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5 Causes of IBS Your Doctor May Not Be Looking For

What’s wrong with the conventional treatment for IBS?
The fundamental problem with the conventional approach to IBS is that it merely suppresses symptoms and doesn’t address the underlying causes. Look at the list of medications above. They are aimed primarily at slowing or increasing intestinal motility (to reduce diarrhea or constipation) and relieving pain.

#1: Small intestine bacterial overgrowth (SIBO)
SIBO is a condition characterized by abnormal overgrowth of bacteria in the small intestine. One study reported that up to 84 percent of IBS patients have SIBO and that patients with IBS were 26 times more likely to have SIBO than controls. (1)

Results from subsequent studies examining the association between SIBO and IBS were mixed. This is in part because there is currently no consistently accepted, gold-standard method of testing for SIBO, and the techniques varied from study to study.

However, there is other evidence to support the idea that SIBO plays a causal role in IBS for at least some patients. Antibiotics that are used to treat SIBO—such as rifaximin and neomycin—have been shown to be effective for treating IBS. For example, in one randomized controlled trial (RCT), treatment with rifaximin for 10 days resulted in symptom improvement that lasted for up to 10 weeks in IBS patients. (2) A recent meta-analysis of five studies found rifaximin to be effective for global IBS symptom improvement and more likely to reduce bloating than a placebo. (3)

#2: Disrupted gut microbiota (aka “dysbiosis”)
The human gut microbiota is a complex community of over 100 trillion microorganisms that influence physiology, metabolism, nutrition, and immune function. Disruption of the gut microbiota has been linked with GI conditions like inflammatory bowel disease as well as a wide range of extra-intestinal inflammatory conditions like diabetes and obesity.

Studies have shown that up to 83 percent of patients with IBS have abnormal fecal biomarkers, and 73 percent have intestinal dysbiosis (i.e., a disrupted gut microbiome). (4)

Numerous studies have also found that both prebiotics and probiotics, which modulate the gut microbiota, can be effective for treating IBS. (5) In addition, the low FODMAP diet, which restricts certain carbohydrates that feed intestinal bacteria, has been shown to benefit IBS patients. (6)

#3: Increased intestinal barrier permeability (aka “leaky gut”)
One of the primary roles of the gastrointestinal tract is to serve as a barrier system that prevents pathogens, undigested food particles, and other undesirable substances from entering the body.

IBS has been associated with increased permeability of the intestinal barrier in several studies, which may be modulated by a cytokine called interleukin-22 (IL-22) that is known to play a role in regulating gut permeability. (7, 8) Note that this is a structural change to the gut, which would suggest that IBS is not always a functional disorder.

#4: Gut infections
The human gut is naturally resistant to infection by pathogenic bacteria, thanks to acid produced in the stomach that is designed to kill potential invaders. However, many aspects of the modern diet lifestyle—such as chronic stress, poor diet, and use of acid-suppressing drugs—have compromised this defense system.

A number of gut infections have been linked to IBS. For example, food poisoning caused by Campylobacter bacteria leads to chronic, persistent IBS in as many as 10 percent of cases. (9) Intestinal parasites like Blastocystis hominis, Dientamoeba fragilis, and Giardia lamblia may be relatively common—yet often undiagnosed—causes of IBS, even in the developed world. (10)

#5: Non-Celiac Gluten Sensitivity and other food intolerances
Non-Celiac Gluten Sensitivity (NCGS) is a reaction to gluten that is not autoimmune (celiac disease) or allergic (wheat allergy). Despite claims to the contrary in the popular media, NCGS is a legitimate and potentially serious condition. In fact, I recently argued that it may be a greater public health challenge than celiac disease itself.

NCGS patients usually present with symptoms such as gas, bloating, abdominal pain, and changes in stool frequency and consistency that are indistinguishable from IBS. They also often present with extra-intestinal symptoms like “brain fog” and fatigue, which are common among IBS sufferers.

Intolerances to other foods like dairy products, eggs, peanuts, and seafood are also common among IBS sufferers. These may be true food allergies (IgE-mediated) or more mild intolerances (IgG- or IgA-mediated).

One recent, large review of 73 individual studies concluded that food allergy and intolerance—including reactions to wheat and gluten—should be considered as a potential underlying pathology for IBS. (11)

In my own clinical experience, I’ve found that both gluten/wheat sensitivity and other food intolerances are extremely common contributing factors to IBS. It’s worth pointing out that, in many cases, food intolerances are themselves caused by some of the other pathologies we’ve already discussed in this article. Put another way, both IBS and food intolerances are symptoms of deeper causes like SIBO and gut infections.

Read the rest here


Senior Member
2, 3, and 4.

I should say 3 of 5 that I know of. I haven´t had a SIBO test. I haven´t had a intestinal permeability test either, but that is the only thing that explains my fluctuating symptoms, and it is usually present when someone is infected with Yersinia.