a legitimate gastrointestinal disorder, although it’s often poorly managed. Current treatments focus on alleviating the symptoms of IBS instead of actually fixing the underlying problems—but that’s a common theme in conventional treatment of modern chronic diseases. Medications prescribed for IBS include:
- Anticholinergic or antispasmodic drugs
- 5-HT3 antagonists
- Mast cell stabilizers (also used to treat asthma)
5 Causes of IBS You May Not Have Considered
In order to properly treat IBS, you’ll need to do some investigating to determine the cause. This article will summarize five causes of IBS that you may not be looking for—but should be.
1. Gut Dysbiosis
Ever-growing research links the gut microbiome to bone health, heart health, autoimmune disease, thyroid health, and more. It should be no surprise, then, that IBS is directly related to gut dysbiosis, a change in the composition of the gut bacteria. Up to 83 percent of IBS patients have abnormal fecal biomarkers, and up to 73 percent have intestinal dysbiosis. (6) Specifically, those with IBS tend to have decreased levels of “good” bacteria, such as Lactobacilli and Bifidobacteria, and increased levels of harmful strains such as E. coli and Clostridia. (7, 8) An increased ratio of Firmicutes-to-Bacteroidetes (two major classes of bacteria) is also common. (9)
Success in treating IBS with prebiotics and probiotics is further evidence that gut dysbiosis plays a role in IBS. A recent article reviewed 24 randomized placebo-controlled probiotic trials, the majority of which showed benefits of treatment. (10) Beneficial probiotic strains included B. animalis, L. rhamnosus GG, B. infantis, B. longum, and L. acidophilus. (11, 12, 13) Prebiotics, which act as food for the microbiota, can also help establish beneficial bacterial. (14, 15, 16)
Another strategy that can correct gut dysbiosis is a low-FODMAP diet, which eliminates foods containing certain carbohydrates that feed intestinal bacteria. (17, 18, 19) This method may help get the beneficial-to-harmful bacteria ratio back under control, but it works best as a short-term solution that is then followed by prebiotic/probiotic treatment. (20, 21, 22)
Small intestinal bacterial overgrowth (SIBO) is a special subset of gut dysbiosis in which the small intestines harbor an abnormal number of bacteria. Compared to the colon, the small intestine should have a bacterial concentration that is considerably lower. Bacterial overload in the small intestine can interfere with digestion and nutrient absorption.
SIBO may be present in up to 80 percent of IBS patients, although a recent meta-analysis reported a huge range of estimates (between 4 and 78 percent) across 50 studies. (23) Part of the reason for the discrepancies is non-uniform IBS diagnosis, and the other part may be variations in SIBO diagnosis. I prefer the methane breath test over jejunal aspirate and culture, the conventional testing approach.
Antibiotics that are used to treat SIBO, like rifaximin, can also be effective for treating IBS, further evidence that SIBO may be underlying some cases of IBS. (24, 25) Or, SIBO may follow IBS incidence, especially if a person with IBS begins taking PPIs (acid-blocking medications) for indigestion. One of the many dangers of PPIs is the development of SIBO. (26, 27)
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3. Gut Permeability
The GI tract is lined with a single layer of tightly packed epithelial cells designed to keep pathogens and other unwanted species out of the bloodstream. If the barriers between cells become permeable, undigested protein molecules and bacterial toxins can pass through and trigger immune reactions and inflammation.
Leaky gut and associated low-grade immune activation affect between 12 and 50 percent of people suffering from IBS. (28, 29, 30) Low levels of E-cadherin, a protein involved in regulating gut permeability, have been reported in IBS sufferers who experience diarrhea and/or constipation. (31)
Supplements that can help reestablish the intestinal barrier include:
- MSM and quercetin
- N-acetyl glucosamine
- DGL slippery elm
- Cat’s claw
4. Gut Infection
Gut infections are another lesser-known cause of IBS. Many studies have confirmed a link between a single episode of bacterial gastroenteritis and future development of IBS. (34, 35, 36) Parasites such as B. hominis, Giardia spp., E. histolytica, Dientamoeba fragilis, and Trichinella spp. have also been correlated with progression of IBS, although causation has not yet been confirmed. (37, 38, 39)
Modern lifestyle has compromised the gut’s ability to resist infections from pathogenic bacteria and parasites. (High levels of stress, for instance, combined with factors such as the Standard American Diet, can easily lower our immunity.) Gut permeability, gut dysbiosis, and high stomach pH from chronic PPI use create more opportunities for pathogens to overwhelm or bypass the gut’s immune defenses.
5. Non-Celiac Gluten Sensitivity and Other Food Intolerances
The medical field once mocked non-celiac gluten sensitivity (NCGS), but the condition is slowly gaining acceptance even in conventional medicine. (40) Many of the symptoms—gas, bloating, abdominal pain, and changes in stool patterns—are indistinguishable from IBS, so NCGS can be difficult to identify. Brain fog and fatigue following gluten consumption are also very common.
In IBS patients, I see a number of other food intolerances, such as:
A large review of over 73 studies “confirmed that food allergy and intolerance should be considered as an underlying pathology for IBS.” (41) But bear in mind that food intolerances themselves are often symptoms of deeper causes like SIBO, gut infections, and/or gut permeability.
The cheapest tool to determine food intolerances is an elimination diet, which I outline in depth in my book The Paleo Cure.
What’s Your Experience with IBS?
IBS can be an unpredictable and even debilitating condition. Finding the root cause is not always an easy or quick road, but neither is a lifetime of symptom-suppressing medications with additional side effects.
In my practice, I have seen patients who have suffered from this condition for 20 years recover after we identify and address the underlying causes of IBS outlined above and fix their diets.
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